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Substituent-Dependent Coordination Modes of 1-Methyl-5-R-tetrazoles in Their Cupric Chloride Complexes
Abstract
A series of cupric chloride complexes with 1-methyl-5-R-tetrazole ligands, where R = NH 2 , t-Bu, Ph, MeS, CH[dbnd]CH 2 , MeSO 2 , were synthesized by interaction of CuCl 2 ·2H 2 O with the above ligands L NH 2 , L tBu , L Ph , L MeS , L Vin , and L MeSO 2 , respectively. The obtained complexes [Cu(L NH 2 ) 3 Cl 2 ]·H 2 O (1), [Cu(L tBu ) 2 Cl 2 ] (2), [Cu(L Ph ) 2 Cl 2 ] (3), [Cu(L MeS ) 2 Cl 2 ] (4), [Cu(L Vin )Cl 2 ] n (5), and [Cu(L MeSO 2 )(H 2 O)Cl 2 ] n (6) were characterized by single crystal X-ray analysis. The effect of C ⁵ -substituent on coordination modes of tetrazole ligands and structural motifs of complexes was observed. Complexes 1–4 are mononuclear, with the tetrazole ring N ⁴ coordination. Complex 5 presents 1D coordination polymer, formed at the expense of triple bridge between two neighboring copper(II) cations (double chlorido bridge and the tetrazole ring N ³ ,N ⁴ -bridge). In 6, being also 1D coordination polymer, coordination chains are composed of alternating Cu(L MeSO 2 ) 2 and Cu(H 2 O) 2 fragments linked by double chlorido bridges. Ligand L MeSO 2 shows N ³ coordination, being rare among 1,5-disubstituted tetrazoles. The influence of the nature of C ⁵ substituents on coordination features of the obtained complexes is discussed by using quantum-chemical calculations of the electronic structure and basicity of the ligands.
... The XANES and EXAFS spectra obtained for these compounds are shown in Figure 4a 6 show the k 2 -weight EXAFS spectra fitted with the EXCURVE program [24], with the Δk ranging from 3 to 11 Å −1 . The initial models of the EXAFS spectra were based on the XRD data for the mononuclear Cu(L 1 )2Br2 complex and cupric chloride complex representing a 1D coordination polymer, which was formed at the expense of the triple bridge between two neighbouring copper(II) cations (double chlorido bridge and the tetrazole ring N3,N4-bridge) [25]. EXAFS fitting results are presented in Table 2 for complex 3 and in Table 3 for 4. Note that the EXAFS allow us to determine average coordination numbers, interatomic distances, and Debye-Waller factors for the scattering atom (Cu). ...
... 6 show the k 2 -weight EXAFS spectra fitted with the EXCURVE program [24], with the ∆k ranging from 3 to 11 Å −1 . The initial models of the EXAFS spectra were based on the XRD data for the mononuclear Cu(L 1 ) 2 Br 2 complex and cupric chloride complex representing a 1D coordination polymer, which was formed at the expense of the triple bridge between two neighbouring copper(II) cations (double chlorido bridge and the tetrazole ring N3,N4-bridge) [25]. EXAFS fitting results are presented in Table 2 for complex 3 and in Table 3 for 4. Note that the EXAFS allow us to determine average coordination numbers, interatomic distances, and Debye-Waller factors for the scattering atom (Cu). ...
... show the k 2 -weight EXAFS spectra fitted with the EXCURVE progr [24], with the Δk ranging from 3 to 11 Å −1 . The initial models of the EXAFS spectra w based on the XRD data for the mononuclear Cu(L 1 )2Br2 complex and cupric chloride co plex representing a 1D coordination polymer, which was formed at the expense of triple bridge between two neighbouring copper(II) cations (double chlorido bridge and tetrazole ring N3,N4-bridge) [25]. EXAFS fitting results are presented in Table 2 for comp 3 and in Table 3 for 4. Note that the EXAFS allow us to determine average coordinat numbers, interatomic distances, and Debye-Waller factors for the scattering atom (Cu). ...
New coordination compounds of copper(II) with 2,5-bis(ethylthio)-1,3,4-thiadiazole (L1) and 2,5-bis(pyridylmethylthio)-1,3,4-thiadiazole (L2) with compositions Cu(L1)2Br2, Cu(L1)(C2N3)2, Cu(L2)Cl2, and Cu(L2)Br2 were prepared. The complexes were identified and studied by CHN analysis, infrared (IR) spectroscopy, powder X-Ray diffraction (XRD), and static magnetic susceptibility. The crystal structures of Cu(II) complexes with L1 were determined. The structures of the coordination core of complexes Cu(L2)Cl2 and Cu(L2)Br2 were determined by Extended X-ray absorption fine structure (EXAFS) spectroscopy. Magnetization measurements have revealed various magnetic states in the studied complexes, ranging from an almost ideal paramagnet in Cu(L1)2Br2 to alternating-exchange antiferromagnetic chains in Cu(L1)(C2N3)2, where double dicyanamide bridges provide an unusually strong exchange interaction (J1/kB ≈ −23.5 K; J2/kB ≈ −20.2 K) between Cu(II) ions. The cytotoxic activity of copper(II) complexes with L2 was estimated on the human cell lines of breast adenocarcinoma (MCF-7) and hepatocellular carcinoma (HepG2).
Water-insoluble polyelectrolyte complexes of cellulose acetate sulphate in the form of sodium salt (Na-CAS) and aminoglycoside antibiotic (AB) kanamycin (KAN) were obtained by mixing of the components aqueous solutions. The composition of the complexes was determined in accordance with the medium pH and mixing order. The increase of Na‑CAS cellobiose units per mole of AB has been shown to correlate with the decrease of pH value. The complex formation was studied by Fourier transform infrared spectroscopy, thermal analysis, X-ray analysis, laser diffraction, motion trajectory of nanoparticles analysis and scanning electron microscopy. Quantum-chemical study of the relative stability of the protonated forms of KAN in aqueous solution was performed to determine the preferred protonation sites of KAN molecule. The pKa values of KAN were calculated by means of isodesmic reactions method. The structures and binding energy for the KAN dimer and the KAN – CAS complex were also investigated by quantum-chemical methods. Na‑CAS – KAN complex itself and immobilised on the activated carbon was shown to demonstrate in vitro two times antibacterial activity of the standard (injectable) form of KAN against Mycobacterium tuberculosis. It can be recommended for in vivo clinical trials as a new form of aminoglycoside AB for oral administration.
In this chapter, the tetrazoles investigations between 2009 and 2019 are summarized. Emphasis is made on the publications reported in 2017–18. The attention is focused on the most important events of tetrazole chemistry such as use of new catalysts, promoters and other experimental conditions favoring processes allowing the formation and functionalization of tetrazole ring. The focus is placed on the development of safe and eco-friendly methods to access tetrazoles. A special section of the review is devoted to the coordination chemistry of tetrazole, which is developing recently. The most important achievements reporting the use of tetrazoles as energetic materials and in medicinal chemistry are highlighted. Strategic directions that predict the tetrazole chemistry for the next decade have been underlined.
The complex [Cu(5-(N,N-dimethylaminomethyl)-1-(pyridin-2-yl)tetrazole)Cl2]n (1) was prepared by the reaction of 5-(N,N-dimethylaminomethyl)-1-(pyridin-2-yl)tetrazole with copper(II) chloride in solution. According to the single crystal X-ray analysis, complex 1 presents a 1D coordination polymer, formed at the expense of single chlorido bridges between neighboring pentacoordinated copper(II) cations. The tetrazole acts as a chelating ligand, coordinated via the heteroring N⁴ atoms and the nitrogen atom of the amino group. The temperature-dependent magnetic susceptibility measurements of complex 1, as well as previously described chain coordination polymers [Cu(1-methyl-5-vinyltetrazole)Cl2]n (2) and [Cu2(1-methyl-5-methylsulfonyltetrazole)2(H2O)2Cl4]n (3), revealed that the copper(II) ions are antiferromagnetically coupled in all the complexes. A superexchange pathway between the metal cations in complex 2 is provided at the expense of double chlorido bridges and the tetrazole ring N³,N⁴-bridges. In complex 3, this pathway is provided by double chlorido bridges which link alternating Cu(1-methyl-5-methylsulfonyltetrazole)2 and Cu(H2O)2 fragments.
1,3-Bis(1-methyl-1H-tetrazol-5-yl)propane (bmtp) was prepared by a procedure including regioselective tert-butylation of 1,3-bis(1H-tetrazol-5-yl)propane and exhaustive methylation of the obtained 1,3-bis(2-tert-butyl-1H-tetrazol-5-yl)propane, followed by removal of the tert-butyl group from the tetrazolium salt under acidic conditions. The ligand bmtp reacts with CuCl2·2H2O in ethanol to give the complexes [Cu3(bmtp)2Cl6(H2O)2]n and [Cu(bmtp)Cl2]n. The transformation of [Cu(bmtp)Cl2]n into [Cu3(bmtp)2Cl6(H2O)2]n is observed in ethanol. According to single crystal X-ray analysis, [Cu(bmtp)Cl2]n was obtained as a mixture of polymorphic forms. They are all 1D coordination polymers, in which polymeric chains include Cu2Cl4 units linked to each other by two bridging ligands via the tetrazole ring N⁴ atoms. [Cu3(bmtp)2Cl6(H2O)2]n presents a 2D coordination polymer, including Cu3Cl6 units bonded to four others by ligand molecules. In this complex, the tetrazole ligands show monodentate N⁴ and bridging N³,N⁴ coordination. The temperature-dependent magnetic susceptibility measurements of this complex revealed that the copper(II) ions are antiferromagnetically coupled, showing a coupling constant J of −4.0 cm⁻¹.
Complex [Cu(tbt)Cl2]n (tbt = 1‐tert‐butyl‐1H‐tetrazole) was prepared by reaction of tbt with copper(II) chloride in solution. According to single‐crystal X‐ray analysis, this complex presents 1D coordination polymer, formed at the expense of double chlorido bridges between neighboring pentacoordinate copper(II) cations. 1‐tert‐Butyl‐1H‐tetrazole acts as monodentate ligand coordinated by CuII cations via the heteroring N4 atoms. The temperature‐dependent magnetic susceptibility measurements of novel complex [Cu(tbt)Cl2]n as well as described previously 1D coordination polymer [Cu(tbt)2Cl2]n, and linear trinuclear complex [Cu3(tbt)6Br6], were carried out. Magnetic studies revealed that the copper(II) ions were weakly ferromagnetically coupled in polymeric copper(II) chloride complexes, whereas complex [Cu3(tbt)6Br6] showed antiferromagnetic coupling.
The interaction of 1-R-tetrazole-5-thiols with copper(II) chloride in solution was found to yield crystalline tetrazole complexes [CuCl2L2]n (L is 1-R-tetrazole, R = Me, Et, Bu) and [CuCl2L2]n·nMeCN (L is 1-phenyltetrazole). The observed transformation of 1-R-tetrazole-5-thiols into 1-R-tetrazoles presents the first examples of desulfurization of tetrazole-5-thiols under complexation. A possible pathway of desulfurization of 1-R-tetrazole-5-thiols is proposed. It includes initial oxidation of tetrazole-5-thiols by copper(II) ions into bis(tetrazol-5-yl)disulfanes, followed by copper-assisted oxidation by air oxygen. Obtained complexes [CuCl2L2]n and [CuCl2L2]n·nMeCN were found to be coordination polymers, 2D and 1D, respectively. In all them, 1-R-tetrazoles act as monodentate ligands coordinated to the metal via the tetrazole ring N⁴ atom, whereas chlorine atoms provide bidentate bridging coordination to generate polymeric structure.
2-(1H-Tetrazol-1-yl)thiazole (tth), prepared by heterocyclization of 2-aminothiazole with triethyl orthoformate and sodium azide, was found to react with copper(II) chloride in ethanol giving a mixture of [Cu(tth)2Cl2]n (1) and [Cu2(ethc)2Cl4]·2H2O (2), where ethc is ethyl thiazol-2-ylcarbamimidate. Formation of complex 2 with ethc ligand can be explained by tetrazole ring-opening reaction of tth followed by addition of ethanol to the intermediate N-(thiazol-2-yl)cyanamide (N-tca). This assumption was confirmed by isolation of complex 2 under interaction of N-tca with copper(II) chloride in ethanol. Transformation of the tetrazole ring was not observed under interaction of tth and copper(II) chloride in 1,2-dichloroethane/ethanol mixture, when 1 and [Cu2(tth)4Cl4] (3) were isolated. Ligand tth was found to react with copper(II) tetrafluoroborate and cobalt(II) chloride giving [Cu(tth)2(H2O)4](BF4)2 (4) and [Co(tth)2Cl2(H2O)2]·2tth (5), correspondingly. Molecular crystals of tth and complexes 1–5 were characterized by X-ray single crystal analysis. In the complexes, tth acts as a monodentate ligand coordinated via the tetrazole ring N⁴ atom.
Given the fact that the traditional cryogenic rectification is highly energy and capital intensive during the purification of xenon, effectively selective adsorption of xenon over other noble gases at room temperature using porous materials is a critical and urgent issue. Here we present a flexible zinc tetrazolate framework ([Zn(mtz)2]), which exhibits high capture capacity of xenon and selective adsorption of xenon over other noble gases at room temperature. Due to its high adsorption enthalpy for xenon, the suitable pore size that matches well with xenon atom, as well as the high polarizability of Xe, [Zn(mtz)2] shows breathing behaviour on xenon adsorption, which is confirmed by experimental adsorption isotherms of xenon and thermodynamic analysis of breathing transition. Isosteric heats of adsorption and S(DIH) calculations indicates that [Zn(mtz)2] has significantly higher adsorption affinity and capacity for Xe compared with Kr, Ar and N2. The high capture capacity of Xe (2.7 mmol/g) in idealized PSA process and high Xe/Kr selectivity (15.5) from breakthrough experiment promise its potential application for Xe capture and separation in Xe-Kr gas mixture.
SIR2014 is the latest program of the SIR suite for crystal structure solution of small, medium and large structures. A variety of phasing algorithms have been implemented, both ab initio (standard or modern direct methods, Patterson techniques, Vive la Différence) and non-ab initio (simulated annealing, molecular replacement). The program contains tools for crystal structure refinement and for the study of three-dimensional electron-density maps via suitable viewers.
The improvements in the crystal structure refinement program SHELXL have been closely coupled with the development and increasing importance of the CIF (Crystallographic Information Framework) format for validating and archiving crystal structures. An important simplification is that now only one file in CIF format (for convenience, referred to simply as `a CIF') containing embedded reflection data and SHELXL instructions is needed for a complete structure archive; the program SHREDCIF can be used to extract the .hkl and .ins files required for further refinement with SHELXL. Recent developments in SHELXL facilitate refinement against neutron diffraction data, the treatment of H atoms, the determination of absolute structure, the input of partial structure factors and the refinement of twinned and disordered structures. SHELXL is available free to academics for the Windows, Linux and Mac OS X operating systems, and is particularly suitable for multiple-core processors.
The irreversible reaction of methyl triflate with the neutral Re(I) tetrazolato complexes of the type fac-[Re(diim)(CO)3(L)], where diim is either 1,10-phenanthroline or 2,2’-bipyridine and L is a para substituted 5-aryltetrazolate, yielded the corresponding cationic methylated complexes. While methylation occurred regioselectively at the position N4 of the tetrazole ring, the cationic complexes were found to exist in solution as an equilibrating mixture of linkage isomers, where the Re(I) centre was bound to either the N1 or N2 atom of the tetrazole ring. The existence of these isomers was highlighted both by NMR and X-ray crystallography studies. On the other hand, the two isomers resulted indistinguishable by means of IR, UV-Vis and luminescence spectroscopy. The prepared cationic complexes are all brightly phosphorescent in fluid and rigid solutions, with emission originating from triplet metal-to-ligand charge transfer excited states. Compared to their neutral precursors, which are emitting from admixtures of triplet metal-to-ligand and ligand-to-ligand charge transfer states, the methylated complexes exhibit blue-shifted emission characterised by elongated excited state lifetimes and increased quantum yields. The nature of the excited states for both the neutral and methylated complexes was probed by means of Raman and transient Raman spectroscopy and with the aid of Time-Dependent Density Functional Theory calculations. Lastly, both the neutral and methylated species were used as emitting phosphors in the fabrication or Organic Light Emitting Devices and Light Emitting Electrochemical Cells.
The past decade has witnessed intense research activity in the area of FeII spin crossover coordination polymers, which are structurally diverse and functionally intriguing materials. In this endeavor, a less exploited series of ligands have been selected among various N-donor
triazole and tetrazole molecules. Developing conventions that allow the tailoring of such functional materials with predictable architecture and properties is an important objective and current interest in crystal engineering. However, detailed knowledge on the structure–property correlation
is still scanty due to the small number of crystal structures of such compounds. The principal focus is to decipher the effect of various supramolecular factors such as intermolecular interactions, hydrogen bonding etc., on the resultant FeII coordination polymers. This tutorial
review aims at highlighting some of the developments of such structurally diverse and functionally intriguing 1D polymeric chains, 2D and 3D networks built from triazole or tetrazole ligands exhibiting fascinating spin crossover phenomena.
We present a new integral equation formulation of the polarizable continuum model (PCM) which allows one to treat in a single approach dielectrics of different nature: standard isotropic liquids, intrinsically anisotropic medialike liquid crystals and solid matrices, or ionic solutions. The present work shows that integral equation methods may be used with success also for the latter cases, which are usually studied with three-dimensional methods, by far less competitive in terms of computational effort. We present the theoretical bases which underlie the method and some numerical tests which show both a complete equivalence with standard PCM versions for isotropic solvents, and a good efficiency for calculations with anisotropic dielectrics.
1-tert-Butyl-1H-1,2,4-triazole (tbtr) was found to react with copper(II) chloride or bromide to give the complexes [Cu(tbtr)2X2]n and [Cu(tbtr)4X2], where X = Cl, Br. 1-tert-Butyl-1H-tetrazole (tbtt) reacts with copper(II) bromide resulting in the formation of the complex [Cu3(tbtt)6Br6]. The obtained crystalline complexes as well as free ligand tbtr were characterized by elemental analysis, IR spectroscopy, thermal and X-ray analyses. For free ligand tbtr, 1H NMR and 13C NMR spectra were also recorded. In all the complexes, tbtr and tbtt act as monodentate ligands coordinated by CuII cations via the heteroring N4 atoms. The triazole complexes [Cu(tbtr)2Cl2]n and [Cu(tbtr)2Br2]n are isotypic, being 1D coordination polymers, formed at the expense of single halide bridges between neighbouring copper(II) cations. The isotypic complexes [Cu(tbtr)4Cl2] and [Cu(tbtr)4Br2] reveal mononuclear centrosymmetric structure, with octahedral coordination of CuII cations. The tetrazole compound [Cu3(tbtt)6Br6] is a linear trinuclear complex, in which neighbouring copper(II) cations are linked by single bromide bridges.
Based on the same in situ formed ligand, two new MOFs, namely {[Zn2(HL)2]·0.5DMF·H2O}n (1) and {[Cd2(HL)2]·1.5H2O}n (2) (H3L = 5-[(2H-tetrazol-5-yl)amino]isophthalic acid), have been solvothermally synthesized and structurally characterized by elemental analysis, IR, PXRD, and single-crystal X-ray diffraction. During the self-assembly process, the original ligand H2ATBDC (5-(5-amino-1H-tetrazol-1-yl)-1,3-benzenedicarboxylic acid) undergoes the Dimroth rearrangement to form a new ligand H3L, consequently contributing to the construction of the two new MOFs. Structural analysis reveals that both 1 and 2 possess a three-directional intersecting channel system and pts topology. The major structural difference between them is the metal coordination, which displays four- and six-coordinated modes in 1 and 2, respectively, and results in diverse channels and different stabilities. Moreover, the adsorption properties of 1a (i.e., the desolvated 1) have been studied, and the results show that 1a possesses moderate capability of gas sorption for N2, CO2, and CH4 gases, along with high selectivity ratios of 102 and 20 for CO2/N2 (15 : 85) and CO2/CH4 (50 : 50) at 273 K, respectively.
Zirconium (Zr) metal-organic frameworks (MOFs) have received considerable interest due to their superior hydrolytic, thermal, and chemical stability. On the basis of 40 topological nets, 120 Zr-MOFs with 8-, 10-, and 12-coordination are designed in this study with nitrogen-rich CO2-philic tetrazolate toward CO2 capture. The Zr-Tetrazolate MOFs are revealed to exhibit substantially stronger CO2 adsorption than their carboxylate counterparts of identical topologies. By synergizing multiscale modeling from molecular simulation to breakthrough prediction, MOF-eft-P is identified among the 120 Zr-MOFs to possess the largest isosteric heat at infinite dilution and uptake at 1 bar for CO2, as well as the highest CO2/N2 selectivity; it outperforms many typical MOFs and other adsorbents reported in the literature. The breakthrough time of CO2 in MOF-eft-P is predicted to be 25 min and significantly longer than that of N2, indicating excellent CO2/N2 separation. This study demonstrates the bottom-up strategy to design Zr-MOFs and suggests MOF-eft-P to be an interesting candidate for CO2 capture.
To evaluate the 5-substituted tetrazolate (5R-tetrazolate) ligand for the development of novel antitumor active Pt(II) and Pt(IV) diamines, eight analogues of transplatin bearing 5-phenyltetrazolato and 5-(phenol)tetrazolato ligands were prepared by reacting transplatin with the 5-substituted tetrazolate in DMF in the presence of trimethylamine. Coordination to platinum was through the N2 position of the tetrazolato ligand, as evidenced by a X-ray crystal structure of trans-diamminobis[5-(phenyl-4-ol)tetrazolato-κN²]platinum(II). Attempts to synthesize the corresponding cis-coordinated analogues from cisplatin were unsuccessful due to isomerization to the more stable trans isomers. Hydrogen peroxide was used to oxidize trans-diamminobis(5-phenyltetrazolato) and trans-diamminobis(5-phenoltetrazolato)platinum(II) complexes to the trans-dihydroxo-Pt(IV) analogues; the hydroxo ligands were then further acylated. The binding of Pt to calf thymus DNA for trans,trans,trans-diamminodihydroxidobis(5-phenyltetrazolato-κN²)platinum(IV) was dependent on the presence of ascorbate; however, the Pt(II) analogue trans-diamminobis(5-phenyltetrazolato-κN²)platinum(II) itself bond only very weakly to DNA, indicating that this is not the product of the ascorbate induced reduction of the Pt(IV) complex. Evaluation of the antiproliferative activity on eight human cancer cells in vitro showed the Pt(IV) complexes to be more potent than the Pt(II) analogues but all complexes were still much less active than cisplatin. No cross resistance to cisplatin was observed in the A2870 ovarian cancer cell line.
R-2H-Tetrazol-5-ylacetic acids (abbreviated as 2-R-taa; R = Me, iPr, tBu) react with K2[PtCl4] in 1 m HCl in H2O at r.t. furnishing trans-platinum(II) complexes trans-[PtCl2(2-R-taa)2] (1–3), whereas cis-isomeric species cis-[PtCl2(2-R-taa)2] (R = iPr, 4; tBu, 5) are isolated at lower temperature (4–6 °C). In the presence of EtOH in the reaction mixture, esterification of the tetrazol-5-ylacetoxy group of 2-tBu-taa leads to trans-[PtCl2(ethyl 2-tert-butyl-2H-tetrazol-5-ylacetate)2] (6). Complexes 1–6 were characterized by elemental analyses (CHN), HRESI+-MS, 1H, 13C{1H}, 195Pt{1H} NMR and IR spectroscopy, differential scanning calorimetry/thermogravimetry (DSC/TG), and X-ray diffraction (for 1·H2O, 2, 3·2H2O, 4, 5·2H2O, and 6). The generation of the tetrazole-based complexes in solution (1 m DCl in D2O, 25 °C) was studied by 1H NMR spectroscopy and HPLC-MS. The obtained data indicate the initial formation of anionic [PtCl3(2-R-taa)]– complexes that are subsequently converted into disubstituted isomeric platinum(II) species cis- and trans-[PtCl2(2-R-taa)2]. By contrast to cis- and trans-[PtCl2(2-R-taa)2] that were inactive in two human cancer models in vitro (IC50 > 100 µm), complex 6 demonstrated noticeable antiproliferative effects in HT-29 colon and MCF-7 breast carcinoma cell lines with IC50 values of 14.2 ± 1.1 and 5.8 ± 1.2 µm, respectively.
High-connected crystalline porous materials are rare but promising for gas adsorption and separation since various pore shape and size as well as high framework stability may be achieved by tuning the framework connectivity. We demonstrate herein two high-connected frameworks, namely, {[Cd7(BDC)6(MTAZ)2(DMF)6]·3DMF}n (SNNU-11) and {[Cd5(BDC)(PTAZ)8(DMF)2]·4DMF}n (SNNU-12) (BDC = 1,4-benzenedicarboxylic acid, MTAZ = 5-methyl-tetrazole and PTAZ = 5-(4-pyridyl)-tetrazole). In SNNU-11, BDC ligands link S-shaped [Cd7(MTAZ)2] motifs to form a novel 10-connected framework, which is related but different to the reported 10-connected bct and gpu nets. Under the similar synthesis condition, the utilization of 5-(4-pyridyl)-tetrazole produced SNNU-12, which is constructed from zigzag Cd5 clusters and exhibits a 12-connected fcu net. Notably, SNNU-12 decorated with uncoordinated nitrogen sites shows not only high CO2 uptake capacity (87.9 cm3 g-1, 1 atm and 273K) but also high CO2 over CH4 and C2 hydrocarbons over CH4 selectivity, which is among the highest values of high-connected MOF materials (connectivity ≥ 10) including famous UiO-66 and rare-earth fcu-MOFs under the same temperature and pressure.
1-(5-Amino-3-azapentyl)tetrazole dihydrochloride (HL·2HCl) was prepared by heterocyclization of diethylenetriamine with triethyl orthoformate and sodium azide followed by treatment with potassium carbonate and hydrochloric acid. The reaction of CuCl2, HL·2HCl and triethylamine (NEt3) in a molar ratio of 1 : 1 : 3 in water was found to generate a novel organometallic tetrazole derivative Cu2L2Cl2. This compound is present as a binuclear centrosymmetric molecular complex, in which C-deprotonated tetrazole L acts as a chelating ligand via the two amino N and tetrazole ring C coordination sites and the two copper atoms are linked together through two tetrazole ring N(4)-C(5) bridges. This complex is the first organocopper tetrazole derivative. When the molar ratio of the reagents in the abovementioned reaction was changed to 1 : 2 : 2, the complex Cu(HL)2Cl2 was formed along with Cu2L2Cl2. Pure Cu(HL)2Cl2 was isolated after reaction of the reagents in a molar ratio of 1 : 3 : 6. The complex Cu(HL)2Cl2 is present as a mononuclear molecular complex, with a chelating coordination mode of HL via the two amino N atoms only. Both complexes as well as HL·2HCl were characterized by single-crystal X-ray analysis.
2-(1H-Tetrazol-5-yl)pyridine (L) has been reacted separately with Me2NCH2CH2Cl⋅HCl and ClCH2CH2OH to yield two regioisomers in each case, N,N-dimethyl-2-[5-(pyridin-2-yl)-1H-tetrazol-1-yl]ethanamine (L1)/N,N-dimethyl-2-[5-(pyridin-2-yl)-2H-tetrazol-2-yl]ethanamine (L2) and 2-[5-(pyridin-2-yl)-1H-tetrazol-1-yl]ethanol (L3)/2-[5-(pyridin-2-yl)-2H-tetrazol-2-yl]ethanol (L4), respectively. These ligands, L1–L4, have been coordinated with CuCl2⋅H2O in 1 : 1 composition to furnish the corresponding complexes 1–4. EPR Spectra of Cu complexes 1 and 3 were characteristic of square planar geometry, with nuclear hyperfine spin 3/2. Single X-ray crystallographic studies of 3 revealed that the Cu center has a square planar structure. DNA binding studies were carried out by UV/VIS absorption; viscosity and thermal denaturation studies revealed that each of these complexes are avid binders of calf thymus DNA. Investigation of nucleolytic cleavage activities of the complexes was carried out on double-stranded pBR322 circular plasmid DNA by using a gel electrophoresis experiment under various conditions, where cleavage of DNA takes place by oxidative free-radical mechanism (OH⋅). In vitro anticancer activities of the complexes against MCF-7 (human breast adenocarcinoma) cells revealed that the complexes inhibit the growth of cancer cells. The IC50 values of the complexes showed that Cu complexes exhibit comparable cytotoxic activities compared to the standard drug cisplatin.
1-(tert-Butyl)-1H-tetrazole () reacts with copper(ii) tetrafluoroborate hexahydrate to give the complexes [Cu2L8(H2O)2](BF4)4 () or [Cu3L6(H2O)6](BF4)6 () depending on the reaction conditions. These complexes, as well as compound , were characterized using single crystal X-ray analysis. Complex was found to comprise a dinuclear complex cation [Cu2L8(H2O)2](4+) (the Ci symmetry point group), with six tetrazole ligands L showing monodentate N(4)-coordination, and two ligands L providing two tetrazole ring N(3),N(4) bridges between the copper(ii) cations; water molecules complete the distorted octahedral coordination of the metal ions. Complex includes a linear trinuclear complex cation [Cu3L6(H2O)6](6+) (the S6 symmetry point group), in which neighbouring copper(ii) cations are linked by three ligands L via tetrazole ring N(3),N(4) bridges; central and terminal metal ions show octahedral CuN6 and CuN3O3 coordination cores, respectively. The temperature-dependent magnetic susceptibility measurements of complex revealed that the copper(ii) ions were weakly ferromagnetically coupled showing a coupling constant J of 2.2 cm(-1) {H = -2J(S1S2 + S2S3)}. The quantum-chemical investigation of the electronic structure and basicity of ligand L was carried out.
Capping agents play an important role in the colloidal synthesis of nanomaterials because they control the nucleation and growth of particles, as well as their chemical and colloidal stability. During recent years tetrazole derivatives have proven to be advanced capping ligands for the stabilization of semiconductor and metal nanoparticles. Tetrazole-capped nanoparticles can be prepared by solution-phase or solventless single precursor approaches using metal derivatives of tetrazoles. The solventless thermolysis of metal tetrazolates can produce both individual semiconductor nanocrystals and nanostructured metal monolithic foams displaying low densities and high surface areas. Alternatively, highly porous nanoparticle 3D assemblies are achieved through the controllable aggregation of tetrazole-capped particles in solutions. This approach allows for the preparation of non-ordered hybrid structures consisting of different building blocks, such as mixed semiconductor and metal nanoparticle-based (aero)gels with tunable compositions. Another unique property of tetrazoles is their complete thermal decomposition, forming only gaseous products, which is employed in the fabrication of organic-free semiconductor films from tetrazole-capped nanoparticles. After deposition and subsequent thermal treatment these films exhibit significantly improved electrical transport. The synthetic availability and advances in the functionalization of tetrazoles necessitate further design and study of tetrazole-capped nanoparticles for various applications.
1-(Furan-2-ylmethyl)-1H-tetrazole (fmt), prepared by heterocyclization of furfurylamine with triethyl orthoformate and sodium azide, was found to react with copper(II) perchlorate, nitrate, and bromide giving complexes [Cu(fmt)4(H2O)2](ClO4)2, [Cu(fmt)3(NO3)2(H2O)], and [Cu2(fmt)4Br4], respectively. The obtained crystalline complexes and fmt were characterized by X-ray diffraction, thermal analyses, and IR spectroscopy. In the complexes, fmt acts as a monodentate ligand coordinated via the tetrazole ring N4 atom. [Cu(fmt)4(H2O)2](ClO4)2 comprises a mononuclear complex cation with an elongated CuN4O2 octahedron. [Cu(fmt)3(NO3)2(H2O)] presents a mononuclear complex, where the copper atom is in a heptacoordinate environment forming a considerably distorted pentagonal bipyramid. [Cu2(fmt)4Br4] presents a centrosymmetric dinuclear bromido-bridged complex with a square pyramidal environment of copper atoms.
In the title coordination polymer, {[Cu2Cl4(C20H16N10)]CH3CN}(n), the Cu-II atom is five-coordinated by two N atoms from the L ligand (where L is bis{[2-pyridyl(1H-tetrazol-5yl)]-1-ylmethyl}benzene) and three chloride ions to form a square-pyramidal geometry. The L ligands bridge adjacent Cu-II dinuclear units, forming a one-dimensional chain.
Since the diverse range of properties ascribed to ionic- and coordination compounds containing one-dimensional halide-bridged polymers of metal cations is controlled by their varied but unique one-dimensional structural characteristics, comprehension of the factors controlling connectivity and conformation will ultimately enable the inclusion of specific structural characteristics in the design of such materials. In this review, structures of one-dimensional halide-bridged polymers of alkali-, alkaline earth, transition-, post-transition metals and metalloids, with no restriction on oxidation state, with neutral coordinated- or cationic mono-heterocyclic type donor ligands or cations are reviewed. The work is prearranged topologically, firstly according to the coordination geometries around the metal centres and then according to connectivity. Structural trends between related systems are identified and interpreted by correlating chemical composition, connectivity and conformation, with specific focus on the role of hydrogen bonding interactions. A brief overview of properties and possible applications of these compounds, with slight relaxation of boundary conditions, is given.
We developed a new route for synthesis of Cr-based porous coordination polymers (PCPs) with azole ligands and characterized the unique open structures by single-crystal X-ray studies and other spectroscopy techniques. Chromium-based PCPs have been prepared from azolate ligands 3,5-dimethyl-1H-pyrazole-4-carboxylic acid (H2dmcpz) and 1,4-di(1H-tetrazole-5yl)benzene (H2BDT) by solvothermal reactions under an Ar atmosphere. [Cr3O(Hdmcpz)6(DMF)3]⊃DMF (1⊃DMF) is a coordination compound that forms a hydrogen-bonded porous network. [Cr3O(HBDT)2(BDT)Cl3)]⊃DMF (2⊃DMF) possesses a new type of trinuclear chromium μ3-O unit cluster and the novel topology of a Cr-based PCP with 700 m(2) g(-1) of Brunauer-Emmett-Teller surface area. [Cr(BDT)(DEF)]⊃DEF (3⊃DEF) is structurally flexible and reactive to O2 molecules because of the unsaturated Cr(2+) centers. This is the first report of a Cr-based PCP/metal-organic framework with noncarboxylate ligands and characterization by single-crystal X-ray diffraction.
Reaction of tetrazole-1-acetic acid (1-Htza) with a Cu(II) salt in ionic liquids with different anions, [BMIM]X (BMIM = 1-butyl-3-methylimidazolium; X = Br−, BF4−, NTf2− (NTf2− = bis((trifluoromethyl)sulfonyl)amide)), afforded five Cu(II) coordination compounds, [Cu2(1-tza)4]Br·H3O·1/3H2O (1), [Cu2(1-tza)4]BF4·H3O·H2O (2), [Cu(μ2-Cl)(1-tza)(1-Htza)(H2O)]·0.5H2O (3), [CuCl(μ2-Cl)(1-Htza)2(H2O)]·H2O (4), and [CuCl2(1-Htza)2]·H2O (5). Single-crystal X-ray diffraction analyses reveal that 1–5 display various structures, and the 1-tza− ligand exhibits diverse coordination modes. Compounds 1 and 2 possess higher dimensional structures (a 2-D neutral Kagomé topology network for 1 and a 3-D lvt-type topology framework for 2) with fully deprotonated 1-tza− ligands. Compounds 3–5 display lower dimensional structures (1-D, 1-D and 0-D for 3, 4 and 5, respectively) with partly or fully protonated 1-Htza. The anions of ionic liquids have significant influences on the final molecular architectures, which arise from different water miscibility of ionic liquids.
The title compound, C2H6N5+·C6H2N3O7−, was prepared by the equimolar reaction of 5-amino-1-methyltetrazole with picric acid. In the salt, the N4 atom of the tetrazole ring is protonated. Cations and anions in (I) are linked together by a complex set of hydrogen bonds, forming polymeric chains extending along the a axis, with van der Waals interactions between the chains.
In the title compound, [Cu2Cl4(C6H10N8)2]n, the ligand has C2 symmetry, and the Cu and Cl atoms lie on a mirror plane. The coordination polyhedron of the Cu atom is a distorted square pyramid, with the basal positions occupied by two N atoms from two different ligands [Cu—N = 2.0407 (18) Å] and by the two Cl atoms [Cu—Cl = 2.2705 (8) and 2.2499 (9) Å], and the apical position occupied by a Cl atom [Cu—Cl = 2.8154 (9) Å] that belongs to the basal plane of a neighbouring Cu atom. The [CuCl2(C6H10N8)]2 units form infinite chains extending along the a axis via the Cl atoms. Intermolecular C—H⃛Cl contacts [C⃛Cl = 3.484 (2) Å] are also present in the chains. The chains are linked together by intermolecular C—H⃛N interactions [C⃛N = 3.314 (3) Å].
The crystal structure of the polymeric title complex, [CuBr2(C4H8N8)2]n, has been solved from X-ray powder data and refined with the Rietveld method using geometrical soft restraints. The Cu atom, lying on an inversion centre, has octahedral coordination, with two N atoms [Cu—N = 2.090 (13) Å] and two Br atoms [Cu—Br = 2.432 (4) Å] in the equatorial positions. The axial sites of the octahedron are occupied by two Br atoms, with Cu—Br distances of 3.101 (4) Å. Each Br atom is a bridge between neighbouring Cu atoms, which is responsible for formation of polymeric layers parallel to the bc plane, with only van der Waals interactions between them.
The methylation of a series
of 15 sodium 5-substituted tetrazolates using iodomethane in acetone/water (4 : 1) has been studied. The
reaction yields both 1- and 2-methyl products, and the ratio of these products
is discussed in terms of the nature of the 5-substituent. Electronic and steric
effects dominate the reaction pathway; both increased substituent electro negativity
and steric bulk lead to predominant methylation at N2. Sodium
5-ethoxycarbonyltetrazolate (3n) goes against this trend and an intermediate is
proposed where the incoming electrophile is associated with the ester carbonyl
group.
Graphical abstract
The coordination of pyridyl-tetrazole derivatives containing ester substituents, at either the N-1 or N-2 position of the tetrazole ring, with copper(II) chloride results in the formation of either 1:1 or 1:2 copper to ligand complexes, depending on the ligand. However, when the ester functionality is changed to a carboxylate group, the resulting complexation reactions yield metal-organic frameworks, which vary dramatically depending on reaction conditions. For example, in complex 4 shown, each copper(II) ion is in a distorted octahedral geometry and a key feature of the molecular structure is that one of the L3A ligand (O1/O2/N12/N22) behaves in both a bridging (using O2/N12/N22) and chelating (via N12/N22) fashion while the second L3A ligand (O3/O4/N32/N42) is only involved in binding through its carboxylate group.
The title compound, {[CuCl2(PhTz)2]·0.5PhTz}n (PhTz is 1-phenyltetrazole, C7H6N4), has a polymeric structure, with uncoordinated disordered PhTz molecules in the cavities. The coordination polyhedron of the Cu atom is a highly elongated octahedron. The equatorial positions are occupied by two Cl atoms [Cu—Cl = 2.2687 (9) and 2.2803 (7) Å] and two N atoms of the PhTz ligands [Cu—N = 2.0131 (19) and 2.0317 (18) Å]. The more distant axial positions are occupied by two Cl atoms [Cu—Cl = 3.0307 (12) and 2.8768 (11) Å] that lie in the equatorial planes of two neighbouring Cu octahedra. The [CuCl2(PhTz)2] units are linked by Cu—Cl bridges into infinite chains extending parallel to the a axis. The chains are linked into two-dimensional networks by intermolecular C—H⋯N interactions between the phenyl and tetrazole fragments, and by face-to-face π–π interactions between symmetry-related phenyl rings. These two-dimensional networks, which lie parallel to the ac plane, are connected by intermolecular π–π stacking interactions between phenyl rings, thus forming a three-dimensional network.
One of the distinct features of metal-tetrazolate complexes is the possibility of performing electrophilic additions onto the imine-type nitrogens of the coordinated five-membered ring. These reactions, in particular, provide a useful tool for varying the main structural and electronic properties of the starting tetrazolate complexes. In this paper, we demonstrate how the use of a simple protonation-deprotonation protocol enables us to reversibly change, to a significant extent, the light-emission output and performance of a series of Re(I)-tetrazolate-based phosphors of the general formulation fac-[Re(N(∧)N)(CO)3L], where N(∧)N denotes diimine-type ligands such as 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen) and L represents a series of different 5-aryl tetrazolates. Indeed, upon addition of triflic acid to these neutral Re(I) complexes, a consistent blue shift (Δλmax ca. 50 nm) of the emission maximum is observed and the protonated species also display increased quantum yield values (4-13 times greater than the starting compounds) and longer decay lifetimes. This alteration can be reversed to the initial condition by further treating the protonated Re(I) complex with a base such as triethylamine. Interestingly, the reversible modulation of luminescent features by the same protonation-deprotonation mechanism appears as a quite general characteristic of photoactive metal tetrazolate complexes, even for compounds in which the 2-pyridyl tetrazolate ligands coordinate the metal center with a bidentate mode, such as the corresponding Ir(III) cyclometalates [Ir(C(∧)N)2L] and the Ru(II) polypyridyl derivatives [Ru(bpy)2L](+). In these cases, the protonation of the starting materials leads to red-shifted and more intense emissions for the Ir(III) complexes, while almost complete quenching is observed in the case of the Ru(II) analogues.
1-Alkyl-5-R-tetrazoles, free of the corresponding 2-isomers, can be readily obtained in high yield from 5-R-tetrazoles via exhaustive alkylation of their readily available 2-tert-butyl derivatives followed by removal of the tert-butyl group from the 1(4)-alkyl-3(2)-tert-butyl-5-R-tetrazolium salts formed.
The crystal structure of the dichlorobis(1-allyltetrazole-N4)copper(II) complex was determined by X-ray diffraction analysis. The crystals are monoclinic, a=14.233(3), b=6.755(1), c=7.273(1) Å, β=104.63(3)°, Vcell=676.6(2), Å3, space group P21/c, Z=4, dcalc=1.741g/cm3, dmsd=1.69 g/cm3, CAD-4, λMoKα radiation, RF=0.0377 for 520 Fhkl>4σ(Fhkl) and 0.0560 for all 872 independent reflections. The structure is layered; the coordination polyhedron of copper is a square bipyramid, in which the equatorial positions are occupied by two chlorine atoms (Cu−Cl 2.27(2)–2.31(2) Å) and two N4 atoms of planar tetrazole ligands, whereas the axial positions are occupied by two chlorine atoms of the neighboring molecules of the complex (Cu−Cl 2.97(2)–3.01(2) Å). The sublattice of chlorine atoms is disordered in such a way that the [CuCl4/2]∞∞ layer is a superposition of two variants with weights 61(3) and 39(3)% and with similar geometrical characteristics: the equatorial chlorine atoms in variant A are replaced by the axial atoms in variant B and vice versa. The tetrazole ligand has the same position in both variants. In general, the crystal is a polytype with random alternation of A and B type blocks. It is shown that the compound is isostructural to the complex with 1-ethyltetrazole [Cu(ettz)2Cl2], in which only variant B is realized.
New ruthenium tetrazol-5-yl (Tz) complexes with 1,10 phenanthroline (phen) and 2,2 bipyridine (bpy) as auxiliary ligands have been synthesized and characterized. When bpy is replaced by phen in ruthenium tetrazole complexes, yellow electroluminescence emission changes to green electroluminescence emission.
Physicochemical and explosive properties of tetraamminebis(1-methyl-5-aminotetrazole-N3,N4) cobalt(III) perchlorate were studied. The possibility of using this compound as priming charge was demonstrated.
The basicities of series of 5-R-tetrazoles in aqueous solutions of sulfuric acid were studied by UV and PMR spectroscopy. The pKBH+ values of these compound correlate with the sp substituent constants. The transmission factor of the p-phenylene ring (p' = 0.23) was calculated from the ratio of the reaction constants for protonation of substituted 5-phenyltetrazoles and 5-R-tetrazoles. A linear dependence between the pKa values and the pKBH+ values of 5-substituted tetrazoles was established.
The title polymeric compound, [CuCl2(C5H10N4)2]n, is the first structurally characterized complex with a bulky 1-alkyltetrazole ligand. The coordination polyhedron of the Cu atom is an elongated octahedron. The equatorial positions of the octahedron are occupied by the two Cl atoms, with Cu—Cl distances of 2.2920 (8) and 2.2796 (9) Å, and by the two N-4 atoms of the tetrazole ligands, with Cu—N distances of 2.023 (2) and 2.039 (2) Å. Two symmetry-related Cl atoms occupy the axial positions, at distances of 2.8244 (8) and 3.0174 (8) Å from the Cu atom. The [CuCl2(C5H10N4)2] units form infinite chains extended along the b axis, linked together only by van der Waals interactions. The skeleton of each chain consists of Cu and Cl atoms.
The title compound, [CuCl2(C8H14N8O)], is the first structurally characterized molecular chelate complex of a binuclear N-substituted tetrazole. The Cu atom is five-coordinate, with an approximately square-pyramidal geometry. The equatorial positions of the pyramid are occupied by two Cl atoms and two N atoms from the ligand molecule; the O atom of the ligand lies in the axial position. Each complex is connected to four others via weak C—H⋯Cl and C—H⋯N interactions, forming sheets parallel to the (010) plane.
The crystallographic problem: The production, and the visibility in the published literature, of thermal ellipsoid plots for small-molecule crystallographic studies remains an important method for assessing the quality of reported results. Since the mid 1960s, the program ORTEP (Johnson, 1965) has been perhaps the most popular computer program for generating thermal ellipsoid drawings for publication. The recently released update of ORTEP-III (Johnson & Burnett, 1996) has some additional features over the earlier versions, but still relies on fixed-format input files. Many users will find this very inconvenient, and will prefer to obtain drawings directly from their crystallographic coordinate files. This new version of ORTEP-3 for Windows provides all the facilities of ORTEP-III, but with a modern Graphical User Interface (GUI). Method of solution: A Microsoft-Windows GUI has been added to ORTEP-III. All the facilities of ORTEP-III are retained, and a number of extra features have been added. The GUI is effectively an editor that writes ORTEP-III input files, but the user need not have any knowledge of the inner workings of ORTEP. The main features of this program are: (i) ORTEP-3 for Windows can directly read many of the common crystallographic ASCII file formats. Currently supported formats are SHELX (Sheldrick, 1993), GX (Mallinson & Muir, 1985), GIF (Hall, Allen & Brown, 1991), SPF (Spek, 1990), CRYSTALS (Watkin, Prout, Carruthers & Betteridge, 1996), CSD-XR and CSD-FDAT. In addition, ORTEP-3 for Windows will accept any legal ORTEP-III instruction file. (ii) Covalent radii for the first 94 elements are stored internally, and may be modified by the user. All bonds are calculated automatically, and any individual bonds may be selected for removal, or for a special representation. (iii) The graphical representations of thermal ellipsoids for any element or selected sets of atoms can be individually set. All the possible graphical representations of thermal ellipsoids in ORTEP-III are also available in ORTEP-3 for Windows. (iv) A mouse labelling routine is provided by the GUI. Any number of selected atoms may be labelled, and any available Windows font may be used for the labels. The font attributes, e.g. italic, bold, colour, point size etc. can also be selected via a standard Windows dialog box. (v) As well as HPGL and PostScript Graphics graphic metafiles, it is also possible to get high quality graphics output by printing directly to an attached printer. The screen display may be saved as BMP or PCX format metafiles, and may also be copied to the clip-board for subsequent use by other Windows programs, e.g. word processing or graphics processing programs. Colour is available for all these output modes. (vi) A simple text editor is provided, so that input files may be modified without leaving the program. (vii) Symmetry expansion of the asymmetric unit to give complete connected fragments may be carried out automatically. (viii) Unit-cell packing diagrams are produced automatically. (ix) A number of options are provided to control the view direction. The molecular view may be rotated or translated by button commands from the tool bar, and views normal to crystallographic planes may also be obtained. Software environment and program specification: The program will read several common crystallographic file formats which hold information on the anisotropic displacement parameters. The operation of the program is carried out via standard self-explanatory MS-Windows menu items and dialog boxes. Hard-copy output is either by HPGL or Encapsulated PostScript metafiles, or by directly printing the graphics screen. Hardware environment: The program is implemented for IBM PC compatible computers running MS-Windows versions 3.1x, Windows 95 or Windows NT. At least a 486-66 machine is recommended with 8 Mbytes of RAM, and at least 5 Mbytes of disk space. Documentation and availability: The executable program, together with full documentation, is available free for academic users from http://www.chem. gla.ac.uk/̃louis/ortep3. Although the program is written in Fortran77, a large number of nonstandard FTN77 calls are used to create the GUI. For this reason, the source code is not available.
In the title compound, [CuCl2(C3H5N7)(2)], the coordination polyhedron of the Cu atom is an elongated square bipyramid with (1) over bar site symmetry. The equatorial positions are occupied by the two Cl atoms with Cu-Cl distances of 2.288 (1) Angstrom and two azidoethyltetrazole ligands with Cu-N distances of 1.999 (2) Angstrom. Two Cl atoms in axial positions are 2.956 (1) Angstrom distant from the Cu atom. The Cl atoms play the role of nonsymmetrical bridges responsible for formation of layers parallel to the bc plane.
Two new coordination complexes, Cu(datz)Cl2 and Cu(datz)2Cl2, where datz is 1,5-diaminotetrazole, have been obtained by the reaction of copper(II) chloride with datz. For one of them, Cu(datz)2Cl2, the crystal structure, magnetic susceptibility and thermal properties are reported. For the other compound only spectroscopic and thermal properties are presented. In Cu(datz)2Cl2 the Cu atoms were found to be octahedrally coordinated. Equatorial positions are occupied by two chloride anions and two tetrazole ligands via their N4 donor atoms. Surprisingly, the amino groups at the N1 atom of the tetrazole ring of nearby molecules are in axial positions. Each copper atom is linked with four others through the datz molecules to form 2D polymeric networks parallel to the yz plane. Magnetic properties of Cu(datz)2Cl2 and the data of quantum-chemical calculations of molecular electrostatic potential and energies of hydronation of nitrogen atoms for datz using MP2/6-31G* and B3LYP/6-31G* levels of theory are in agreement with the structural data obtained.
The current great interest in preparing functional metal-organic materials is inevitably associated with tremendous research efforts dedicated to the design and synthesis of new families of sophisticated multi-nucleating ligands. In this context, the N-donor triazole and tetrazole rings represent two categories of ligands that are increasingly used, most likely as the result of the recent dramatic development of “click chemistry” and Zeolitic Imidazolate Frameworks (ZIFs). Thus, azole-based complexes have found numerous applications in coordination chemistry.In the present review, we focus on the utilization of 1,2,3-triazole, 1,2,4-triazole and tetrazole ligands to create coordination polymers, metal complexes and spin-crossover compounds, reported to the end of 2009. In the first instance, we present a compendium of all the relevant ligands that have been employed to generate coordination polymers and Metal-Organic Frameworks (MOFs). Due to the huge amount of reported MOFs and coordination polymers bearing these azole rings, three representative examples for each category (therefore nine in total) are described in detail. The second section is devoted to the use of the bridging abilities of these azole ligands to prepare metal complexes (containing at least two metal centers). Given the large number and the great structural diversity of the polynuclear compounds found in the literature, these have been grouped according to their nuclearity. Finally, in the last section, the triazole- and tetrazole-containing coordination compounds exhibiting spin-crossover properties are presented.
In the title compound, [CUCl2(C3H6N4)(2)], the tetrazole ligand is coordinated terminally by the N4 ring atom. The coordination polyhedron of the Cu atom takes the form of an elongated square bipyramid with 1 site symmetry. The equatorial positions are occupied by two Cl atoms [Cu-Cl 2.290(1) Angstrom] and two ethyltetrazole ligands [Cu-N 1.990(4) Angstrom]. In addition, there are two Cl atoms in axial positions [Cu-Cl 2.993(1) Angstrom]. Hence, the Cl atoms play the role of non-symmetrical bridges and connect the molecules into infinite layers located in the yz plane.
The title compound, [CuCl2(C5H11N5)], is the first structurally characterized molecular chelate complex involving an α-aminoalkyltetrazole. There are two complex molecules in the asymmetric unit. The ligand molecules are bidentate. Both Cu atoms reveal rather distorted square-planar coordinations. The complex molecules are linked together by van der Waals interactions only.
Here, we used circular dichroism (CD) and fluorescence microscopy (FM) to examine the interactions of a series of antitumor-active tetrazolato-bridged dinuclear platinum(II) complexes, [{cis-Pt(NH3)2}2(μ-OH)(μ-5-R-tetrazolato-N2,N3)](n+) (R=CH3 (1), C6H5 (2), CH2COOCH2CH3 (3), CH2COO(-) (4), n=2 (1-3) or 1 (4)), which are derivatives of [{cis-Pt(NH3)2}2(μ-OH)(μ-tetrazolato-N2,N3)](2+) (5-H-Y), with DNA to elucidate the influence of these interactions on the secondary or higher-order structure of DNA and reveal the mechanism of action. The CD study showed that three derivatives, 1-3, with a double-positive charge altered the secondary structures of calf thymus DNA but that 4, the only complex with a single positive charge, induced almost no change, implying that the B- to C-form conformational change is influenced by ionic attraction. Unexpectedly, single-molecule observations with FM revealed that 4 changed the higher-order structure of T4 DNA into the compact-globule state most efficiently, at the lowest concentration, which was nearly equal to that of 5-H-Y. These contradictory results suggest that secondary structural changes are not necessarily linked to higher-order ones, and that the non-coordinative interaction could be divided into two distinct interactions: (1) ionic attraction and (2) hydrogen bonding and/or van der Waals contact. The relationship between diffusion-controlled non-coordinative DNA interactions and cytotoxicities is also discussed.
The reaction of 2-(2H-tetrazol-5-yl)pyridine (L1) with 1,6-dibromohexane results in formation of the isomers
2-(600-bromohexyl)-(1-tetrazol-5-yl)pyridine (L2) and 2-(600-bromohexyl)-(2-tetrazol-5-yl)pyridine
(L3). Coordination reactions of L2 and L3 with CuCl2�2H2O, Co(SCN)2 and Fe(ClO4)2�H2O yielded the
strongly coloured solids [Cu(II)(L2)Cl2]2 (1), [Cu(II)(L3)Cl2]2 (2), [Co(II)(L2)2(NCS)2] (3), [Co(II)(L3)2(NCS)2]
(4), [Fe(II)(L2)2(H2O)2](ClO4)2 (5) and [Fe(II)(L3)2(H2O)2](ClO4)2 (6), containing high-spin metal centres
for the Co(II) and Fe(II) compounds. X-ray crystal structures were obtained for complexes 1–5. In each
complex, ligands L2 and L3 coordinate to the metal centre through the pyridyl N atom and the 1-N site
of the tetrazole ring, and the pyridyl–tetrazole ligand remains planar in all cases except 3. Complexes 1
and 2 comprise a central Cu2Cl2 dimeric core with Cu(II) in an essentially square-pyramidal coordination
environment. Complexes 3 and 4 contain Co(II) in a distorted octahedral coordination environment. In 3,
the pyridyl and tetrazole rings of L2 are twisted with respect to each other and the complex adopts a
puckered conformation in its equatorial plane. Complex 5 contains water molecules coordinated to Fe(II)
in the axial sites, which form hydrogen bonds to the perchlorate counter anions.
5-(Tetrazol-1-yl)-2H-tetrazole (1), or 1,5'-bistetrazole, was synthesized by the cyclization of 5-amino-1H-tetrazole, sodium azide and triethyl orthoformate in glacial acetic acid. A derivative of 1, 2-methyl-5-(tetrazol-1-yl)tetrazole (2) can be obtained by this method starting from 5-amino-2-methyl-tetrazole. Furthermore, selected salts of 1 with nitrogen-rich and metal (alkali and transition metal) cations, including hydroxylammonium (4), triaminoguanidinium (5), copper(I) (8) and silver (9), as well as copper(II) complexes of both 1 and 2 were prepared. An intensive characterization of the compounds is given, including vibrational (IR, Raman) and multinuclear NMR spectroscopy, mass spectrometry, DSC and single-crystal X-ray diffraction. Their sensitivities towards physical stimuli (impact, friction, electrostatic) were determined according to Bundesamt für Materialforschung (BAM) standard methods. Energetic performance (detonation velocity, pressure, etc.) parameters were calculated with the EXPLO5 program, based on predicted heats of formation derived from enthalpies computed at the CBS-4M level of theory and utilizing the atomization energy method. From the analytical and calculated data, their potential as energetic materials in different applications was evaluated and discussed.
We synthesised four tetrazolato-bridged dinuclear Pt(ii) complexes, [{cis-Pt(NH3)2}2(μ-OH)(μ-5-R-tetrazolato-N2,N3)](n+), where R is CH3 (), C6H5 (), CH2COOC2H5 (), or CH2COO(-) () and n = 2 () or 1 (). Their structures were characterised by (1)H, (13)C, and (195)Pt NMR spectroscopy, mass spectrometry, and elemental analysis, and the crystal structure of was determined by X-ray crystallography. The cytotoxicities of the complexes to human non-small-cell lung cancer (NSCLC) cell lines sensitive and resistant to cisplatin were assayed. Complex was more cytotoxic than cisplatin in both PC-9 and PC-14 NSCLC cell lines, and cross-resistance to in the cisplatin-resistant cells was largely circumvented. Complex was moderately cytotoxic, whereas and were only marginally cytotoxic. We also determined the growth inhibitory activities of and , as well as prototype azolato-bridged complexes [{cis-Pt(NH3)2}2(μ-OH)(μ-pyrazolato)](2+) (), [{cis-Pt(NH3)2}2(μ-OH)(μ-1,2,3-triazolato-N1,N2)](2+) (), [{cis-Pt(NH3)2}2(μ-OH)(μ-tetrazolato-N1,N2)](2+) (), and [{cis-Pt(NH3)2}2(μ-OH)(μ-tetrazolato-N2,N3)](2+) (), against a panel of 39 human cancer cell lines (JFCR39). The average 50% growth inhibition concentrations of the complexes against the JFCR39 cell lines ranged from 0.933 to 23.4 μM. The cytotoxicity fingerprints of the complexes based on the JFCR39 cytotoxicity data were similar to one another but completely different from the fingerprints of clinical platinum-based anticancer drugs. Complex exhibited marked antitumor efficiency when tested in vivo on xenografts of PANC-1 pancreatic cancer in nude mice. The high potency of confirmed that the tetrazolato-bridged structure exhibits high in vivo antitumor efficacy.
The linear quadridentate N2S2 donor ligand 1,7-bis(N-methylbenzimidazol-2′-yl)-2,6-dithiaheptane (bmdhp) forms mono- and di-hydrate 1 : 1 copper(II) complexes which are significantly more stable toward autoreduction than those of the non-methylated analogue. The deep green monohydrate of the perchlorate salt crystallises as the mononuclear aqua-complex, [Cu(bmdhp)(OH2)][ClO4]2, in the monoclinic space group P21/n, with Z= 4, a= 18.459(3), b= 10.362(2), c= 16.365(3)Å, and β= 117.14(1)°. The structure was solved and refined by standard Patterson, Fourier, and least-squares techniques to R= 0.047 and R′= 0.075 for 3 343 independent reflections with l > 2σ(l). The compound consists of [Cu(bmdhp)(OH2)]2+ ions and ClO4– counter ions. The co-ordination around copper is intermediate between trigonal bipyramidal and square pyramidal, with Cu–N distances of 1.950(4) and 1.997(4)Å, Cu–O(water) 2.225(4)Å, and Cu–S 2.328(1) and 2.337(1)Å. In the solid state, the perchlorate dihydrate's co-ordination sphere may be a topoisomer of the monohydrate's. A new angular structural parameter, τ, is defined and proposed as an index of trigonality, as a general descriptor of five-co-ordinate centric molecules. By this criterion, the irregular co-ordination geometry of [Cu(bmdhp)(OH2)]2+ in the solid state is described as being 48% along the pathway of distortion from square pyramidal toward trigonal bipyramidal. In the electronic spectrum of the complex, assignment is made of the S(thioether)→ Cu charge-transfer bands by comparison with those of the colourless complex Zn(bmdhp)(OH)(ClO4). E.s.r. and ligand-field spectra show that the copper(II) compounds adopt a tetragonal structure in donor solvents.
A variation of Gaussian-3 (G3) theory is presented in which the geometries and zero-point energies are obtained from B3LYP density functional theory [B3LYP/6-31G(d)] instead of geometries from second-order perturbation theory [MP2(FU)/6-31G(d)] and zero-point energies from Hartree–Fock theory [HF/6-31G(d)]. This variation, referred to as G3//B3LYP, is assessed on 299 energies (enthalpies of formation, ionization potentials, electron affinities, proton affinities) from the G2/97 test set [J. Chem. Phys. 109, 42 (1998)]. The G3//B3LYP average absolute deviation from experiment for the 299 energies is 0.99 kcal/mol compared to 1.01 kcal/mol for G3 theory. Generally, the results from the two methods are similar, with some exceptions. G3//B3LYP theory gives significantly improved results for several cases for which MP2 theory is deficient for optimized geometries, such as CN and O2+. However, G3//B3LYP does poorly for ionization potentials that involve a Jahn–Teller distortion in the cation (CH4+, BF3+, BCl3+) because of the B3LYP/6-31G(d) geometries. The G3(MP2) method is also modified to use B3LYP/6-31G(d) geometries and zero-point energies. This variation, referred to as G3(MP2)//B3LYP, has an average absolute deviation of 1.25 kcal/mol compared to 1.30 kcal/mol for G3(MP2) theory. Thus, use of density functional geometries and zero-point energies in G3 and G3(MP2) theories is a useful alternative to MP2 geometries and HF zero-point energies. © 1999 American Institute of Physics.