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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]

Hydrolytically stable PdII and PtII complexes supported by acyclic diaminocarbene ligands represent a novel class of structural organometallic anticancer agents exhibiting nanomolar antiproliferative activity in a panel of cancer cell lines (IC50 0.07–0.81 μM) and up to 300‐fold selectivity for cancer cells over normal primary fibroblasts. The lead drug candidate was 300 times more potent than cisplatin in vitro and showed higher efficacy in reducing the growth of aggressive MDA‐MB‐231 xenograft tumors in mice. [ABSTRACT FROM AUTHOR]

Boron‐dipyrromethene dyes (BODIPY) are of great interest nowadays mostly due to their valuable optical properties. Nevertheless, no systematic research of the optical property dependence on the structure of dyes has been performed yet. In this work, analysis of the available quantum‐chemical methods for BODIPY optical property calculations has been carried out. The accuracy of eight DFT functionals has been studied. The solvation effects upon excitation have been considered within two schemes. The methods that predict the absorption and emission spectra of BODIPY derivatives with high accuracy have been proposed. Using the suggested methods, the influence of nature of substituents and their position in the BODIPY core on the optical spectra of the dyes has been studied. A complex pattern of red‐ and blue‐shifts in optical spectra in dependence of nature and position of substituents has been revealed. The results of this work provide the way for efficient design of BODIPY derivatives with desired optical properties. [ABSTRACT FROM AUTHOR]

The functionalization of (R,R)-S,S′-di-tert-butylferrocene-1,1′-disulfoxide by deprotolithiation-electrophilic trapping sequences was studied towards polysubstituted, enantiopure derivatives for which the properties were determined. While the 2,2′-disubstituted ferrocene derivatives were obtained as expected, subsequent functionalization of the 2,2′-di(phenylthio) and 2,2′-bis(trimethylsilyl) derivatives occurred primarily at the 4- or 4,4′-positions. This unusual regioselectivity was discussed in detail in light of pKa values and structural data. The less sterically hindered 2,2′-difluorinated derivative yielded the expected 1,1′,2,2′,3,3′-hexasubstituted ferrocenes by the deprotometallation-trapping sequence. Further functionalization proved possible, leading to early examples of 1,1′,2,2′,3,3′,4,4′-octa, nona and even decasubstituted ferrocenes. Some of the newly prepared ferrocene-1,1′-disulfoxides were tested as ligands for enantioselective catalysis and their electrochemical properties were investigated. [ABSTRACT FROM AUTHOR]

A new tetrazole ligand, 5‐amino‐2‐isopropenyltetrazole, was prepared by regioselective alkylation of 5‐aminotetrazole with allyl bromide in sulfuric acid followed by dehydrobromination of intermediate 5‐amino‐2‐(1‐bromopropan‐2‐yl)tetrazole. 5‐Amino‐2‐isopropenyltetrazole (L) was found to react with copper(II) chloride to generate complex [CuL2Cl2]n. The ligand and its complex were characterized by single crystal X‐ray and thermal analyses. Complex [CuL2Cl2]n presents 1D coordination polymer, formed at the expense of double chlorido bridges between neighbouring octahedral coordinated CuII cations. Tetrazole ligand acts as monodentate ligand coordinated by CuII cations via the heteroring N4 atoms only. Magnetic studies revealed that the copper(II) ions were weakly antiferromagnetically coupled. Natural bond orbital analysis was performed to explain the structural peculiarities of the ligand. Its basicity and the relative stability of the protonated forms were investigated using MO calculations. [ABSTRACT FROM AUTHOR]

Invited for the cover of this issue are Tatiyana Serebryanskaya, Mikhail Kinzhalov and co‐workers at St. Petersburg State University, the Research Institute for Physical Chemical Problems, Belarusian State University, Togliatti State University and Blokhin National Medical Research Center of Oncology. The image depicts the shield of Pallas Athena with the structure of a palladium carbene complex that protects against triple‐negative breast cancer. Read the full text of the article at 10.1002/chem.202400101. [ABSTRACT FROM AUTHOR]

The article titled "Metal-(Acyclic Diaminocarbene) Complexes Demonstrate Nanomolar Antiproliferative Activity against Triple-Negative Breast Cancer" discusses the use of a palladium compound to target aggressive tumors while sparing normal cells and tissues. The authors draw inspiration from the protective figure of Pallas Athena, which symbolizes the original meaning of the word "palladium." The research article provides more detailed information on this topic and can be accessed using the provided DOI. [Extracted from the article]

The purpose of the study is to design synthetic methodologies, especially directed deprotometalation using polar organometallic reagents, to access polysubstituted ferrocenesulfoxides. From enantiopure 2-substituted (SiMe3, PPh2) S-tert-butylferrocenesulfoxides, a third substituent was first introduced at the 5 position (SiMe3, I, D, C(OH)Ph2, Me, PPh2, CH2NMe2, F) and removal of the trimethylsilyl group then afforded 2-substituted ferrocenesulfoxides unreachable otherwise. Attempts to apply the "halogen dance" reaction to the ferrocenesulfoxide series led to unexpected results although rationalized in light of calculated pKa values. Further functionalizations were also possible. Thus, new enantiopure, planar chiral di- and trisubstituted ferrocenes have been obtained, in addition to several original 2-substituted, 2,3- and 2,5-disubstituted, 2,3,5-trisubstituted and even 2,3,4,5-tetrasubstituted ferrocenesulfoxides, also enantiopure. [ABSTRACT FROM AUTHOR]

The novel iron-oxide nanoparticles (NPs) stabilized with triethanolammonium oleate were produced. The specimens were divided into two groups: the top NPs (extracted from the supernatant) and the bottom NPs (nanoparticles sedimented at the bottom of the flask during centrifugation), respectively. The XRD and Mössbauer studies revealed a presence of the Fe3O4 phase in both types of nanoparticles. Furthermore, the formation of maghemite layer on the surface of nanoparticles was observed. Average particle sizes determined from TEM and XRD studies were lower than the superparamagnetic limit for the magnetite NPs. For glycerol dispersions of both types of NPs, when exposed to 100 kHz external magnetic field, a significant heat release was observed. Furthermore, the contrasts of T1- and T2-weighted MR images were significantly dependent on the concentration of NPs in their water solutions. Additionally, the reductions of the relaxation times were different for the top and the bottom NPs. The viability studies of the colon cancer cells have shown low cytotoxicity of both types of NPs due to their coating with triethanolammonium oleate, which confirm the possibility to apply the NPs for MRI-guided hyperthermia. Moreover, the presence of NPs did not cause greatest increase of the number of apoptotic cells in the human dermal fibroblasts' culture and has stimulated proliferation of those cells, revealing great potential of the NPs in regenerative medicine. [ABSTRACT FROM AUTHOR]

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: A density functional theory (DFT) calculations have been carried out to study the adsorption of silver di-, tetra- and octamers on stoichiometric rutile (110) surface. In order to determine the most reliable model of adsorption, two different approaches have been used: a cluster model and a periodic one. Comparison of the calculation results with the experimental data revealed that the periodic model exhibits better results than the cluster one. The most stable adsorption sites for each silver cluster have been found. It has been shown that hollow-sites are preferable to adsorption over chain oxygen atoms. Population and charge analysis have been carried out to determine the binding mechanisms for the most stable structures. The adsorbed clusters are coupled with the surface through two types of binding in case of the hollow-sites. The first type is the overlap between HOMO of the cluster and unfilled surface level which consists mostly of Ti atom 3d-orbitals. The charge is partly transferred from cluster to the surface, thus all adsorbed clusters have positive charges. The value of charge correlates with binding energies. The second binding type is the interaction of MOs of the cluster with surface eigenstates localized on chain oxygen atoms. This interaction is equally strong as compared to that of the first type and leads to deformation of silver clusters structure during adsorption. The second type of binding only occurs during the adsorption over chain oxygen atoms. Thus, the binding energies are smaller in this case. The presence of filled levels in the band gap has been revealed for some structures. It can be one of the reasons of high photocatalytic activity typical for Ag/TiO2 systems. [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]

The interaction of 1‐phenyl‐1,4‐dihydro‐5H‐tetrazol‐5‐one (Hpto) with ethylenediamine (en) and metallic copper in ethanol in the open air was found to yield molecular complexes [Cu(en)2(pto)2] (1) or [Cu2(en)2(EtOH)2(pto)4] (2) depending on the reagents ratio. Deprotonated tetrazol‐5‐one, i.e 1‐phenyltetrazol‐5‐olate anion (pto) acts as a monodentate ligand coordinated to the metal via the tetrazole ring N4 atom in mononuclear complex 1, and as a bridging ligand coordinated via the tetrazole ring N4 and N3 atoms in binuclear complex 2. The latter was found to be a paramagnet, with a very weak antiferromagnetic exchange interaction between copper ions. [ABSTRACT FROM AUTHOR]

Few studies have been reported on the synthesis of ferrocenesulfonates up to now. Here, we describe the use of ortho‐deprotometalation and "halogen dance" reactions to easily reach original derivatives. Further functionalizations using cross‐coupling and metal/halogen exchange were also performed from iodinated derivatives. Finally, while the electrochemical properties of selected ferrocenesulfonates were evaluated and compared with the corresponding sulfonamide derivatives, halogen bonds were observed at the solid state for iodinated derivatives of ferrocenesulfonates. [ABSTRACT FROM AUTHOR]

Novel platinum(II) and palladium(II) chlorido complexes with tetrazole derivatives 1-(2-hydroxyethyl)tetrazole (het) and 1-[tris(hydroxymethyl)methyl]tetrazole (thm), viz. cis-[Pt(het)2Cl2], trans-[Pt(het)2Cl2], trans-[Pt(thm)2Cl2], trans-[Pd(het)2Cl2], and trans-[Pd(thm)2Cl2], were synthesized. The compounds were characterized by elemental and high-resolution electrospray ionization (HRESI) mass spectrometry, high-performance liquid chromatography (HPLC), 1H, 13C and 195Pt nuclear magnetic resonance (NMR) spectroscopy, thermal analyses, and Infrared (IR) spectroscopy. Molecular and crystal structures of trans-[PdL2Cl2] and trans-[PtL2Cl2] (L = het, thm) were established by single-crystal X-ray analysis. The complex cis-[Pt(het)2Cl2] was found to undergo cis–to–trans isomerization upon heating in acetonitrile solution and in the solid state. The synthesized complexes show rather high water solubility lying in the range of 2–10 mg/L. [ABSTRACT FROM AUTHOR]

Various 2‐, 3‐ and 1'‐substituted iodoferrocenes were reacted with acetamide in the presence of copper(I) iodide (1 equiv), N,N'‐dimethylethylenediamine (1 equiv), tripotassium phosphate (2 equiv) in dioxane at 90 °C for 14 h, and allowed a large range of original 1,2‐, 1,3‐ and 1,1'‐disubstituted ferrocenes to be obtained. The results were compared as a function of the substituent and its position on the ring. DFT calculations revealed higher activation barrier for the oxidative addition in the ferrocene series when compared with classical planar aromatics. Structure‐property relationships were applied to rationalize the reactivity of the different iodoferrocenes. [ABSTRACT FROM AUTHOR]

Novel platinum(II) and palladium(II) chlorido complexes with tetrazole derivatives 1-(2-hydroxyethyl)tetrazole (het) and 1-[tris(hydroxymethyl)methyl]tetrazole (thm), viz. cis-[Pt(het)2Cl2], trans-[Pt(het)2Cl2], trans-[Pt(thm)2Cl2], trans-[Pd(het)2Cl2], and trans-[Pd(thm)2Cl2], were synthesized. The compounds were characterized by elemental and high-resolution electrospray ionization (HRESI) mass spectrometry, high-performance liquid chromatography (HPLC), 1H, 13C and 195Pt nuclear magnetic resonance (NMR) spectroscopy, thermal analyses, and Infrared (IR) spectroscopy. Molecular and crystal structures of trans-[PdL2Cl2] and trans-[PtL2Cl2] (L = het, thm) were established by single-crystal X-ray analysis. The complex cis-[Pt(het)2Cl2] was found to undergo cis–to–trans isomerization upon heating in acetonitrile solution and in the solid state. The synthesized complexes show rather high water solubility lying in the range of 2–10 mg/L. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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]

A novel N,N′‐alkylene‐bridged bis(5‐pyridyltetrazole) ligand, namely 2,5‐bis[5‐(2‐pyridyl)‐tetrazol‐2‐yl]‐2,5‐dimethylhexane (bpt), was prepared by regioselective N2‐alkylation of 5‐(2‐pyridyl)tetrazole with 2,5‐dimethylhexane‐2,5‐diol in perchloric acid. The ligand bpt was found to react with copper(II) chloride to give the dinuclear complex [Cu2(bpt)Cl4]. According to single‐crystal X‐ray analysis of the complex, bpt acts as a chelating ligand, coordinated by the metal through the tetrazole ring N4 and the pyridine ring nitrogen atoms. In the complex molecule, two copper atoms are linked by double chlorido bridges, and ligand bpt plays the role of the third bridge. The temperature‐dependent magnetic susceptibility measurements of the complex revealed that the copper(II) ions were weakly antiferromagnetically coupled showing a coupling constant J of –1.04 cm–1. [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]

Different 2‐arylated oxazolo[4,5‐b]pyrazines, obtained by palladium(II)‐catalyzed domino reaction from 2,3‐dichloropyrazine and the corresponding carboxamides, were functionalized by deprotometallation. Employing lithium 2,2,6,6‐tetramethylpiperidine, in order to form a lithio derivative, and then trapping it by iodolysis, proved to be inefficient. However, the presence of a zinc‐based in situ trap allowed most substrates to be functionalized. Deprotonation of the pyrazine ring was observed in the presence of tolyl and anisyl groups at the oxazole 2‐position. In contrast, with chlorophenyl and thienyl groups in this 2‐position, deprotonation rather occurred on these groups either competitively or exclusively. The regioselectivities were discussed in the light of calculated pKa values of the substrates in THF. Finally, in the case of 2‐phenyloxazolo[4,5‐b]pyrazine, we converted the mixture of 5‐ and 6‐iodinated products into the corresponding 5,6‐diiodide, which was further functionalized by a double Suzuki coupling. [ABSTRACT FROM AUTHOR]

1-R-Tetrazoles (R ​= ​Et, i -Pr, t -Bu) were found to react with copper(II) tetrafluoroborate hexahydrate and copper(II) nitrate tetrahydrate giving the complexes [Cu 2 L 8 (H 2 O) 2 ]X 4 , where L ​= ​1-R-tetrazole, X ​= ​BF 4 − or NO 3 −. Single crystal X-ray analysis showed that the complexes comprised dinuclear cations [Cu 2 L 8 (H 2 O) 2 ]4+, with six tetrazole ligands showing monodentate N4-coordination, and two ones providing N3,N4 bridges between the copper(II) cations; water molecules complete the distorted octahedral coordination of metal ions. Magnetic susceptibility measurements revealed that the copper(II) ions were very weakly antiferromagnetically coupled. Сomplex [Сu 2 L 8 (H 2 O) 2 ](BF 4) 4 (L ​= ​1-isopropyltetrazole) was found to exhibit a temperature induced reversible single-crystal to single-crystal polymorphic phase transition. For this complex, adiabatic calorimetry was used to find the standard thermodynamic characteristics of this transition as well as the standard thermodynamic functions of the compound in the temperature range of 80–370 ​K. Additionally, mononuclear complex of the composition [CuL 6 ](BF 4) 2 (L ​= ​1-ethyltetrazole) was obtained during the investigation and structurally characterized. Dicopper(II) complexes with N3,N4-bridging coordination of 1-alkyltetrazoles show weak antiferromagnetic coupling. Complex with 1-isopropyltetrazole exhibits a temperature induced reversible single-crystal to single-crystal polymorphic phase transition for which standard thermodynamic functions were determined. [Display omitted] • Dicopper(II) complexes with N3,N4-bridging coordination of 1-alkyltetrazoles were synthesized and characterized by X-ray analysis. • Copper(II) ions is weakly antiferromagnetically coupled in dinuclear complexes. • Dicopper(II) complex with 1-isopropyltetrazole exhibits a temperature induced single-crystal polymorphic phase transition. • Standard thermodynamic functions of complex and its transition were determined by adiabatic calorimetry. [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]

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] (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 neighboring 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 neighboring copper(II) cations are linked by single bromide bridges. [ABSTRACT FROM AUTHOR]

Two methods were compared to convert ferrocene into N,N-diisopropylferrocenecarboxamide, N,N-diethylferrocenecarboxamide, N,N-dimethylferrocenecarboxamide, and (4-morpholinocarbonyl)ferrocene, namely, deprotometalation followed by trapping using dialkylcarbamoyl chlorides and amide formation from the intermediate carboxylic acid. The four ferrocenecarboxamides were functionalized at C²; in the case of the less hindered and more sensitive amides, recourse to a mixed lithium-zinc 2,2,6,6-tetramethylpiperidino-based base allowed us to achieve the reactions. Halogen migration using lithium amides was next optimized. Whereas it appeared impossible to isolate the less hindered 3-iodoferrocenecarboxamides, 3-iodo-N,N-diisopropylferrocenecarboxamide proved stable and was converted to new 1,3-disubstituted ferrocenes by Suzuki coupling or amide reduction. DFT calculations were used to rationalize the results obtained. [ABSTRACT FROM AUTHOR]

Various aromatic ketones were first functionalized next to the carbonyl function by deprotolithiation in the presence of a zinc salt followed by iodolysis. The outcome of the reactions was analyzed, and in particular their regioselectivity in the light of the calculated pKa values. Various halogenated ketones were next involved in copper-catalyzed twofold C-N bond formation to obtain fused systems based on 2-aminopyrimidines. Besides a potential antibacterial effect, 2-aminobenzothiopyrano[4,3,2-de]quinazoline was shown to inhibit PIM1 (IC50: 0.61 μM) and CDK2/cyclin A (IC50: 2.0 μM) kinases. [ABSTRACT FROM AUTHOR]

A new catalyst for cross-coupling synthesis of 1,4-diphenylbutadiyne- 1,3 was prepared by thermolysis of copper(II) poly-5-vinyltetrazolate. It presents heterogeneous catalyst, in which copper nanoparticles are supported on polymeric matrix surface. The catalyst is recovered, recycled and shows high catalytic activity in cross-coupling synthesis of 1,4-diphenylbutadiyne-1,3. The reaction proceeds in aerobic conditions at room temperature in the presence of pyridine. [ABSTRACT FROM AUTHOR]

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 N4–C5 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. [ABSTRACT FROM AUTHOR]

This review provides comprehensive analysis of literature data on the heterocyclization reaction of primary amines, orthoesters, and azides, which can be used for the preparation of tetrazole, its 1-mono- and 1,5-disubstituted derivatives. [ABSTRACT FROM AUTHOR]

The macrocyclic binuclear tetrazole, 2,2,5,5-tetramethyl-12-oxa-1,6,7,8,16,17,18,19-octaazatricyclo[13.2.1.16,9]nonadeca-7,9(19),15(18),16-tetraene (L), reacts with copper(II) chloride or copper(II) tetrafluoroborate hexahydrate to give complexes [Cu3Cl6L2] (1) or [CuL2(H2O)2](BF4)2(H2O) (2), respectively. According to single crystal X-ray analysis, both complexes were found to be coordination polymers. In the crystal structure of complex 1, there are neutral linear bibridged trinuclear units Cu3Cl6, in which the copper atoms are linked together by double chlorine bridges. Neighboring Cu3Cl6 units are bonded to each other by two bridging macrocyclic ligands L due to coordination bonds Cu-N between terminal copper atoms of Cu3Cl6 units and the tetrazole ring nitrogen atoms of ligands L to form polymeric chains. In complex 2, the copper atom is bonded to three ligands L via the tetrazole ring nitrogen atoms, and to two water molecules, with formation of a square-pyramidal coordination of the metal. In this complex, one of two independent ligands L shows monodentate coordination, whereas another ligand plays the role of a bridge between two neighboring copper atoms being responsible for formation of polymeric cationic chains [CuL2(H2O)2] n 2n+. A complex system of hydrogen bonds connects the chains and the anions BF4 - into a three-dimensional network. The temperature-dependent magnetic susceptibility measurements of complex 1 revealed that the copper(II) ions were ferromagnetically coupled showing a coupling constant J of 50 cm-1. [ABSTRACT FROM AUTHOR]

A series of isostructural dinickel complexes of the type [Ni 2 (L Me2H4 )][X] 2 (where (L Me2H4 ) 2− represents a 28-membered macrocyclic N 6 S 2 donor ligand, X = ClO 4 − ( 1a ), I − ( 1b )) and [Ni 2 (L Me2H4 )( μ -L′)][X] (X = ClO 4 − , L′ = F − ( 2a ), Cl − ( 3a ), OH − ( 5a ), N 3 − ( 6a ), X = BPh 4 – , L′ = F − ( 2b ), Cl − ( 3b ), OH − ( 5b ), N 3 − ( 6b ), X = Br − , L′ = Br − ( 4 )) have been synthesized and characterized by IR, ESI-MS, UV–vis, cyclic voltammetry, SQUID magnetometry, and X-ray crystallography. The dications in 1a and 1b feature an edge sharing bis(square-pyramidal) N 3 Ni( μ -S 2 )NiN 3 core, while the monocations of 2a - 6b comprise a face-sharing bioctahedral N 3 Ni( μ -S) 2 ( μ -L′)NiN 3 core. The variation of the coordination geometry has a strong impact on the magnetic properties of the Ni complexes. 3a , 4 , and 5a have an S = 2 ground state with a value for the magnetic exchange coupling constant J of +10.06 cm −1 , ( 3a ), J = +12.13 cm −1 ( 4 ) and J = +2.9(1) cm −1 ( 5a ), while 1a , 1b , and 2a have an S = 0 ground state with J = −13.4 cm −1 ( 1a ), −22.8 cm −1 ( 1b ) and J = −0.56 cm −1 ( 2a ) ( H = – 2 JS 1 S 2 ). Broken symmetry density functional theory calculations have been performed to study the individual contributions of the coligand and thiolato-bridges to the overall magnetic behavior. The capability to propagate exchange interactions was found to increase in the order Br − < Cl − < N 3 − < OH − ∼ F − . [ABSTRACT FROM AUTHOR]

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 N4–C5 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. [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]

The dinuclear NiII complex [Ni2(L²)][ClO4]2 (3) supported by the 28-membered hexaaza-dithiophenolate macrocycle (L²)2- binds the N3- ion specifically end-on yielding [Ni2(L²)(μ1,1-N3)][ClO4] (7) or [Ni2(L²)(μ1,1-N3)][BPh4] (8), while the previously reported complex [Ni2L¹(μ1,3-N3)][ClO4] (2) of the 24-membered macrocycle (L¹)2- coordinates it in the end-to-end fashion. A comparison of the X-ray structures of 2, 3, and 7 reveals the form-selective binding of complex 3 to be a consequence of its preorganized, channel-like binding pocket, which accommodates the azide anion via repulsive CH•••π interactions in the end-on mode. In contrast to [Ni2L¹(μ1,3-N3)][ClO4] (2), which features a S = 0 ground state, [Ni2(L²)(μ1,1-N3)][BPh4] (8) has a S = 2 ground state that is attained by competing antiferromagnetic and ferromagnetic exchange interactions via the thiolato and azido bridges with a value for the magnetic exchange coupling constant J of 13 cm-1 (H = −2JS1S2). These results are further substantiated by density functional theory calculations. The stability of the azido-bridged complex determined by isothermal titration calorimetry in MeCN/MeOH 1/1 v/v (log K11 = 4.88(4) at I = 0.1 M) lies in between those of the fluorido- (log K11 = 6.84(7)) and chlorido-bridged complexes (log K11 = 3.52(5)). These values were found to compare favorably well with the equilibrium constants derived at lower ionic strength (I = 0.01 M) by absorption spectrophotometry (log K11 = 5.20(1), 7.77(9), and 4.13(3) for N3-, F-, and Cl- respectively). [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-(tert-Butyl)-1H-tetrazole (L) reacts with copper(ii) tetrafluoroborate hexahydrate to give the complexes [Cu2L8(H2O)2](BF4)4 (1) or [Cu3L6(H2O)6](BF4)6 (2) depending on the reaction conditions. These complexes, as well as compound L, were characterized using single crystal X-ray analysis. Complex 1 was found to comprise a dinuclear complex cation [Cu2L8(H2O)2]4+ (the Ci symmetry point group), with six tetrazole ligands L showing monodentate N4-coordination, and two ligands L providing two tetrazole ring N3,N4 bridges between the copper(ii) cations; water molecules complete the distorted octahedral coordination of the metal ions. Complex 2 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 N3,N4 bridges; central and terminal metal ions show octahedral CuN6 and CuN3O3 coordination cores, respectively. The temperature-dependent magnetic susceptibility measurements of complex 2 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. [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]

1-(Furan-2-ylmethyl)-1 H-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. [ABSTRACT FROM AUTHOR]

The halide binding properties of the cavitand [Ni2(LMe2H4)]2+ (4) are reported. Cavitand 4 exhibits a chelating N3Ni(μ-S)2NiN3 moiety with two square-pyramidal NiIIN3S2 units situated in an anion binding pocket of ~4 Å diameter formed by the organic backbone of the (LMe2H4)2- macrocycle. The receptor reacts with fluoride, chloride (in MeCN/MeOH), and bromide (in MeCN) ions to afford an isostructural series of halogenido-bridged complexes [Ni2(LMe2H4)(μ-Hal)]+ (Hal = F- (5), Cl- (6), and Br- (7)) featuring a N3Ni(μ-S)2(μ-Hal)NiN3 core structure. No reaction occurs with iodide or other polyatomic anions (ClO4-, NO3-, HCO3-, H2PO4-, HSO4-, SO42-). The binding events are accompanied by discrete UV-vis spectral changes, due to a switch of the coordination geometry from square-pyramidal (N3S2 donor set in 4) to octahedral in the halogenido-bridged complexes (N3S2Hal donor environment in 5--7). In MeCN/MeOH (1/1 v/v) the log K11 values for the 1:1 complexes are 7.77(9) (F-), 4.06(7) (Cl-), and 2.0(1) (Br-). X-ray crystallographic analyses for 4(ClO4)2, 4(I)2, 5(F), 6(ClO4), and 7(Br) and computational studies reveal a significant increase of the intramolecular distance between two propylene groups at the cavity entrance upon going from F- to I- (for the DFT computed structure). In case of the receptor 4 and fluorido-bridged complex 5, the corresponding distances are nearly identical. This indicates a high degree of preorganization of the [Ni2(LMe2H4)]2+ receptor and a size fit mismatch of the receptor binding cavity for anions larger than F-. [ABSTRACT FROM AUTHOR]

Complexation of the ambidentate ligand 4-mercaptobenzoate (4-SH-C6H4CO2H, H2mba) by the macrocyclic complex [Ni2L(μ-Cl)]ClO4 (L2- represents a 24-membered macrocyclic hexaazadithiophenolate ligand) has been examined. The monodeprotonated Hmba- ligand reacts with the Ni2 complex in a selective manner by substitution of the bridging chlorido ligand to produce μ1,3-carboxylato-bridged complex [Ni2L(Hmba)]+ (2+), which can be isolated as an air-sensitive perchlorate (2ClO4) or tetraphenylborate (2BPh4) salt. The reactivity of the new mercaptobenzoate complex is reminiscent of that of a "free" thiophenolate ligand. In the presence of air, 2ClO4 dimerizes via a disulfide bond to generate tetranuclear complex [{Ni2L}2(O2CC6H4S)2]2+ (32+). The auration of 2ClO4 with [AuCl(PPh3)], on the other hand, leads to monoaurated complex [Ni2IIL(mba)AuIPPh3]+ (4+). The bridging thiolate functions of the N6S2 macrocycle are deeply buried and are unaffected/unreactive under these conditions. The complexes were fully characterized by electrospray ionization mass spectrometry, IR and UV/vis spectroscopy, density functional theory, cyclic voltammetry, and X-ray crystallography [for 3(BPh4)2 and 4BPh4]. Temperature-dependent magnetization and susceptibility measurements reveal an S = 2 ground state that is attained by ferromagnetic coupling between the spins of the NiII ions in 2ClO4 (J = +22.3 cm-1) and 4BPh4 (J = +20.8 cm-1; H = -2JS1S2). Preliminary contact-angle and X-ray photoelectron spectroscopy measurements indicate that 2ClO4 interacts with gold surfaces. [ABSTRACT FROM AUTHOR]

With the aim of synthesizing biaryl compounds, several aromatic iodides were prepared by the deprotonative metalation of methoxybenzenes, 3-substituted naphthalenes, isoquinoline, and methoxypyridines by using a mixed lithium/zinc-TMP (TMP=2,2,6,6-tetramethylpiperidino) base and subsequent iodolysis. The halides thus obtained, as well as commercial compounds, were cross-coupled under palladium catalysis (e.g., Suzuki coupling with 2,4-dimethoxy-5-pyrimidylboronic acid) to afford various representative biaryl compounds. Deprotometalation of the latter compounds was performed by using the lithium/zinc-TMP base and evaluated by subsequent iodolysis. The outcome of these reactions has been discussed in light of the CH acidities of these substrates, as determined in THF solution by using the DFT B3LYP method. Except for in the presence of decidedly lower p Ka values, the regioselectivities of the deprotometalation reactions tend to be governed by nearby coordinating atoms rather than by site acidities. In particular, azine and diazine nitrogen atoms have been shown to be efficient in inducing the reactions with the lithium/zinc-TMP base at adjacent sites (e.g., by using 1-(2-methoxyphenyl)isoquinoline, 4-(2,5-dimethoxyphenyl)-3-methoxypyridine, or 5-(2,5-dimethoxyphenyl)-2,4-dimethoxypyrimidine as the substrate), a behavior that has already been observed upon treatment with lithium amides under kinetic conditions. Finally, the iodinated biaryl derivatives were involved in palladium-catalyzed reactions. [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]

4-Nitro-1,2,3-triazole was found to react with tert-butanol in concentrated sulfuric acid to yield 1- tert-butyl-4-nitro-1,2,3-triazole as the only reaction product, whereas tert-butylation and tritylation of 4-nitro-1,2,3-triazole in presence of catalytic amount of sulfuric acid in benzene was found to provide mixtures of isomeric 1- and 2-alkyl-4-nitro-1,2,3-triazoles with predominance of N2-alkylated products. A new methodology for preparation of 1-alkyl-5-nitro-1,2,3-triazoles from 1- tert-butyl-4-nitro-1,2,3-triazole via exhaustive alkylation followed by removal of tert-butyl group from intermediate triazolium salts was demonstrated by the example of preparation of 1-methyl-5-nitro-1,2,3-triazole. [ABSTRACT FROM AUTHOR]