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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.

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Chapter
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.
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Article
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
Article
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].
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
Two series of tetrazole-containing platinum(II) and palladium(II) chlorido complexes, trans-[ML(2)Cl(2)] (M=Pt, Pd) and cis-[PtL(2)Cl(2)]·nH(2)O (n=0, 1), where L is 1- or 2-substituted 5-aminotetrazole, have been synthesized and thoroughly characterized. Configuration of platinum(II) complexes obtained from the reaction of 5-aminotetrazoles with K(2)PtCl(4) has been found to vary depending on the nature of tetrazole derivatives and reaction conditions. According to in vitro cytotoxic evaluation, only platinum complexes display noticeable antiproliferative effect, and their cytotoxicity depends strongly on their geometry and hydrophobicity of the carrier ligands. The most promising complexes are cis-[Pt(1-apt)(2)Cl(2)]·H(2)O and cis-[Pt(2-abt)(2)Cl(2)]·H(2)O, where 1-apt is 5-amino-1-phenyltetrazole and 2-abt is 5-amino-2-tert-butyltetrazole. In comparison with cisplatin, they show comparable cytotoxic potency against cisplatin-sensitive human cancer cell lines, cis-[Pt(2-abt)(2)Cl(2)]·H(2)O performing substantially higher activity against cisplatin-resistant cell lines. Cell cycle studies in H1299 cell line indicated that cis-[Pt(2-abt)(2)Cl(2)]·H(2)O induced apoptosis launched from G2 accumulations. The DNA interaction with cis-[Pt(1-apt)(2)Cl(2)]·H(2)O was followed by UV spectroscopy, circular dichroism, hydrodynamic and electrophoretic mobility studies. Both cis-[Pt(1-apt)(2)Cl(2)]·H(2)O and cis-[Pt(2-abt)(2)Cl(2)]·H(2)O complexes appeared to be significantly less toxic than cisplatin in mice, while only compound cis-[Pt(1-apt)(2)Cl(2)]·H(2)O displayed noticeable efficacy in vivo.