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Tables of bond lengths determined by X-ray and neutron diffraction. Part 1. Bond lengths in organic compounds

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Abstract

The average lengths of bonds involving the elements H, B, C, N, O, F, Si, P, S, Cl, As, Se, Br, Te, and l in organic compounds are reported.

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... Therefore, the bond lengths and their variance can be effectively used to assess the π-electron delocalization and, in the case of cyclic systems, their aromaticity. [37], benzene (D6h symmetry, experimental data) [37], cyclopentadiene (B3LYP/6-311++G (d,p) results), and cyclopentadienyl anion (D5h, B3LYP/6-311++G (d,p) results). ...
... Therefore, the bond lengths and their variance can be effectively used to assess the π-electron delocalization and, in the case of cyclic systems, their aromaticity. [37], benzene (D6h symmetry, experimental data) [37], cyclopentadiene (B3LYP/6-311++G (d,p) results), and cyclopentadienyl anion (D5h, B3LYP/6-311++G (d,p) results). ...
... More details can be found in the review by Krygowski et al. [42]. [37], benzene (D 6h symmetry, experimental data) [37], cyclopentadiene (B3LYP/6-311++G (d,p) results), and cyclopentadienyl anion (D 5h, B3LYP/6-311++G (d,p) results). ...
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Aromaticity, a very important term in organic chemistry, has never been defined unambiguously. Various ways to describe it come from different phenomena that have been experimentally observed. The most important examples related to some theoretical concepts are presented here.
... Cell refinement and data reduction were carried out by Bruker SAINT. SHELXT [10,11] was used to solve the structure. The final refinement was carried out by full-matrix least-squares techniques with anisotropic thermal data for In this study, we examine the geometry of clonidine-tetraphenylborate as compared with data obtained by an X-ray diffraction experiment. ...
... As typical for tetraphenylborate, the tetraphenylborate anion is in a tetrahedral geometry around the B atom [C-B-C angles of 108.80 (19) • -110.13 (18) • ]. All the bond lengths and angles are in normal ranges [11]. The crystal structure is stabilized by C2-H2A···Cl2 hydrogen bonds along the c axis direction ( Figure 5, Table 3). ...
... (18)°]. All the bond lengths and angles are in normal ranges [11]. The crystal structure is stabilized by C2-H2A•••Cl2 hydrogen bonds along the c axis direction ( Figure 5, Table 3). ...
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The title compound tetraphenylborate salt of clonidine (Catapres®), 2-(2,6-dichlorophenylamino)-2-imidazoline tetraphenylborate (3), was prepared in 76 % yield by the reaction of 2-(2,6-dichlorophenylamino)-2-imidazoline hydrochloride (clonidine hydrochloride) (1) with sodium tetraphenylborate (2) in deionized water through anion exchange reaction at ambient temperature. The structure of the title borate salt was characterized by UV, thermal analysis, mass and NMR analyses. White crystals of (3) suitable for an X-ray structural analysis were obtained by slow growing from acetonitrile. The molecular structure of the titled compound (3) was crystallized in the acetonitrile, P21/c, a = 9.151 (3) Å, b = 12.522 (3) Å, c = 25.493 (6) Å, β = 105.161 (13)° V = 2819.5 (13) Å3, Z = 4. A DFT quantum chemistry calculation method was employed to investigate the interaction mechanism of clonidine with tetraphenylborate. The stable configurations of the complexes of clonidine with tetraphenylborate with electrostatic interactions were obtained. Finally, the interaction strength and type of the complexes were studied through the reduced density gradient (RDG) function. This study provides new theoretical insight into the interaction mechanism and a guide for screening and designing the optimal clonidine and tetraphenylborate reacting to form the complex.
... The bond lengths of the studied molecules 33 and 34 were usual [50] within the limits of errors. The lactone ring in molecules 33 and 34 had an envelope conformation with the C6 atom yielding by 0.327 (3) and 0.29 (1) Å from the plane of the rest of the cycle atoms. ...
... On the P-388 leukemia cell line, compounds 1, 2, 3, 11, and 13 showed higher activity compared to substance 4 (IC 50 17.94 ± 2.57 µM). ...
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The sesquiterpene γ-lactone estafiatin 1, the molecule of which has a structure of 3,4α-epoxy-1,5,7α,6β(H)-guai-10(14),11(13)-dien-6,12-olide, is characteristic of plants of the genera Achillea L. and Artemisia L. of the Asteraceae family. This article presents the results of chemical modification for three reaction centers of the estafiatin molecule 1: epoxy cycle, exomethylene group conjugated with γ-lactone carbonyl, and exomethylene group in position С10=С14; and at the same time 33 new derivatives were synthesized, the structures of which were established based on physicochemical constants, spectral data (IR-, PMR-, 13C-NMR), and X-ray diffraction analysis. The stereo- and regiospecificity, as well as the chemoselectivity of the reaction based on estafiatin molecule 1, are discussed. The reactivity of the substrate is significantly influenced by the stereochemistry of its molecule, the nature of the reagent, and the reaction medium. Based on the results of in silico screening, derivatives of estafiatin with high binding energies for both DNA-topoisomerase I and DNA-topoisomerase II were identified. The values of the inhibitory dose of IC50 for estafiatin 1 and its derivatives were determined on cell lines of eight types of tumors. In vivo experiments of the samples made it possible to establish that estafiatin 1 and its derivatives have pronounced antitumor activity against Pliss lymphosarcoma, Walker’s carcinosarcoma, sarcoma 45, sarcoma-180, alveolar liver cancer PC-1, leukemia P-388 and L-1210, and sarcoma-45 resistant to 5-fluorouracil.
... The C=N bond lengths (1.27-1.30 Å for 5-7) are typical for C=N double bonds [10,11,13,14,[25][26][27][28][29][30][31][32][33][34]. Other covalent bonds in 5-7 are unremarkable. ...
... In both compounds, the TFA is connected to the 1,2,4-selenodiazolium via two bond CPs The C=N bond lengths (1.27-1.30 Å for 5-7) are typical for C=N double bonds [10,11,13,14,[25][26][27][28][29][30][31][32][33][34]. Other covalent bonds in 5-7 are unremarkable. ...
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The synthesis and structural characterization of a series of supramolecular complexes of bicyclic cationic pyridine-fused 1,2,4-selenodiazoles with various anions is reported. The binding of trifluoroacetate, tetrachloroaurate, tetraphenylborate, perrhenate, and pertechnetate anions in the solid state is regarded. All the anions interact with selenodiazolium cations exclusively via a pair of “chelating” Se⋯O and H⋯O non-covalent interactions, which make them an attractive, novel, non-classical supramolecular recognition unit or a synthon. Trifluoroacetate salts were conveniently generated via novel oxidation reaction of 2,2′-dipyridyl diselenide with bis(trifluoroacetoxy)iodo)benzene in the presence of corresponding nitriles. Isolation and structural characterization of transient 2-pyridylselenyl trifluoroacetate was achieved. X-ray analysis has demonstrated that the latter forms dimers in the solid state featuring very short and strong Se⋯O and Se⋯N ChB contacts. 1,2,4-Selenodiazolium trifluoroacetates or halides show good solubility in water. In contrast, (AuCl4)−, (ReO4)−, or (TcO4)− derivatives immediately precipitate from aqueous solutions. Structural features of these supramolecular complexes in the solid state are discussed. The nature and energies of the non-covalent interactions in novel assembles were studied by the theoretical methods. To the best of our knowledge, this is the first study that regards perrhenate and pertechnetate as acceptors in ChB interactions. The results presented here will be useful for further developments in anion recognition and precipitation involving cationic 1,2,4-selenodiazoles
... For the generation of the HOMO-LUMO orbitals. The bond lengths of hydrogen atoms involved in interactions were normalized to standard neutron values ( [41]. Additionally, semi-empirical periodic density functional theory (DFT) calculations were performed using the CRYSTAL17 code [42][43][44] to evaluate the electronic properties of both compounds in the solid-state. ...
... Diffraction-quality single crystals for X-ray structure studies were obtained for compounds L1, 1, and 2 by different crystallization techniques for each compound (see the experimental section for more details). All compounds show normal bond angles and distances [41]. Additionally, Crystal data are summarized in Table 1, angles selected bond distances and angles, likewise intra-and intermolecular hydrogen bonds are provided in Tables S2 and S3. ...
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This article discloses the syntheses of two novel coordination polymers of Zn(II) and Cd(II) using a donor-functionalized 1,2,3-triazole-β-diketonato ligand, obtained by Claisen's condensation with ethyl 5-methyl-1-(pyridin-2-ylmethyl)-1H-1,2,3-triazole-4-carboxylate and 4-methoxyacetophenone. All compounds were characterized by spectroscopic solid-state techniques in solid-state, such as FT-IR, Single-crystal and powder X-Ray diffraction, luminescence, Thermal analyses (TGA/DSC), and, in the case of the precursor and donor ligand multinuclear NMR analyses. The syntheses of both coordination polymers were carried out under crystallization and bulk method, showing the same results in both methods according to the powder X-ray analyses. Thermal and luminescent properties allow us to conclude that these compounds are good candidates for UV – blue light emitters.
... Unfortunately, we were only able to obtain and solve the crystal structure of compounds The structural features of 21 b and 22 a were compared with diamondoid amines and amides whose crystal structures had been solved and reported, and with reference to tabulated bond lengths. [35] The CCDC and IUCr depositories contain a few entries for amides derived from adamantane. Entries were selected based on two criteria: a diamondoid moiety must be a direct substituent either on the N-side or on the acyl side, and the other substituents must either be a hydrogen or an alkyl chain (to avoid inductive or conjugative effects). ...
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Introduction of adamantane moieties on diamondoids such as adamantane, 2‐azaadamantane or diamantane by amide formation and reduction to the corresponding amine was performed in a straightforward and easy way by amidation under Schotten–Baumann conditions and reduction with BH3 ⋅ THF. The obtained amides and amines were studied in terms of structural properties towards the perspective of transformation into nanodiamonds. Crystal structure and dynamic NMR experiments of the most crowded amide obtained gave structural insights into the effect of bulkiness and steric strain on out‐of‐planarity of amide bonds (16.0°) and the kinetics and thermodynamics of amide bond rotation (ΔG≠298K=11.5–13.3 kcal ⋅ mol−1). Amines and amides derived from adamantane and diamondoids were synthesized and studied in terms of crystal structure, thermal properties and the dynamics of amide bond rotation. In particular, exalted out‐of‐planarity of amide bond (16.0°) or lowered energy barrier of amide bond rotation (11.5–13.3 kcal ⋅ mol−1) were observed for a derivative of 2‐azaadamantane.
... 26 Before the multipole refi nement, all hydrogen atoms determined from the high-resolution X-ray diff raction data were normalized to the ideal neutron diff raction distances. 27 The multipole expansion was truncated at the octapole level for all non hydrogen atoms and at the dipole level for hydrogen atoms. All bonded pairs of atoms satisfy the Hirshfeld rigid-bond criteria. ...
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A suspension of sparingly soluble zinc (1-hydroxyethylidene)diphosphonate ZnH2L•2H2O (H4L = MeC(OH)[P(O)(OH)2]2) is rapidly transformed into an aqueous solution when treated with ammonia or aliphatic amines (hexamethylenediamine, triethylamine, tert-butylamine, di-n-butylamine) containing no hydrophilic groups −OH and −(OCH2CH2)n−. The dissolution effect is due to the decomposition of the coordination polymer giving ammonium derivatives. Dehydrated dry powders of the corresponding ammonium compounds based on triethylamine, tert-butylamine, or di-n-butylamine rapidly dissolve in water to form transparent colorless solutions, whereas hexamethylenediamine and ammonia derivatives are poorly soluble. (1-Hydroxyethylidene)diphosphonic acid forms ammonium salts with hexamethylenediamine, triethylamine, and tert-butylamine. The molecular structures of these compounds are considered.
... The molecular structure of the synthesized title molecule develops in the triclinic space group P-1 by Z=2 and shows a centrosymmetric setting with normal bond distances and angles [28]. A summary of the crystal data, data collection, and structure refinement of title compound are documented in Table 1. ...
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Ethyl 4-(4-(dimethylamino)phenyl)-3,6-dimethyl-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylate (5) was synthesized according to our previously reported procedure in a 92% yield and crystallized by a slow evaporation technique. This report describes the in-depth structural analysis thereof. The structural characterization and purity of the title compound were determined by UVvis, FT-IR, 1H-NMR, and 13C-NMR spectroscopy, high-resolution mass spectrometry (HRMS), thermogravimetric analysis (TG/DTG), and its 3D-structure was confirmed by single-crystal X-ray diffraction. The synthesized title molecule crystallized in the triclinic space group P-1, Z=2. In the crystal packing, the cohesion among the different molecules is assured by one C–H···O hydrogen bond interaction. Hirshfeld surface analysis indicated that H···H bond interactions are the primary contributors to the intermolecular stabilization in the crystal.
... Subsequently, the hydrogen atoms of the CeH bonds of R were tightly associated with the oxygen atoms in the C]O group of F by forming hydrogen bonds. In the four-membered ring transition state, the CeC bond length was 1.56 Å, which is close to the normal CeC bond length [40], indicating that the CeC bond in the four-membered ring transition state was formed. Finally, the protons in this four-membered ring were transferred to the carbon atom of F forming o-hydroxymethyl resorcinol. ...
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Herein, we describe a simple and ultrafast method to synthesize carbon aerogel monoliths from resorcinol (R) and formaldehyde (F) using graphitic crystallite nanomaterials (GCNs). GCNs play the crucial roles in the simple and ultrafast synthesis of carbon aerogel monoliths. In the gelation step, GCNs significantly catalyze the addition reaction of RF resulting into the occurrence of RF gelation at room temperature within 30 min. In the drying step, GCNs not only provide the resulting aerogels with strong support to resist the high surface tension due to heat drying but also construct developed nanochannels with dimensions of hundreds of nanometers with the RF gel particles, thereby permitting water to quickly and isotropically vaporize during heat drying hydrogel. Consequently, carbon aerogel monoliths without any fractures can be synthesized within one day by direct heat drying under ambient pressure instead of the conventional 1–2 weeks. These carbon aerogels have highly developed mesoporosity, high compressive strength of 24–82 MPa and electrical conductivity of 9–25 S/cm, depending on the dosages of GCNs, catalyst and water, as well as their subsequent treatment.
... 53 In the case of the quantum mechanics−molecular mechanics (QM/MM) method, the crystal environment was modeled by cutting out a shell with a radius of 15 Å around the central molecule from the examined experimental crystal structure, 54 the C−H distances of which were set to the neutron-normalized values. 55,56 Density functional theory (DFT) at the DFT(B3LYP)/6-311++G** level of theory was applied for the optimization of the central molecule, 57 63 using Hirshfeld atomic charges 64 initially derived at the same level of theory, including both the functional and the basis set. Dimer interaction energies, isolated-molecule geometry optimizations, and normal-mode frequencies were also calculated at the DFT(B3LYP)/ 6-311++G** level of theory. ...
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Two photoswitchable nickel(II) nitro coordination compounds and their copper(II) analogues are reported. In all these systems, the metal center is chelated by (N,N,O)-donor ligands containing either 2-picolylamine or 8-aminoquinoline fragments. The studied compounds were thoroughly investigated using crystallographic and spectroscopic techniques supplemented by computational analysis. They are easy to synthesize and stable, and all compounds undergo the nitro group isomerization reaction. Nevertheless, there are significant differences between the copper and nickel systems regarding their structural and switchable properties. According to the solid-state IR spectroscopy results, 400-660 nm light irradiation of the ground-state (η2-O,O')-κ-nitrito copper(II) complexes at 10 K induces a rather moderate conversion to a metastable linkage isomer, which is visible only up to approximately 60-80 K. In turn, upon visible light irradiation (ca. 530 nm excitation wavelength), the ground-state nitro isomers of the examined nickel(II) complexes transform into the endo-nitrito forms. It was possible to achieve about 35% conversion for both nickel(II) systems and to determine the resulting crystal structures at 160 K in the case of single crystals after 30-45 min of exposure to LED light (crystals decayed with longer irradiation), and roughly 95% conversion was achieved for thin-film samples as indicated by the IR spectroscopy results. Traces of the endo-nitrito linkage isomers remained up to 200-220 K, and the isomerization reaction was proven to be fully reversible.
... The six Ni-O bond lengths are 1.974 (2) and 2.003 (2) Å for DHA molecules and 2.108 (2) Å ( Table 2). These values are in good agreement with related reported complexes [37,38]. The selected cis angles of the nickel environments deviate from their ideal values only for 90° angles and found to be in the ranges 87.65 (8)°-92.35 ...
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This work explores the study of a synthesized nickel complex as a possible inhibitor against the main protease (Mpro) of the recent emerging coronavirus disease (COVID-19). Overall, the template reaction of 3-acetyl-2-hydroxy-6-methyl-4H-pyran-4-one with nickel(II) chloride hexahydrate in N,N-dimethylformamide (DMF) medium leads to the formation of neutral nickel complex. This resulting complex is formulated as [Ni(DHA)2(DMF)2] on the basis of FT-IR, UV-Vis., single-crystal X-ray diffraction analysis, magnetic susceptibility and CV measurements as well as DFT quantum chemical calculations. Its single crystal suggests was found to be surrounded by the both pairs of molecules of DHA and DMF through six oxygen atoms with octahedral coordination sphere. The obtained magnetic susceptibilities are positive and agree with its paramagnetic state. In addition to the experimental investigations, optimized geometry, spectroscopic and electronic properties were also performed using DFT calculation with B3LYP/6-31G(d,p) level of theory. The nonlinear optical (NLO) properties of this complex are again examined. Some suitable quantum descriptors (EHOMO, ELUMO, Energy gap, Global hardness), Milliken atomic charge, Electrophilic potion and Molecular Electrostatic Potential) have been elegantly described. Molecular docking results demonstrated that the docked nickel complex displayed remarkable binding energy with Mpro. Besides, important molecular properties and ADME pharmacokinetic profiles of possible Mpro inhibitors were assessed by in silico prediction.
... The N(1) atom has an almost planar configuration, the sum of In the ethoxy group the C(4) -C(5) bond is shortened to 1.495(4) Å compared to the average length of C(sp 3 ) -C(sp 3 ) ordinary bond (1.540 Å [17] ). The similar shortening of the C-C bond in Nethoxy substituent takes place in 3-ethoxy-5-phenylimidazolidine-2,4-dione [3] . ...
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Phenylglyoxal and thien-2-ylglyoxal react with N-alkoxy-N’-phenylureas in acetic acid at room temperature with a selective formation of the 3-alkoxy-1,5-bis(phenyl)imidazolidine-2,4-diones and the 3-alkoxy-1-phenyl-5-(thien-2-yl)imidazolidine-2,4-diones, respectively. In the same conditions phenylglyoxal interacts with N-ethoxy-N’-4-methylphenylurea, N-alkoxy-N’-4-bromophenylureas and N-alkoxy-N’-4-nitrophenylureas yielding the 3-alkoxy-1-aryl-cis-4,5-dihydroxy-5-phenylimidazolidin-2-ones. The 3-alkoxy-4,5-dihydroxy-1-(4-methylphenyl)-5-phenylimidazolidin-2-ones and the 3-alkoxy-1-(4-bromophenyl)-4,5-dihydroxy-5-phenylimidazolidin-2-ones easily form the proper 3-alkoxy-1,5-bis(aryl)imidazolidine-2,4-diones influenced by the strong acids. The XRD-analysis of the 3-alkoxy-1-aryl-5-phenylimidazolidine-2,4-diones, the 3-alkoxy-1-phenyl-5-(thien-2-yl)imidazolidine-2,4-diones and 3-benzyloxy-cis-4,5-dihydroxy-1-(4-nitrophenyl)-5-phenylimidazolidin-2-one has demonstrated their distinctive structural features. In the asymmetric part of the unit cell 3-ethoxy-1,5-bis(phenyl)imidazolidine-2,4-dione and 3-benzyloxy-1-(4-bromophenyl)-5-phenylimidazolidine-2,4-dione exist as the pair of independent molecules which differ by some structural parameters. In 3-benzyloxy-4,5-dihydroxy-1-(4-nitrophenyl)-5-phenylimidazolidin-2-one the hydroxyl groups are cis-oriented towards each other. The elongation of the (HO)C-C(OH) endocyclic bond takes place.
... Å and 1.628-1.691 Å, respectively [54]. In the N 3 P 3 phosphazene ring of 2a and 2b, the average endocyclic P-N bond lengths are 1.593(3) and 1.591(3) Å, respectively. ...
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Substitution reaction of hexachlorocyclotriphosphazatriene (trimer; N3P3Cl6; HCCP) with N,N'-bis(4-fluorobenzyl)ethane-1,2-diamine (1) gave the starting compound tetrachlorobis(4-fluorobenzyl)monospiro(N/N)cyclotriphosphazene (2). Tetraaminobis(4-fluorobenzyl)spiro(N/N) cyclotriphosphazenes (2a-2c) were synthesized from the substitution reactions of spiro (2) with excess piperidine, ethylpiperazine and phenylpiperazine, respectively, in boiling THF. Elemental analysis, ESI-MS, FTIR, ¹H, ¹³C and ³¹P NMR data verified the structures of new compounds; and the solid-state crystal structures of 2a and 2b were elucidated using the X-ray crystallography method. Hirshfeld surface (HS) analyses were performed to figure out the intermolecular interactions in these crystals as well. Moreover, the minimum inhibitory, bactericidal and fungicidal concentrations (MIC, MBC and MFC) were determined using the microdilution method, which was used to detect the compounds that have the antimicrobial effects on microorganisms exhibited the effect at which concentration. It was concluded that MIC, MBC and MFC values ranged from 312.5 and >2500 µM. Furthermore, DNA cleavage and unwinding properties of 2a, 2b and 2c with pBR322 plasmid DNA were examined by agarose gel electrophoresis. Also, compound-DNA incubation and BamHI and HindIII restriction enzyme digestions were realized to provide more insight into changes in DNA conformation. Finally, the antioxidant activity was determined that 2c had the highest antioxidant capacity with a 38.38% radical scavenging activity value.
... 44,46,47 The average lengths of the CO bonds (1.235 Å) and endocyclic CC bonds (1.347 Å) in diphenoquinone 2 are closely similar to those observed in benzoquinone (1.222 and 1.322 Å, respectively), 75,76 as well as in diphenoquinone 17. The central interannular CC bonds in unsubstituted diphenoquinone 2 and tetrasubstituted analogue 17 are also similar in length (1.385 and 1.395 Å, respectively) and are significantly longer than normal CC bonds (1.34 Å). 77 In the structure of diphenoquinone 2, molecules aligned along the ac-diagonal are linked into chains by paired C−H···O interactions with O···H distances of 2.543 Å (Figure 1a). These distances are significantly shorter than the sum of the van der Waals radii of hydrogen and oxygen (2.72 Å). ...
Article
Benzoquinones can undergo reversible reductions and are attractive candidates for use as active materials in green carbon-based batteries. Related compounds of potential utility include 4,4'-diphenoquinones, which have extended quinonoid structures with two carbonyl groups in different rings. Diphenoquinones are a poorly explored class of compounds, but a wide variety can be synthesized, isolated, crystallized, and fully characterized. Experimental and computational approaches have established that typical 4,4'-diphenoquinones have nearly planar cores in which two cyclohexadienone rings are joined by an unusually long interannular C═C bond. Derivatives unsubstituted at the 3,3',5,5'-positions react readily by hydration, dimerization, and other processes. Association of diphenoquinones in the solid state normally produces chains or sheets held together by multiple C-H···O interactions, giving structures that differ markedly from those of the corresponding 4,4'-dihydroxybiphenyls. Electrochemical studies in solution and in the solid state show that diphenoquinones are reduced rapidly and reversibly at potentials higher than those of analogous benzoquinones. Together, these results help bring diphenoquinones into the mainstream of modern chemistry and provide a foundation for developing redox-active derivatives for use in carbon-based electrochemical devices.
... Also, the C=O distances of the carboxylate groups of PRO1 and PRO2 range from 1.235 to 1.256 Å. These values are consistent with resonant structures [56]. ...
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In this work, we present the formation of a new multi-component molecular complex by targeting the boronic acid moiety (-B(OH)2) of 4-acetylphenylboronic acid with the carboxylate group (-COO⁻) of l-proline using two different techniques: mechanochemistry and solvent evaporation. The experiments produced efficiently a new cocrystal named L-PRO4APBA. It was characterised to study its structural properties by X-ray powder diffraction (XRPD), infrared spectroscopy (FTIR), single-crystal X-ray diffraction (SCXRD), and quantum chemical methods based on QTAIM. Also, its thermal behaviour was analysed using a simultaneous DSC/TGA experiment. The results showed that L-PRO4APBA comprises discrete molecular units held together mainly by O–H⋯O and N–H⋯O hydrogen bonds. However, C–H⋯O, C–H∙··π, and other non-conventional interactions gave further stabilisation. Moreover, SCXRD showed that the asymmetric unit contains five independent molecules: two of l-proline (PRO1 and PRO2), two of 4-acetylphenylboronic acid (4APBA1 and 4APBA2) and one of water. PRO1 and PRO2 adopted different conformations with their carboxylate groups in equatorial and axial positions, respectively. This feature produced two independent helical chains running along the 21 screw axis in which 4APBA1 and 4APBA2 bound through the expected -B(OH)2···⁻OOC- heterosynthon. Surprisingly, the presence of water molecules in the lattice did not disrupt the formation of this motif. However, water molecules played an essential role for the stabilisation of the 3D structure. These findings would set up the structural basis to continue exploring the formation of new cocrystals by combining l-proline with boronic acids.
... Whilst the crystallographic data for compound (II) is listed in Table 1 and the selected bond lengths and angles are tabulated in Table 2. All the bond distances and angles are in good agreement with those values reported earlier for other analogous compounds [20]. ...
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Three linear mixed-valence trinuclear cobalt(III)-cobalt(II)-cobalt(III) complexes, [CoII{(μ-L¹)(μ-OOCCH3)CoIII(OOCCH3)}2]⋅4H2O (1), [CoII{(μ-L²)(μ-OOCCH3)CoIII(OOCCH3)}2]⋅4H2O (2) and [CoII{(μ-L¹)(μ-OOCPh)CoIII(OOCPh)}2] (3), have been synthesized using two tetradentate N2O2 donor 'reduced Schiff base' ligands, H2L¹ (2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(4-chlorophenol) and H2L² (2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(4-bromophenol), and acetate or bezoate as anionic co-ligands The complexes have been characterized by spectroscopic measurements and their solid state structure have been determined by single crystal X-ray diffraction analysis. DFT calculations have been performed to study the mixed valence nature of the complexes. Moreover, the structure directing role of several noncovalent interactions in the solid state of the complexes has been investigated. The interactions have been characterized by a combination of two computational tools based on the topological analysis of the electron density, which are the quantum theory of atoms-in-molecules (QTAIM) and the noncovalent interaction plot, since they are useful to reveal noncovalent interactions in the solid state.
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The O,N,S-tris-chelating ligand, H2NSCN-N=C(H)ArO⁻ constitutes an attractive scaffold in coordination chemistry and we have expanded this scaffold by installing an alkyl group of different steric hindrance. Thus, the ligand scaffolds containing O,N,S (Lⁿ) differ with respect to the chemical link between the coordinating O atoms, which is either a phenol or a naphthol moiety and carrying a cyclohexyl or a adamantyl groups (L¹, phenol and cyclohexyl; L², naphthol and cyclohexyl; L³, phenol and adamantyl; L⁴, naphthol and adamantyl). Six novel diorganotin(IV)-Lⁿ compounds 1-6 were synthesized and structurally characterized. The solid-state structures were deduced from single crystal X-ray diffraction data, and revealed the Sn(IV) cations adopting square pyramid (in 2, 3 and 4) or trigonal bipyramid (in 1, 5 and 6) geometries with coordination spheres comprising κ-N,O,S (κ-N,S in 1) ligand chelators and two methyl or phenyl groups (plus a hydrosulfide in 1) co-ligands. Solution state characterizations were achieved by detailed ¹H, ¹³C, ¹⁵N and ¹¹⁹Sn NMR analysis including selected 2D experiments. In vitro cytotoxic activities of the compounds were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay against human histiocytic lymphoma U-937 cells. The IC50 values revealed better activities of diphenyltin(IV) compounds 4-6 as compared to the respective pro-ligands and doxorubicin. More importantly, compounds 4-6 demonstrated maximum inhibition in U-937 cells (IC50 = 0.47-0.99 μM), with negligible effect on human peripheral blood mononuclear cells (PBMC). Compounds 4-6 effectively inhibited cell viability event, which was confirmed by detecting cytotoxicity, Live & Dead and Lactate dehydrogenase (LDH) release assays.
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A novel co-crystal of 3-aminobenzoic acid with 4-acetyl pyridine (ABA:AP) has been synthesized and its structure determined by single crystal X-ray diffraction (SCXRD) methods. It crystallizes in the monoclinic crystal system with space group P21/n and unit cell parameters a = 7.573(11) Å, b = 10.718(11) Å, c = 15.77(2) Å, β = 98.10(10)°, Z = 4. The co-crystal is stabilized by R22(8) ring motif, hydrogen bonding and π-π interactions. Density functional theory (DFT) and Hartree Fock (HF) methods with basis set of B3LYP/6-311+G(d,p) have been employed to obtain the optimized structural geometry, Mulliken charges, molecular electrostatic potential (MSP) and frontier molecular orbitals. The contribution of distinct interactions within the molecule and the strength of molecular packing in the co-crystal have been investigated by Hirshfeld surface (HS) analysis.
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The title compound, C 10 H 13 BrN 2 O 3 S, 1 , contains a sulfonyl urea moiety, which possesses potential therapeutic functions ( e.g. , anti-diabetic and herbicidal). The geometry of 1 is similar to its closely related analogues, chlorpropamide and tolbutamide. This compound crystallizes in the monoclinic space group C 2/ c , having one molecule in its asymmetric unit. The crystal structure of 1 , recorded at 296 K, shows intermolecular N—H...O and C—H...O-type infinite hydrogen-bonded chains involving the sulfonyl urea moiety. Hirshfeld surface analysis and the two-dimensional fingerprint plots confirmed hydrogen bonding as the dominant feature in the crystal packing.
Article
Usually, chalcones are not luminescent, although their derivatives with push-pull patterns of substitution may present fair quantum yields. Intramolecular hydrogen bonding between a hydrogen donor (–OH or –NH) and the chalcone carbonyl promotes Excited State Intramolecular Proton Transfer (ESIPT). If the dye is fluorescent, the emission can derive from one of the excited tautomers, or from both and in this case a dual emission is observed. Here, 2′-aminochalcones with a strong push-pull character, incorporating electron-donating groups on one side, and electron-withdrawing groups on the amine, present dual emission ascribed to ESIPT between the keto-enamine and the enol-imine tautomers. The hydrogen bonds strength was studied by NMR and DFT calculations. A correlation between the tautomerization energy gap and the hydrogen bond strength was observed, depending on the electron donating or electron withdrawing group on the amine. The electron withdrawing groups bonded to the proton donor have little influence on the quantum yield and emission wavelength. In contrast, the electron donating groups connected to the proton acceptor have a significant effect on the quantum yield and induce an absorption and emission red shift.
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A family of Pt(II) complexes bearing monoanionic C^N^N ligands as luminophoric units as well as a set of monodentate ligands derived from allenylidene and carbene species were synthesized and characterized in terms of structure and photophysical properties. In addition, we present the extraordinary molecular structure of a phosphorescent complex carrying an allenylidene ligand. Depending on the co-ligand, an effect can be observed in the photoluminescence lifetimes and quantum yields as well as in the radiative and radiation less deactivation rate constants. Their correlation with the substitution pattern was analyzed by comparing the photoluminescence in fluid solution at room temperature and in frozen glassy matrices at 77 K. Moreover, in order to gain a deeper understanding of the electronic states responsible for the optical properties, density functional theory calculations were performed. Finally, the cytotoxicity of the complexes was evaluated in vitro, showing that the cationic complexes exhibit strong effects at low micromolar concentrations. The calculated half-maximum effective concentrations (EC50 values) were 4 times lower in comparison to the established antitumor agent oxaliplatin. In contrast, the neutral species are less toxic, rendering them as potential bioimaging agents.
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It is shown that replacing the experimental electron density with the theoretical one on the terbium atom describes the experimental topology in the coordination sphere with high accuracy. Such a replacement is fundamentally important in the case of high residual electron density on a heavy metal atom.
Article
A novel Schiff base 2, 4- Bis (2-hydroxy naphthaldehyde) diiminotholuene (L), was prepared and characterized by the analysis techniques: FT-IR, UV-Vis, ¹H and ¹³C NMR. X-Ray Diffraction (XRD), showing that the L was crystallized in phenol-imine form. The corrosion inhibition of carbon steel in 1 M hydrochloric acid solutions of ligand L was studied using chemical (weight loss) and electrochemical (potentiodynamic and electrochemical impedance spectroscopy (EIS)) measurements, these measurements show that the inhibition efficiency obtained by this compound increased by increasing the concentration of L. The polarization studies show that this L acts as mixed type inhibitor. This inhibitor functions through adsorption following Langmuir isotherm. The UV-Vis absorption spectroscopy was used to investigate the forming of complex between inhibitor L and Fe. The scanning electron microscopy (SEM) studies the metal surfaces confirming the formation of the adsorbed layer of inhibitor, which slows down the corrosion process in the corrosive solution. The Density functional theory (DFT) and Simulations of the Molecular Dynamics (SMD) were used to determine the relationship between quantum chemical parameters and their inhibition efficiencies, and the correlation between theoretical and experimental results was discussed.
Article
4-Tertiarybutylcyclohexanonethiosemicarbazone (4-TBCHTSC), crystallises in monoclinic crystal system with space group P21/c. The unit cell parameters were a=14.910(2) Å, b=8.3353(12) Å, c=10.5506(18)Å and α=90°, β=95.272(7)°, γ=90°, V=1305.6(4)ų. Z = 4. From the obtained crystallographic data, the Cyclohexylidene ring structure adopts chair conformation and also the lengths of bonds in thiosemicarbazone moiety suggest extensive electron delocalization in it. Three intermolecular hydrogen bonds involving each sulphur atom results in a sheet like arrangement and the packing structure involves the arrangement of these sheets as layers without any interactions between them except van der Waals forces of attraction. Theoretical optimization of the crystal was done by computational methods using Gaussian softwares. FMO, MEP, NBO were detected and also molecular docking of the compound was done to detect its binding affinity towards anti apoptotic protein BCL2 and pro apoptotic protein BAX. Experimental in-vitro anti-proliferative activity study by MTT assay against SK MEL-28 cell lines suggest high cytotoxic activity, indicating possible use as a potential antitumor agent.
Article
A novel Cu(II) based one-dimensional (1D) zig-zag coordination polymer (CP) formulated as [Cu(muco)(4,4′-Me2bpy)(H2O)]·2H2O (1; H2muco = trans, trans-1,3-butadiene-1,4-dicarboxylic acid or trans, trans-muconic acid and 4,4′-Me2bpy = 4,4′-dimethyl-2,2′-bipyridine) was synthesized in a self-assembly reaction using slow evaporation technique. Single crystal X-ray analysis reveals that the compound 1 crystallizes in the triclinic system, space group Pī with a = 9.7436(12) Å, b = 11.1836(14) Å, c = 11.5063(14) Å; α = 61.520(1)°, β = 85.019(1)°, γ = 66.864(1)° and V = 1005.6(2) ų. Its structure is composed of Cu(II) centres with a distorted square pyramidal configuration interconnected by muco ligand in an array to generate zig-zag chain. A three- dimensional (3D) supramolecular network is formed among 1D chains of 1 via hydrogen bonding and π··π interactions. Interestingly, the connectivity of lattice water molecules shows a water dimer cluster, which further undergoes hydrogen bonding along with coordinated water molecules and oxygen atoms of muco ligands to generate an octameric cluster with chair-like hexameric unit. The excellent coordinating characteristics of muco and bipyridine ligands owing to non-covalent interactions to stabilize compound 1 have been investigated by means of Hirshfeld analysis. The density functional theory (DFT) study is performed to calculate the HOMO-LUMO gap which enlightens the possible future application of 1 as a semiconducting device. The theoretical findings are also validated experimentally by band gap calculation utilising Tauc’s plot exploring the UV data.
Article
C 8 H 11 N 8 O 6 , monoclinic, P 2 1 / n (no. 14), a = 5.6348(8) Å, b = 19.485(3) Å, c = 11.5316(17) Å, β = 101.013(2)°, V = 1242.8(3) Å ³ , Z = 4, R gt ( F ) = 0.0396, w R ref ( F ² ) = 0.1039, T = 296(2) K.
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Pure and barium ion (Ba²⁺)-doped ammonium di hydrogen ortho phosphate (ADP) crystals were grown from aqueous solution using a slow evaporation process. The presence of Ba²⁺ ions in the lattice was confirmed by X-ray diffraction (XRD) pattern of the grown crystals, which revealed improved transparency for the compound. Green emission was observed in photoluminescence studies of the grown crystals. The results of Fourier-transform infrared (FTIR) spectroscopy, ultraviolet–visible (UV–visible) spectrum analysis, energy-dispersive X-ray analysis (EDAX) and dielectric studies on the grown crystals were reviewed in detail. A regular slow cooling evaporation method was used to grow the crystals of pure and Ba²⁺-doped ADP from aqueous solution.
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The synthesis of iron complexes bearing amidomethylpyridine ligands, one homoleptic [2‐[(2,6‐iPr 2 ‐C 6 H 3 )NC(Me)]C 5 H 4 N] 2 Fe ( 1 ) complex and two heteroleptic silylamide iron complexes [2‐[(2,6‐iPr 2 ‐C 6 H 3 )NC(Me)]‐6‐R‐C 5 H 4 N]Fe(N(SiMe 3 ) 2 )C 5 H 5 N (R = H, 2 Py and R = Me, 3 Py ), are described together with their application as catalysts for the Ring‐Opening Polymerization (ROP) of rac ‐lactide ( rac ‐LA). The determination of the crystal structure of the three iron complexes is reported as well as their behavior in solution by means of 1 H NMR studies. All of these complexes have shown to be active for the polymerization of rac ‐LA at 50 °C in toluene, producing, among others, high molecular weight polylactides (PLA) according to SEC analysis, along with a portion of low molecular weight cyclic polymer ( c PLA) on the basis of MALDI spectra.
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In this paper, a lophine-based phenol compound has been prepared and identified as an efficient chromophore for the determination of hydrogen peroxide (H2O2) with enzymatic method. A dry chemistry analytic agent was also prepared involving this compound, showing good accuracy in the determination of uric acid. However, a commonly used solvent dichloromethane (DCM) could react with this imidazole derivative when the reaction mixture was irradiated under UV (365 nm). We explored the possible mechanism and identified several by-products caused by the acidity and ultraviolet oxidation of DCM. Caution should be taken in the synthesis and application of such imidazole-based dyes in DCM, especially when phenol group was introduced to the imidazole moiety.
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Trans-dichloro bis[N,N-dibutyl-N'-(4-chloro-benzoyl)thioureato-κS]palladium(II) complex (Trans-[PdIICl2(HBTU-κS)2]) is formed by reaction between PdCl2 and N,N-dibutyl-N'-(4-chlorobenzoyl)thiourea (BTU) in acetonitrile. Cis-bis[N,N-dibutyl-N'-(4-chlorobenzoyl) thioureato-κ²O,S]palladium(II) (cis-[PdII(BTU-κ²S,O)2]) is obtained by recrystallization of trans-[PdIICl2(HBTU-κS)2] in ethanol:dichloromethane solvent mixture. The prepared ligand coordinates with Pd(II) ion in monodentate coordination mode for trans-[PdIICl2(HBTU-κS)2] and in bidentate coordination mode for cis-[PdII(BTU-κ²S,O)2]. Both Pd(II) complexes have been characterized by elemental analysis, FT-IR, ¹H NMR, ¹³C NMR, and UV-Vis techniques. The detail structural formulations of trans-[PdIICl2(HBTU-κS)2] and cis-[PdII(BTU-κ²S,O)2] have been defined by X-ray single-crystal diffraction. The palladium complexes were also applied as an efficient catalyst for the Suzuki-Miyaura cross-coupling reaction of aryl halides with aryl boronic acids at 110°C using a very low substrate/catalyst ratio.
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The successful application of fragment‐based drug discovery strategy for the efficient synthesis of phenoxy‐ or phenylamino‐2‐phenyl‐benzofuran, ‐benzoxazole and ‐benzothiazole quinones is described. Interestingly, in the final step of the synthesis of the target compounds, unusual results were observed on the regiochemistry of the reaction of bromoquinones with phenol and aniline. A theoretical study was carried out for better understanding the factors that control the regiochemistry of these reactions. The substituted heterocyclic quinones were evaluated in vitro to determine their cytotoxicity by the MTT method in three pancreatic cancer cell lines (MIA‐PaCa‐2, BxPC‐3, and AsPC‐1). Phenoxy benzothiazole quinone 26a showed potent cytotoxic activity against BxPC‐3 cell lines, while phenylamino benzoxazole quinone 20 was the most potent on MIA‐PaCa‐2 cells. Finally, electrochemical properties of these quinones were determined to correlate with a potential mechanism of action. All these results, indicate that the phenoxy quinone fragment led to compounds with increased activity against pancreatic cancer cells.
Thesis
This thesis discusses the design and preparation of chiral P-alkene ligands, their complexation chemistry with some first and second row transition metals, and finally their catalytic application in several asymmetric organic transformations. More specifically, it consists of six chapters, of which chapters one to three refer to the use of new dibenzazepine-based chiral phosphoramidite P-alkene ligand complexes in Pd(II) catalyzed allylic amination, Ni(0) catalyzed cyanosilylation and Ni(II) catalyzed hydrovinylation reactions, respectively. On the other hand, chapters four to six describe the unprecedented use of the planar chirality that arises from the phenyl substitution in the alkene moiety of the dibenzazepine fragment to form new chiral phosphoramidites and P stereogenic P-alkene ligand systems that, upon complex formation with Ru(II), Rh(I), Ni(0) Pd(0) and Pd(II) precursors, catalytic tests were performed for C-C, C-H and C-N bond forming reactions.
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The Schiff base (E)-N-((4-((2-hydroxy-5-methoxybenzylidene)amino)phenyl)sulfonyl) acetamide (ScB-SAM) has been synthesized by their condensation at room temperature in ethanol. X-ray crystallographic analysis revealed that the keto-enol tautomerism of its solid state exists as a complex equilibria system that is stabilized intramolecular hydrogen bond. The enol, keto and mixed enol-zwitterionic forms were observed in the crystal structure. The crystallographic results were supported by ATR, and UV-Vis. Physical properties were determined in different polar and nonpolar solvents and solid state. All above experimental results were then compared with DFT calculations. Additionally, the stabilities of the trivalent: iridium, rhodium and ruthenium ions complexes with ScB-SAM have also been investigated by spectrophotometric titration methods in water. The data showed that the examined coordination compounds were stable in solution based on the values of their stability constants found.
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A series of new silyl-substituted benzimidazolium salts were synthesized in good yield by the reaction of 1-(dimethylvinylsilyl)methylbenzimidazole and various alkyl halides. These salts were characterized by spectroscopic techniques. Also, crystal structure of 2c has been determined by the single-crystal X-ray diffraction method. Newly synthesized compounds were tested for antibacterial and antifungal activities and the minimum inhibitory concentrations were determined. The results indicates that some of compounds exert effective antibacterial activity against four Gram (-) bacterial and four Gram (+) bacterial strains and two yeast strains.
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New tetrahydropyrazino[2,3-c]quinolin-5(6H)-ones were prepared from 3-chloroquinoline-2,4(1H,3H)-diones and ethylene diamine. In their reaction with HNCO, an unprecedented molecular rearrangement produced new types of hydantoin derivatives. All prepared compounds were characterized on the basis of their 1H, 13C, and 15N NMR and ESI mass spectra and some were authenticated by X-ray analysis of single crystalline material. A proposed mechanism for rearrangement is discussed in this essay. The CDK and ABL inhibition activity as well as in vitro cytotoxicity of the prepared compounds was also tested.
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The (Z)-4-aryliden-2-(2-acetoxyphenyl)-5(4H)oxazolones 1a-1c react with H2SO4 to give the corresponding (Z)-4-aryliden-2-(2-hydroxyphenyl)-5(4H)oxazolones 2a-2c.The molecular structures of 1c and 2a have been determined by X-ray diffraction methods, and show planar skeletons. Oxazolones 2a-2c are potential C,N,O-tridentate ligands towards transition metals, and their molecular design obeys to the search of a rigid environment around the metal. The reaction of Pd(OAc)2 with oxazolones 2a-2c (1:1 molar ratio) in CF3CO2H or NCMe as solvents results in the synthesis of diverse complexes (3-7). As a function of the reaction conditions, two different bonding modes have been characterized: N,O-chelate in the dinuclear complexes [Pd(κ²-N,O-2b,c)(μ -O2CCF3)]2 (3b,c), as a result of the N-coordination and deprotonation of the hydroxy group; and C,N,O-tridentate in mononuclear complexes [Pd(κ ³-C,N,O-2a,b)(L)] (L = CF3CO2H 4a,b; dmso-d6 5a,b; NCMe 6b; pyridine 7b), obtained after N-bonding, OH deprotonation and C-H bond activation. All complexes have been fully characterized by HRMS and NMR methods, showing the high stability of the C,N,O-tridentate bonding mode.
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This work is devoted to the study of the weak interactions present in the crystal packing of a new synthesized carbohidrazide derivate. The crystal structure was determined by X-Ray single crystal diffraction. The crystallographic asymmetric unit was optimized using DFT and compared with the experimental data. The nucleophilic and electrophilic regions were carried out with the molecular electrostatic potential. Hirsfeld analysis and noncovalent interaction approach were computed to quantificate the weak interactions responsible for the arrangement and stabilization of the molecular crystal packing. These approaches provides a rich representation for the analysis of noncovalent interactions in real space, in terms of the electron density and its derivates, of Van der Waals interactions, Hydrogen Bonds and the inter and intramolecular steric repulsions. The potential biological activity as an anticancer drug was tested with the molecular docking study in the catalytic center of a human Topoisomerase.
Article
Through the hydrothermal reaction of cobalt(II) perchlorate hexahydrate with 5-bromo-6-methyl-pyridine-2-carboxylic acid (5-Br-6-Me-Hpyc) and 1,4-bis(4-pyridyl)benzene (1,4-bpb) coligands, a cobalt(II) complex [Co(5-Br-6-Me-pyc)2(H2O)]·2H2O (1) and an organic-inorganic adduct [H2(1,4-bpb)]·2ClO4 (2) have been co-synthesized in the same medium. Structural analyses indicated that the cobalt(II) ion in 1 is penta-coordinated by one water and two bidentate chelate 5-Br-6-Me-pyc anionic ligands to obtain an asymmetric mononuclear species. While in 2, the two pyridyl groups of 1,4-bpb acquire two protons forming a bivalent cation pyridinium, which combine two perchlorate anions via N–H⋯O hydrogen bonds to fabricate an interesting anion-cation supramolecular adduct 2. The magnetism for 1, fluorescence for 2 as well as the hirshfeld surface structures for them have been carefully described and discussed.
Article
C 5 H 10 N 8 O 4 S, Orthorhombic, Pba 2 (no. 32), a = 7.7320(11) Å, b = 12.8686(19) Å, c = 5.0657(8) Å, β = 90°, V = 504.04(13) Å ³ , Z = 2, R gt ( F ) = 0.0298, w R ref ( F ² ) = 0.0748, T = 296(2) K.
Article
The 2‐hydrazinyl‐1,3‐benzothiazole derivatives are precursors for synthesis of several compounds of technological interest, including the Bt−NH−N=CHR1 (R1=alkyl, aryl, heteroaryl), derivatives. Usually when Bt−NH−NH2 is allowed to react with a benzenesulfonyl chloride the substitution is observed in the terminal nitrogen of the arenehydrazine unit, but when 4‐iodophenyl sulfonyl chloride (4‐IC6H4SO2Cl) was used, the product isolated was the title compound as confirmed by Rx‐analysis. Determination of the crystal structure revealed that the definition of the arrangement was driven by N−H⋅⋅⋅π, C−I⋅⋅⋅π and S2−O21⋅⋅⋅π interactions instead of the classic O⋅⋅⋅H−N hydrogen bonds. The interactions were confirmed by HS analysis. Interaction energy calculations showed that the π interactions‐based motifs play an important role in the supramolecular arrangement, contributing about 60 % to the total energy of the lattice. DFT calculations showed that the energy of the C−I⋅⋅⋅π dimer is complemented with contributions of π⋅⋅⋅π stacking and N−H⋅⋅⋅π interaction between the primary amine and the thiazole aromatic ring.
Article
A cyclic tetranuclear cobalt(III)/ (2) have been prepared and their molecular structures have been determined by X-ray crystallography [H 2 L 1 = N,N'-bis(3-methoxysalicylidene)-2,2-dimethyl-1,3-diaminoproane, H 2 L 2 = N,N'-bis(2-hydroxynaphthylmethylidene)propane-1,3-diamine]. Complex 1 contains two cobalt(III) and two sodium centers, while on the other hand, complex 2 contains a high-spin Co(II) and two terminal low-spin Co(III) centers in a Co III (S=0)-Co II (S=3/2)-Co III (S=0) trimer, as confirmed by DFT calculations Theoretical calculations have been used to analyze the importance of CH···π interactions involving the π-systems of the pseudohalide ligands. Indeed apart from the formation of conventional π···π stacking and CH···π(arene) interactions both complexes exhibit CH···π(pseudohalide) interactions that have been evaluated energetically by using mutated dimers and characterized by means of QTAIM and NCI plot computational methods which can be used to clarify interactions in real space.
Article
The scandium chloride complex LScCl(py)2 (L is bis[(2,4-di-tert-butyl)phenolato]-6,6′-(4,5-dihydroimidazol-2-ylidene)) containing the dianionic bis(phenolate)-tethered N-heterocyclic carbene (NHC) ligand was synthesized. The X-ray diffraction study demonstrated that the complex has a mononuclear structure with intramolecular coordination of the carbene moiety to the Sc3+ ion. In the presence of moist air, the NHC moiety is hydrolyzed, resulting in the formation of the chloride complex [L’ScCl(py)]2 with the dianionic tetradentate bis(phenolate) ligand containing the [NH(CH)2N(HC=O)] linker. The binuclear complex [L’ScClpy]2 is formed through the coordination of the oxygen atom of the formylethylenediamine moiety to the second Sc3+ ion.
Article
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The average value (μ) of a molecular dimension may be estimated by a weighted (\bar xw) or unweighted (\bar xu) mean. Computer simulations show that \bar xu can be used in hypothesis tests, since the distribution of (\bar xu - μ)/σ(\bar xu) is closely approximated by Student's t distribution. In contrast, hypothesis tests based on the weighted mean are inexact and potentially misleading.
Article
The Cambridge Structural Database contains the atomic coordinates of some 40000 organocarbon crystal structures. It is therefore likely to be a major source of data in future determinations of average molecular dimensions. From a statistical point of view, there is no single "optimum" method of obtaining such averages. Practical guidelines are suggested here on the basis of computer-simulation results.
Bonding with Bsp2 and Nsp2 coplanar (TBN = 0 i -15") predominates
  • See G Schmidt
  • R Boese
  • D Blaser
p(lc)-p(n) Bonding with Bsp2 and Nsp2 coplanar (TBN = 0 i -15") predominates. See G. Schmidt, R. Boese, and D. Blaser, Z. Naturforsch., 3. 84 observations range from 1.38 to 1.61 A and individual values depend on substituents on B and 0. For a discussion of borinic acid
  • Acltep Acbzpool
  • Balxob
  • Barriv
  • Bawgah
  • Belnip
  • Bepzeb
  • Biblaz Betute
  • Bicgez Bihxiz Birguelo
  • Bizjav Birhallo
  • Bogpoc
  • Bojler
  • Bopfer
  • Bovmee
  • Btupte
  • Bushay Bupsiblo
  • Butsue Buthazlo
  • Buwzuo
  • Bztppi
  • Casyok Cechex Cecxen Cedcuj Cehkab Celdom Cessau Cettaw Cetute Ceylun Cifzum Cihram Cilruk Cilsar Cimhip Cintey Cipbuy Cajmab
  • Cismum
ACBZPOOl ACLTEP ASAZOC BALXOB BAPPAJ BARRIV BAWFUA BAWGAH BECTAE BELNIP BEMLIO BEPZEB BETJOZ BETUTE 10 BIBLAZ BICGEZ BIHXIZ BIRGUElO BIRHALlO BIZJAV BOGPOC BOGSUL BOJLER BOJPUL BOPFER BOPFIV BOVMEE BQUINI BTUPTE BUDTEZ BUPSIBlO BUSHAY BUTHAZlO BUTSUE BUWZUO BZPRIB BZTPPI CAHJOK CAJMAB CANLUY CASSAQ CASTOF 10 CASYOK CECHEX CECXEN CEDCUJ CEHKAB CELDOM CESSAU CETTAW CETUTE CEYLUN CIFZUM CIHRAM CILRUK CILSAR CIMHIP CINTEY CIPBUY CISMUM J. Am. Chem. SOC., 1975, 97, 6729.
  • W B See
  • J D Schweizer
  • Dunitz
See W. B. Schweizer and J. D. Dunitz, Helv. Chim. Acta, 1982, 65, 1547.
  • R H See
  • Blessing
See R. H. Blessing, J. Am. Chem. SOC., 1983, 105, 2776.
Part 2, ch. 24. of each 'substitution' group. The 'mean of means' for the 9 subgroups is 1
  • F H See
  • S J Allen
  • J Rettig
  • Z Trotter
  • Wiley Rappoport
See F. H. Allen, Tetrahedron, 1982, 38, 2843. 1982, 37b, 1230. adducts see S. J. Rettig and J. Trotter, Can. J. Chem., 1982, 60, 2957. and Z. Rappoport, Wiley: New York, 1983, Part 2, ch. 24. of each 'substitution' group. The 'mean of means' for the 9 subgroups is 1.538 (0 = 0.022) A.
362-2.402) see DTHIBRlO (2.646), TPHOSI (2.695) see NBBZAM (1.843) see CIYFOF see
  • Br-Car
Br-Car (o-Br,) see TEACBR (2.362-2.402) see DTHIBRlO (2.646), TPHOSI (2.695) see NBBZAM (1.843) see CIYFOF see CISTED (2.366) see BEMLIO (2.206) see CIWYIQ (2.435, 2.453) see THINBR (2.321) see CIFZUM (2.508, 2.619) see BIZJAV (2.284)
  • P See
  • J D Chakrabarti
  • Dunitz
See P. Chakrabarti and J. D. Dunitz, Helv. Chim. Acta, 1982, 65, 1555.
  • See L Lebioda
See L. Lebioda, Acta Crystallogr., 1980, B36, 271.
  • F H See
  • A J Allen
  • Kirby
See F. H. Allen and A. J. Kirby, J. Am. Chem. SOC., 1984, 106, 6197.
  • D G Kennard
  • F H Watson
  • N W Allen
  • W D S Isaacs
  • R C Motherwell
  • W G Pettersen
  • Town
Kennard, D. G. Watson, F. H. Allen, N. W. Isaacs, W. D. S. Motherwell, R. C. Pettersen, and W. G. Town, 'Molecular Structures and Dimensions, vol. A l. Interatomic Distances 1960-1965,' Oosthoek Utrecht, 1972.
The Chemistry of Functional Groups. Supplement D: The Chemistry of Halides, Pseudohalides, and Azides' eds. S. Patai 5. Bonds which are endocyclic or exocyclic to any 3-or 4-membered rings have been omitted from all averages in this section
  • See M Kaftory
See M. Kaftory in 'The Chemistry of Functional Groups. Supplement D: The Chemistry of Halides, Pseudohalides, and Azides' eds. S. Patai 5. Bonds which are endocyclic or exocyclic to any 3-or 4-membered rings have been omitted from all averages in this section.
  • J Maki
Maki, J. Phys. Chem. Ref: Data, 1979, 8, 619.
P-F (N 2: P aromatic) 43 observations in range 1.409-1.770 in a wide variety of environments
  • F,-N-C In Hexafluorophosphate
  • Pf
F-N-C2 and F,-N-C in hexafluorophosphate, PF,(N -),P-F (N 2: P aromatic) 43 observations in range 1.409-1.770 in a wide variety of environments; F-S(6) in F,-SO,-C, (see FPSULF10, BETJOZ)
  • See B Fuchs
  • L Schleifer
  • E Tartakovsky
See B. Fuchs, L. Schleifer, and E. Tartakovsky, Noun J. Chim., 1984, 8, 275.
  • F H See
  • Allen
See F. H. Allen, Acta Crystallogr., 1984, B40, 64.
Cl-Te in range 2.34-2.60 see also longer bonds in BARRIV
  • Ci-Si-X Ci,-Si-X
CI-Si-X, (monochloro) CI,-Si-X, and C1,-Si-X Cl-Te in range 2.34-2.60 see also longer bonds in BARRIV, BOJPUL, CETUTE, EPHTEA, OPNTEClO (2.73- 2.94)
  • S C See
  • C H Nyburg
  • Faerman
See S. C. Nyburg and C. H. Faerman, J. Mol. Struct., 1986, 140, 347.
planar N 'v S aromatic in P 2: N 'v S N S in N=S=N and N=S=S see COJCUZ (1.830), DSEMORlO (1.846, see SEBZQI (1.805), NAPSEZlO (1.809, 1.820) see CISMUM (1.790, 1.791) see DMESIPO1
  • X-S-Nx Nsp
X-S-NX, Nsp': planar N 'v S aromatic in P 2: N 'v S N S in N=S=N and N=S=S see COJCUZ (1.830), DSEMORlO (1.846, see SEBZQI (1.805), NAPSEZlO (1.809, 1.820) see CISMUM (1.790, 1.791) see DMESIPO1, BOJLER, CASSAQ, C=N-S-X 1.852), MORTRSlO (1.841)
  • F H See
  • Allen
See F. H. Allen, (a) Acta Crystallogr., 1980, B36, 81; (b) 1981, B37, 890.
  • F H See
  • Allen
See F. H. Allen, Tetrahedron, 1982, 38, 645.
  • Org Chern
J, Org. Chern., 1983, 40, 5149. Z. Naturforsch., Teil B, 1984, 39, 139.
For longer bonds in B--CH, see LITMEBlO
  • Sample Dominated By B-Ch
Sample dominated by B-CH,. For longer bonds in B--CH, see LITMEBlO [B(4)-CH3 = 1.621-1.644A1.
  • Cisted Ciwyiq
  • Ciyfof Cmbidz Coddee Coddii Cofvoi Cojcuz Cosdix Cozpiq Cozviw Ctcnse Cucpiz Cudloc Cudlui Cugbah Cxmseo Dglyse Dmesipol Dsemorlo Dthibrlo
  • Ephtea Esears
  • Fmesib Fphtel Fpsulflo
  • Hmtiti Hclenelo
  • Hmtnti
  • Ibzdac
  • Mnpsil
  • Mophte Mortrslo
  • Nbbzam Napsezlo
  • Phascl Opnteclo
  • Pnposi Phasocol
  • Sebzqi
  • Teacbr Thinbr Tmpbti
  • Tpassn
  • Tphosi
  • Zcmxsp
CISTED CIWYIQ CIYFOF CMBIDZ CODDEE CODDII COFVOI COJCUZ COSDIX COZPIQ COZVIW CTCNSE CUCPIZ CUDLOC CUDLUI CUGBAH CXMSEO DGLYSE DMESIPOl DSEMORlO DTHIBRlO EPHTEA ESEARS ETEARS FMESIB FPHTEL FPSULFlO HCLENElO HMTITI HMTNTI HXPASC IBZDAC 1 1 IFORAM IODMAM IPMUDS ISUREAlO LITM EB 10 MESIAD METAMM MNPSIL MODIAZ MOPHTE MORTRSlO NAPSEZlO NBBZAM OPIMAS OPNTEClO PHASCL PHASOCOl PNPOSI SEBZQI SPSEBU TEACBR THINBR TMPBTI TPASSN TPASTB TPHOSI TTEBPZ ZCMXSP Z. Anorg. Allg. Chem., 1984, 511, 95. Inorg. Chem., 1984, 23, 1946. Znorg. Chem., 1984, 23, 1790.
Hencher in 'The Chemistry of the C-=C Triple Bond
  • J L See
See J. L. Hencher in 'The Chemistry of the C-=C Triple Bond,' ed. S. Patai, Wiley, New York, 1978, ch. 2. 16. Conjugated: torsion angle about central C-C single bond is 0 _+ 20" (cis) or 180 f 20" (trans).
  • R R See
  • J A Holmes
  • J Deiters
  • Amer
See R. R. Holmes and J. A. Deiters, J. Amer. Chem. SOC., 1977,99, 3318.
  • See A Kalman
  • M Czugler
  • G Argay
See A. Kalman, M. Czugler, and G. Argay, Acta Crystallogr., 1981, B37, 868.
  • L See
  • H.-B Norskov-Lauritsen
  • P Burgi
  • H R Hoffmann
  • Schmidt
See L. Norskov-Lauritsen, H.-B. Burgi, P. Hoffmann, and H. R. Schmidt, Helv. Chim. Acta, 1985, 68, 76.
  • Acta Chem
  • Scand
  • A Ser
Acta Chem. Scand., Ser A, 1983, 37, 219. Z. Naturforsch., Teil B, 1981, 36, 922. Inorg. Chem., 1978, 17, 894. Znorg. Chem., 1983, 22, 1809. Chem. Z, 1983, 107, 169. Tetrahedron Lett., 1983, 24, 4337.
  • J Kennard
  • Chem
. Taylor and 0. Kennard, J. Chem. Inf: Comp. Sci., 1986, 26, 28.
3. 84 observations range from 1.38 to 1.61 A and individual values
  • See G Schmidt
  • R Boese
  • D Blaser
p(lc)-p(n) Bonding with Bsp2 and Nsp2 coplanar (TBN = 0 i -15") predominates. See G. Schmidt, R. Boese, and D. Blaser, Z. Naturforsch., 3. 84 observations range from 1.38 to 1.61 A and individual values depend on substituents on B and 0. For a discussion of borinic acid
Bonds which are endocyclic or exocyclic to any 3-or 4-membered rings have been omitted from all averages in this section. 6. The overall average given here is for Csp3-Csp3 bonds which carry only C or H substituents
  • See M Kaftory
See M. Kaftory in 'The Chemistry of Functional Groups. Supplement D: The Chemistry of Halides, Pseudohalides, and Azides' eds. S. Patai 5. Bonds which are endocyclic or exocyclic to any 3-or 4-membered rings have been omitted from all averages in this section. 6. The overall average given here is for Csp3-Csp3 bonds which carry only C or H substituents. The value cited reflects the relative abundance
Part 2, ch. 24. of each 'substitution' group. The 'mean of means
  • F H See
  • S J Rettig
  • J Trotter
  • Z Rappoport
See F. H. Allen, Tetrahedron, 1982, 38, 2843. 1982, 37b, 1230. adducts see S. J. Rettig and J. Trotter, Can. J. Chem., 1982, 60, 2957. and Z. Rappoport, Wiley: New York, 1983, Part 2, ch. 24. of each 'substitution' group. The 'mean of means' for the 9 subgroups is 1.538 (0 = 0.022) A.
bond and on nature of substituent C atoms; these effects are ignored here. 40. N pyramidal has average angle at N in range 100-113
  • N-N Bond
N-N bond length also dependent on torsion angle about N-N bond and on nature of substituent C atoms; these effects are ignored here. 40. N pyramidal has average angle at N in range 100-113.5"; N planar has average angle of 2 117.5".
No detectable variation in S=O bond length with type of C-substituent
  • R R See
  • J A Holmes
  • Deiters
See R. R. Holmes and J. A. Deiters, J. Amer. Chem. SOC., 1977,99, 3318. 42. No detectable variation in S=O bond length with type of C-substituent.
  • F H Allen
  • S Bellard
  • M D Brice
  • B A Cartwright
  • A Doubleday
  • H Higgs
  • T Hummelink
  • B G Hummelink-Peters
  • W D S Kennard
  • J R Motherwell
  • D G Rodgers
  • Watson
F. H. Allen, S. Bellard, M. D. Brice, B. A. Cartwright, A. Doubleday, H. Higgs, T. Hummelink, B. G. Hummelink-Peters, 0. Kennard, W. D. S. Motherwell, J. R. Rodgers, and D. G. Watson, Acta Cryslallogr., 1979, B35, 2331.
  • D G Kennard
  • F H Watson
  • N W Allen
  • W D S Isaacs
  • R C Motherwell
  • W G Pettersen
  • Town
Kennard, D. G. Watson, F. H. Allen, N. W. Isaacs, W. D. S. Motherwell, R. C. Pettersen, and W. G. Town, 'Molecular Structures and Dimensions, vol. A l. Interatomic Distances 1960-1965,' Oosthoek Utrecht, 1972.
  • M D Harmony
  • V W Laurie
  • R L Kuczkowski
  • R H Schwendemann
  • D A Ramsay
  • F J Lovas
  • W J Lafferty
  • A G Maki
M. D. Harmony, V. W. Laurie, R. L. Kuczkowski, R. H. Schwendemann, D. A. Ramsay, F. J. Lovas, W. J. Lafferty, and A. G. Maki, J. Phys. Chem. Ref: Data, 1979, 8, 619.
  • R Taylor
  • Kennard
R. Taylor and 0. Kennard, Acta Crystallogr., 1983, B39, 517.