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Abstract: Density functional theory calculations have been carried out to study the process of NO adsorption on neutral, anionic and cationic Ag8 clusters. Three cluster types have been considered in our study: D2d and Td structures are the most stable isomers in gas phase and C1 structure, which has the geometry of the most stable isomer adsorbed on rutile TiO2 (110) surface. Adsorption energies, N–O bond lengths and corresponding N–O vibration frequencies have been calculated for all structures. It has been shown that in the case of NO interaction with D2d structure the corresponding adsorption energies grow in the following order: E ads(cation)< E ads(neutral)< E ads(anion). The same regularity has been observed for NO interaction with silver tetramers in our previous study. For the Td structure the highest adsorption energy is also observed in case of anionic complex. However, for C1 structure other dependence has been observed: E ads(anion)< E ads(cation)< E ads(neutral). The adsorption of NO on neutral Ag8 cluster (C1 structure) is characterized by the largest N–O bond elongation which should be useful for NO fragmentation process. [ABSTRACT FROM AUTHOR]

Abstract: The formation enthalpies of tautomeric forms of 1,2,3-triazole, 4(5)-nitro-1,2,3-triazole and isomeric N-alkyl-4(5)-nitro-1,2,3-triazoles (alkyl=methyl, ethyl, isopropyl and tert-butyl) have been calculated with the density functional theory B3LYP method by means of designed isolobal, isodesmic and isomerisation reactions. The experimental ideal-gas formation enthalpy of 2-methyl-4-nitro-1,2,3-triazole has been determined based on the formation enthalpy in the crystalline state and the sublimation enthalpy. The experimental value of formation enthalpy (228.7±3.5kJmol−1) is in good agreement with the one obtained from reaction enthalpy calculations (233.5kJmol−1). The relative Gibbs energies for tautomeric forms of 1,2,3-triazole and 4(5)-nitro-1,2,3-triazole and isomeric N-alkyl-4(5)-nitro-1,2,3-triazoles in aqueous solution have also been calculated using the Conductor polarized continuum model (CPCM). The results of the calculations have been discussed concerning the relative stability of the titled compounds. [Copyright &y& Elsevier]

Calculations of equilibrium geometry, vertical detachment energies (VDE) and transition energies (Te) from the electronic ground state to excited states of Cun- clusters (n=2–10) have been carried out within DFT model with the new functional developed recently [J. Mol. Struct. (Theochem) 664–665 (2003) 291]. The results of calculations have been compared with observed photoelectron spectra (PHES). The method provides a good agreement between calculations and experiment. For anionic Cu2–10- clusters, the difference between calculated and experimental values of VDE and Te for the most stable isomers does not exceed 0.21 eV. The assignment of previously unknown Cu6-, Cu8-, Cu9- and Cu10- structures has been made by both total energy calculations and comparison of experimental and calculated PHES. The electronic sructure, geometry and energetic characteristics of low-lying isomers have been studied. [Copyright &y& Elsevier]

A comparative analysis of bond lengths (re), vertical detachment energies (VDE), excitation energies of neutral clusters with geometry of anions (Te) and vertical ionization potentials of neutral clusters (IPv) calculated within density functional theory (DFT) using different functionals with both effective core potential (ECP) and all-electron basis sets for silver clusters Agn, n≤6, have been carried out. DFT methods provide a good agreement between calculated and experimental data of some characteristics. The accurate prediction of all characteristics simultaneously can be achieved with all-electron DZVP basis set only. A new functional has been developed. It provides results close to experimental data using the moderate basis set. For anionic clusters Ag2–10−, the difference between calculations with this functional and experimental values of VDE and Te for the most stable isomers does not exceed 0.1 eV. Based on both total energy calculations and comparison of experimental and calculated photoelectron spectra, the structural assignment of clusters Ag7−, Ag9− and Ag10− has been made. The electronic structure and geometrical characteristics of the low-lying isomers has been studied. [Copyright &y& Elsevier]

Abstract: The adsorption of Ag n (n =2,4,8) clusters on the partially reduced rutile (110) surface have been studied using DFT slab calculations. The geometry and electronic structure of silver clusters adsorbed near the oxygen vacancy as well as binding mechanism have been investigated. It has been found that the binding occurs through two types of interaction. Firstly, it is the interaction between cluster’s HOMO and surface eigenstates located on hollow-Ti atoms and, secondly, the overlap of MOs of the cluster with bridging oxygen atoms. The first type leads to charge transfer from the adsorbed cluster to the surface, therefore silver particles become positively charged upon adsorption. The second type leads to the deformation of adsorbed silver cluster, thereby increasing the overlap. The interaction between molecular orbitals of the cluster and orbitals of atoms lying at the vacancy is unlikely. It has been shown that the adsorption energy of Ag n clusters on stoichiometric surface are higher than those for reduced surface. Thus, the adsorption of silver clusters occurs preferably on stoichiometric surface far from oxygen vacancies. [Copyright &y& Elsevier]

Abstract: The CH acidity of all possible N-methyl substituted nitrotriazoles as well as of some 4-substituted 1,2,3-triazoles and N-alkyl-4-nitro-1,2,3-triazoles in the gas phase and in THF and DMSO solution has been calculated with the density functional theory B3LYP method. Electronic effects of substituents on the CH acidity of 4-substituted 1,2,3-triazoles have been examined using linear free energy relationship (LFER) methodology. In order to investigate the relation between the CH acidity of the heterocycles and their ability to undergo electrophilic substitution involving C–H bond cleavage, we have studied the reaction of isomeric N-alkyl-4-nitro-1,2,3-triazoles (alkyl=methyl, ethyl, isopropyl and tert-butyl) with HgBr2 in alkali solution. It was found that 1-isomers undergo mercuration readily, while mercuration of 2-substituted compounds do not occur under the same conditions, which is in agreement with the results of DFT calculations of the CH acidity of the compounds, showing that 2-isomers have considerably lower CH acidity than 1-isomers. [Copyright &y& Elsevier]

Abstract: Titanium dioxide with silver nanoparticles deposited on the surface is known to exhibit higher photocatalytic activity than the uncovered TiO2. A study of the electronic structure of such systems is necessary to understand this effect. A quantum chemical study of silver tetramers adsorption on stoichiometric rutile (110) surface has been carried out using periodic DFT calculations. A number of adsorption positions, which correspond to two basic adsorption sites on TiO2 (i.e. bridging oxygen rows and hollow sites) have been considered. The hollow sites turned out to be preferable for Ag4 adsorption. The population analysis has been performed to study mechanism of interaction between Ag4 and TiO2 surface. The binding has been shown to occur mainly through the interaction between cluster HOMO and rutile conduction band eigenstates. A significant overlap between Ag4 HOMO and titanium orbitals has been found in the case of hollow site adsorption, in contrast to adsorption over bridging oxygen rows, where there is only weak binding towards oxygen atoms. The adsorbed cluster has been found to have a significant positive charge, which is a result of a charge transfer into conduction band. [Copyright &y& Elsevier]

Abstract: The CH acidity in gas phase and in THF and DMSO solution of 12 N-alkyl substituted azoles have been calculated with the density functional theory B3LYP method. The computed pK a values of azoles in THF solution and positions of deprotonation agree with experimentally found. The calculation results enabled us to explain a great difference in reactivity of 2-alkyltetrazoles comparing with 1-alkyltetrazoles in processes involving C–H bond cleavage (mercuration, iodination, aminomethylation). For studied compounds and corresponding anions three geometric aromaticity indices were calculated and π-electron delocalization was studied by means of natural bond orbital analysis. The results obtained were used to explain positions of deprotonation of azoles’ molecules. [Copyright &y& Elsevier]

Abstract: Based on both total energy calculations and comparison of experimental and calculated characteristics of photoelectron spectra (PHES), the structural assignment of clusters and has been made using DFT model with recently developed S2LYP functional. The calculated characteristics of PHES for the assigned structures are in excellent agreement with the experimental ones. The electronic structure, geometry and energetic characteristics of low-lying isomers have also been studied. The calculated geometrical parameters of and clusters as well as the geometries of earlier established clusters have been compared with the geometrical characteristics of anionic sodium clusters. The structures of anionic silver and sodium clusters have been found to be very similar. The difference has been observed only for . Based on similarity of the geometries of silver and sodium clusters as well as on the comparison of calculated and experimental characteristics of PHES, the geometry of cluster has been assigned. [Copyright &y& Elsevier]

Despite the arrangement of donor centers suggesting chelation, 2-(1 H -tetrazol-1-yl)thiazole is coordinated by only N4 atom of the tetrazole cycle in copper(II) and cobalt(II) complexes. Under interaction with copper(II) chloride and ethanol it also undergoes tetrazole ring transformation leading to ethyl thiazol-2-ylcarbamimidate complex. 2-(1 H -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) 2 Cl 2 ] n (1) and [Cu 2 (ethc) 2 Cl 4 ]·2H 2 O (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 [Cu 2 (tth) 4 Cl 4 ] (3) were isolated. Ligand tth was found to react with copper(II) tetrafluoroborate and cobalt(II) chloride giving [Cu(tth) 2 (H 2 O) 4 ](BF 4) 2 (4) and [Co(tth) 2 Cl 2 (H 2 O) 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. [ABSTRACT FROM AUTHOR]

Graphical abstract A strong effect of C5-substituent on coordination modes of 1-methyl-5-R-tetrazoles and structural motifs of their copper(II) chloride complexes was observed. Abstract A series of cupric chloride complexes with 1-methyl-5-R-tetrazole ligands, where R = NH 2 , t -Bu, Ph, MeS, CH CH 2 , MeSO 2 , were synthesized by interaction of CuCl 2 ·2H 2 O with the above ligands LNH 2 , LtBu, LPh, LMeS, LVin, and LMeSO 2 , respectively. The obtained complexes [Cu(LNH 2 ) 3 Cl 2 ]·H 2 O (1), [Cu(LtBu) 2 Cl 2 ] (2), [Cu(LPh) 2 Cl 2 ] (3), [Cu(LMeS) 2 Cl 2 ] (4), [Cu(LVin)Cl 2 ] n (5), and [Cu(LMeSO 2 )(H 2 O)Cl 2 ] n (6) were characterized by single crystal X-ray analysis. The effect of C5-substituent on coordination modes of tetrazole ligands and structural motifs of complexes was observed. Complexes 1 – 4 are mononuclear, with the tetrazole ring N4 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 N3,N4-bridge). In 6 , being also 1D coordination polymer, coordination chains are composed of alternating Cu(LMeSO 2 ) 2 and Cu(H 2 O) 2 fragments linked by double chlorido bridges. Ligand LMeSO 2 shows N3 coordination, being rare among 1,5-disubstituted tetrazoles. The influence of the nature of C5 substituents on coordination features of the obtained complexes is discussed by using quantum-chemical calculations of the electronic structure and basicity of the ligands. [ABSTRACT FROM AUTHOR]

Complexes [Cu 2 L 2 Cl 4 ], [NiL 2 Cl 2 ], [PdLCl 2 ], and [PtLCl 2 ], where L is a novel ligand from the series of 2-subsituted 5-(α-aminoalkyl)tetrazoles, namely 5-( N , N -dimethylaminomethyl)-2- tert -butyltetrazole, have been synthesized and characterized by IR spectroscopy, thermal analysis and single crystal X-ray analysis. The complexes reported show different coordination geometries of the metals, viz. octahedral for Ni, square pyramidal for Cu, and square planar for Pt and Pd complexes. At the same time, the ligand L demonstrates the same coordination mode in all the complexes. It acts as a chelating ligand coordinated to the metal via two nitrogen atoms, namely the tetrazole ring N 4 and the dimethylamino N atoms. Complex [PtLCl 2 ] was found to have promising antiproliferative activity against human cervical carcinoma cells, with IC 50 value being average between those of cisplatin and carboplatin. The temperature-dependent magnetic susceptibility measurements of complex [Cu 2 L 2 Cl 4 ] revealed that the copper(II) ions were weakly antiferromagnetically coupled showing a coupling constant J of −2 cm −1 . [ABSTRACT FROM AUTHOR]

A new method for Huisgen [3+2] cycloaddition synthesis of 1,4- and 1,4,5-substituted-1 H -1,2,3-triazoles was reported. The reaction was catalyzed by the product of thermolysis of copper (II) poly-5-vinyltetrazolate. Heterogeneous catalyst includes copper nanoparticles which supported on polymeric matrix. It presents recovered and recycled catalyst and the catalyzed reaction proceeds in aerobic conditions at room temperature in aqueous media. [ABSTRACT FROM AUTHOR]

A series of methoxy- and fluoro-pyridines have been deprotometalated in tetrahydrofuran at room temperature by using a mixed lithium–zinc combination obtained from ZnCl 2 ·TMEDA (TMEDA= N , N , N ′, N ′-tetramethylethylenediamine) and LiTMP (TMP=2,2,6,6-tetramethylpiperidino) in a 1:3 ratio, and the metalated species intercepted by iodine. Efficient functionalization at the 3 position was observed from 4-methoxy, 2-methoxy, 2,6-dimethoxy, 2-fluoro and 2,6-difluoropyridine, and at the 4 position from 3-methoxy and 2,3-dimethoxypyridine. Interestingly, clean dideprotonation was noted from 3-fluoropyridine (at C2 and C4) and 2,6-difluoropyridine (at C3 and C5). The obtained regioselectivities have been discussed in light of the CH acidities of the substrates, determined both in the gas phase (DFT B3LYP and G3MP2B3 levels) and in THF solution. In the case of methoxypyridines, the p K a values have also been calculated for complexes with LiCl and LiTMP. [ABSTRACT FROM AUTHOR]

Substituted azafluorenones were synthesized from dihalogeno diaryl ketones under palladium catalysis by combining, in auto-tandem processes, Suzuki coupling and intramolecular arylation reactions. Different dihalogenated diaryl ketones, prepared by sequential deprotocupration-aroylation, were identified as suitable substrates to this purpose. Conditions were identified to allow successful syntheses of several 6-/7-arylated 4-azafluorenones, 1-substituted 4-azafluorenones, 2-phenyl-3-azafluorenone, and 4-phenyl-3-azafluorenone from 3-(bromobenzoyl)-2-chloropyridines, 3-benzoyl-4-bromo-2-chloropyridines, 4-benzoyl-2,5-dichloropyridine, and 4-benzoyl-2,3-dichloropyridine, respectively. Some of the synthesized compounds exhibit interesting biological properties. [ABSTRACT FROM AUTHOR]

1-Aryl- and 2-aryl-1,2,3-triazoles were synthesized by N -arylation of the corresponding azoles using aryl iodides. The deprotometalations of 1-phenyl-1,2,3-triazole and -1,2,4-triazole were performed using a 2,2,6,6-tetramethylpiperidino-based mixed lithium–zinc combination and occurred at the most acidic site, affording by iodolysis the 5-substituted derivatives. Dideprotonation was noted from 1-(2-thienyl)-1,2,4-triazole by increasing the amount of base. From 2-phenyl-1,2,3-triazoles, and in particular from 2-(4-trifluoromethoxy)phenyl-1,2,3-triazole, reactions at the 4 position of the triazolyl, but also ortho to the triazolyl on the phenyl group, were observed. The results were analyzed with the help of the CH acidities of the substrates, determined in THF solution using the DFT B3LYP method. 4-Iodo-2-phenyl-1,2,3-triazole and 4-iodo-2-(2-iodophenyl)-1,2,3-triazole were next involved in Suzuki coupling reactions to furnish the corresponding 4-arylated and 4,2′-diarylated derivatives. When evaluated for biological activities, the latter (which are resveratrol analogues) showed moderate antibacterial activity and promising antiproliferative effect against MDA-MB-231 cell line. [ABSTRACT FROM AUTHOR]

Abstract: Two series of tetrazole-containing platinum(II) and palladium(II) chlorido complexes, trans-[ML2Cl2] (M=Pt, Pd) and cis-[PtL2Cl2]·nH2O (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 K2PtCl4 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)2Cl2]·H2O and cis-[Pt(2-abt)2Cl2]·H2O, 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)2Cl2]·H2O performing substantially higher activity against cisplatin-resistant cell lines. Cell cycle studies in H1299 cell line indicated that cis-[Pt(2-abt)2Cl2]·H2O induced apoptosis launched from G2 accumulations. The DNA interaction with cis-[Pt(1-apt)2Cl2]·H2O was followed by UV spectroscopy, circular dichroism, hydrodynamic and electrophoretic mobility studies. Both cis-[Pt(1-apt)2Cl2]·H2O and cis-[Pt(2-abt)2Cl2]·H2O complexes appeared to be significantly less toxic than cisplatin in mice, while only compound cis-[Pt(1-apt)2Cl2]·H2O displayed noticeable efficacy in vivo. [Copyright &y& Elsevier]

Abstract: The behavior of amino- and mercapto-1,2,4-triazoles in a t-BuOH–HClO4 system has been examined. Under the investigated conditions monoalkylation of 3-amino-1,2,4-triazole proceeds at the endocyclic N1 atoms whereas 1,2,4-triazole-3-thiol undergoes S-tert-butylation. Exhaustive alkylation of the above mentioned triazoles results in di-tert-butyl substituted derivatives, which give 1,3-disubstituted triazoles under the action of base. 4-Amino-1,2,4-triazole undergoes alkylation on the amino group as well as on the endocyclic N1 atom giving a 1,4-disubstituted triazolium salt. An X-ray diffraction investigation of 5-tert-butylsulfanyl-1,2,4-triazole, 1-tert-butyl-3-tert-butylamino-1,2,4-triazol-4-ium, 1-tert-butyl-3-tert-butylsulfanyl-1,2,4-triazol-4-ium, and 1-tert-butyl-4-tert-butylamino-1,2,4-triazolium perchlorates was carried out. [Copyright &y& Elsevier]

Abstract: Complexes ML1 2 and ML2 2, with M=FeII, CoII, NiII, and 1,3-bis(2-R-tetrazol-5-yl)triazenide ligands L1 (R=Me) and L2 (R= tBu), have been synthesized by the reaction of corresponding 1,3-bis(2-R-tetrazol-5-yl)triazenes with metal(II) salts in basic media and characterized by IR, UV–Vis spectroscopy, thermal and X-ray diffraction analyses. Both 1,3-bis(2-R-tetrazol-5-yl)triazenes were found to deprotonate on coordination and act as tridentate chelating ligands forming distorted MN6 octahedra around metal(II) cations. [ABSTRACT FROM AUTHOR]

Abstract: Complexes CuL3Cl2, PdL2Cl2 and PtL2Cl2, where L is a novel ligand from the series of 2-substituted 5-aminotetrazoles, namely 5-amino-2-tert-butyltetrazole (1), have been synthesized by the reaction of metal(II) chlorides with 1 and characterized by IR spectroscopy, thermal and X-ray analyses. The crystallographic structural analysis of these complexes revealed that 1 acts as a monodentate ligand coordinated to the metal via endocyclic N4 atom. Platinum complex demonstrates promising cytotoxicity against human cervical carcinoma cells with IC50 value average between those of cisplatin and carboplatin. [Copyright &y& Elsevier]

Abstract: Stable and nearly monodispersed gold nanoparticles with sizes of 2.8–4.7nm are easily prepared by the reduction of tetrachloroaurate salts in a toluene-water system in the presence of 1-R-5-thiotetrazoles (R=Et, t-Bu, 1-adamatyl). The prepared gold nanoparticles were characterized by TEM, XRD, UV–Vis, FTIR and TGA. [Copyright &y& Elsevier]

Abstract: A new method for the synthesis of 1,3,5-trisubstituted aminotetrazolium salts based on alkylation of 1- and 5-aminotetrazoles with the t-BuOH–HClO4 system is presented. Depending on the structure of the tetrazole substrate and reaction conditions, alkylation proceeds at the endocyclic nitrogen atoms as well as at the 1- and 5-amino groups giving mono-, di-, and tri-tert-butyl substituted tetrazolium salts. An X-ray diffraction investigation of 3-tert-butyl-1,5-bis(tert-butylamino)tetrazolium perchlorate and 5-amino-1,3-di-tert-butyltetrazolium chloride was carried out. [Copyright &y& Elsevier]

Abstract: Based on both total energy calculations and comparison of experimental and calculated characteristics of photoelectron spectra (PHES), the structural assignment of , and clusters has been made using DFT model with previously developed S2LYP functional. In case of cluster our decisions were also based on similarity of the geometries of copper and sodium clusters. The calculated characteristics of PHES for all the assigned structures are in excellent agreement with the experimental ones. The assigned geometries of and have been compared with those of recently established structures of silver clusters, which turned out to be very similar. In the meantime, the structure of the most stable cluster is significantly distorted in comparison with the structure of cluster. [Copyright &y& Elsevier]

A new representative of copper(II) halide complexes with 1,5-disubstituted tetrazoles, a single chain chlorido bridged coordination polymer, shows antiferromagnetic coupling. The same type of magnetic interactions was found in other polymeric chain complexes having double chlorido bridges and N3,N4-bridges between the copper atoms. • 5-(N,N-dimethylaminomethyl)-1-(pyridin-2-yl)tetrazole acts as a chelating ligand. • New cupric chloride complex with 1,5-disubstituted tetrazole was characterized. • Mono and dichlorido-bridged copper 1D coordination polymers showed AFM coupling. The complex [Cu(5-(N,N-dimethylaminomethyl)-1-(pyridin-2-yl)tetrazole)Cl 2 ] 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)Cl 2 ] n (2) and [Cu 2 (1-methyl-5-methylsulfonyltetrazole) 2 (H 2 O) 2 Cl 4 ] 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(H 2 O) 2 fragments. [ABSTRACT FROM AUTHOR]

Under the action of cupric chloride, a novel bistetrazole shows the N4,N4′-bridging coordination mode, giving 1D coordination polymers with Cu 2 Cl 4 units. In solution these complexes transform into a 2D coordination polymer, which includes trinuclear Cu 3 Cl 6 units linked by bistetrazole ligands showing a tridentate N3,N4,N4′-bridging coordination. • A novel bistetrazole ligand was prepared by a regioselective procedure. • The bistetrazole shows bridging coordination, generating 1D and 2D coordination polymers. • In coordination polymers Cu 2 Cl 4 and Cu 3 Cl 6 units are linked by bistetrazole. • Antiferromagnetic coupling between copper atoms in the Cu 3 Cl 6 units was observed. 1,3-Bis(1-methyl-1 H -tetrazol-5-yl)propane (bmtp) was prepared by a procedure including regioselective tert -butylation of 1,3-bis(1 H -tetrazol-5-yl)propane and exhaustive methylation of the obtained 1,3-bis(2- tert -butyl-1 H -tetrazol-5-yl)propane, followed by removal of the tert -butyl group from the tetrazolium salt under acidic conditions. The ligand bmtp reacts with CuCl 2 ·2H 2 O in ethanol to give the complexes [Cu 3 (bmtp) 2 Cl 6 (H 2 O) 2 ] n and [Cu(bmtp)Cl 2 ] n. The transformation of [Cu(bmtp)Cl 2 ] n into [Cu 3 (bmtp) 2 Cl 6 (H 2 O) 2 ] n is observed in ethanol. According to single crystal X-ray analysis, [Cu(bmtp)Cl 2 ] n was obtained as a mixture of polymorphic forms. They are all 1D coordination polymers, in which polymeric chains include Cu 2 Cl 4 units linked to each other by two bridging ligands via the tetrazole ring N4 atoms. [Cu 3 (bmtp) 2 Cl 6 (H 2 O) 2 ] n presents a 2D coordination polymer, including Cu 3 Cl 6 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. [ABSTRACT FROM AUTHOR]

Abstract: For the first time, tetrazolate complexes have been prepared by direct synthesis. Two novel homo- and heterometallic mixed-ligand complexes, Cu(en)(tz)2 and Cu(en)2Zn(tz)4, have been synthesized using tetrazole (Htz), ethylenediamine (en), metallic copper and zinc oxide as starting materials. Both tetrazolates were characterized by single-crystal X-ray diffraction, IR spectroscopy and thermal analysis. The complexes present 1D coordination polymers, with tetrazolate anions acting as both monodentate and bridging ligands. [Copyright &y& Elsevier]

Abstract: The products of the alkylation of sodium 4-nitro-1,2,3-triazolate with ethyl bromide were investigated using 1H, 13C, and 15N NMR spectroscopy. It was found that alkylation proceeds on the triazole nitrogen atoms giving a mixture of three isomeric N-ethyl-4-nitro-1,2,3-triazoles. The molar ratio of N1, N2, and N3-alkylation products was 4:8:1. The formation of a minor N3-isomer, namely 1-ethyl-5-nitro-1,2,3-triazole was confirmed by X-ray structural analysis of single crystals of its tetranuclear copper(II) complex obtained by reaction of copper(II) chloride dihydrate with a mixture of the N2 and N3-isomers. [Copyright &y& Elsevier]

Triazol-3-yl-1 H -tetrazole ligands show bridging coordination modes giving coordination polymers under action of copper(II) chloride. The peculiarity of complexation of 1-(1,2,4-triazol-3-yl)-1 H -tetrazole is the transformation of the tetrazole cycle under interaction with CuCl 2 /HCl leading to 3-amino-1,2,4-triazolium complex. 1-(1,2,4-Triazol-3-yl)-1 H -tetrazole (trt) and 1-(1- tert -butyl-1,2,4-triazol-3-yl)-1 H -tetrazole (btrt) were synthesized by heterocyclization of corresponding amines with triethyl orthoformate and sodium azide. The interaction of trt with copper(II) chloride in ethanol in the presence of hydrochloric acid was found to result in 1D coordination polymer [CuCl 2 (trt)(H 2 O)] n · n H 2 O. N - tert -butylated ligand btrt reacts with the copper salt in ethanol giving 2D coordination polymer [CuCl 2 (btrt)] n. Tetrazole ring-opening reaction with the formation of [CuCl 2 (3-amino-1,2,4-triazolium) 2 ][CuCl 4 ]·2H 2 O was observed in the interaction of trt with copper(II) chloride in aqueous hydrochloric acid. The temperature-dependent magnetic susceptibility measurements of [CuCl 2 (btrt)] n revealed that the copper(II) ions were weakly ferromagnetically coupled showing a coupling constant J of 1.2 cm−1. [ABSTRACT FROM AUTHOR]

Free radical fragmentation (FRF) reactions taking place in hydroxyl-containing (HC) biologically relevant substances can make a substantial contribution to the consequences resulting from irradiation of biosystems. HC organic compounds under radiolysis of their aqueous solutions undergo fragmentation that cause damage to carbohydrates, HC lipids and proteins. It has been established earlier that the HC lipids being subjected to radiolysis undergo such fragmentation, giving phosphatidic acid (PA). Accumulation of PA in cancer cells promotes their proliferation. The aforesaid is an important incentive to perform the search for the substances capable of producing an effective regulative action on the probability of FRF reactions occurrence. The object pursued in this study was investigation of the effects produced by azoles on formation of the end products during radiolysis of aqueous solutions of glycerol-1-phosphate (G1F), free radical transformations of that models HC lipids fragmentation. We established ability of nitroazoles to inhibit fragmentation of G1F. This fact open up a new possibility to enhance efficacy of radiation therapy by introducing agents effectively blocking the radiation-induced processes leading to formation of products promoting cancer cell proliferation. [ABSTRACT FROM AUTHOR]