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The reaction of the ligand [1-(4-((1H-benzo[d][1,2,3]triazol-2(3H)-yl)methyl)benzyl)-1H-benzo[d][1,2,3]triazole] (L) with CuCl2 in acetonitrile yields a dinuclear copper(II) complex [Cu2Cl4L2]center dot 2CH(3)CN (1.2CH3CN), which has been characterized by elemental analysis, powder and single crystal X-ray diffraction, thermal gravimetric analysis as well as IR, UV-Vis and EPR spectroscopy The crystal structure reveals that the metal coordination geometry is best described as square planar. (C) 2011 Elsevier B. V. All rights reserved. Inorganica Chimica Acta

The reaction of Zn(NO(3))(2)center dot 3(H(2)O) with trans-aconitic acid (H(3)L), in presence of chelating 1,10-phenanthroline, leads to the formation of a dinuclear unit {[Zn(HL)(phen)(H(2)O)]center dot 3(H(2)O)}(2). The lattice water molecules are assembled as a centrosymmetric hexamer. The crystal structure, thermal studies, theoretical calculations, and the factors that stabilize this water hexamer are presented. (C) 2010 Elsevier B.V. All rights reserved. Inorganic Chemistry Communications

The reaction of metal(II) nitrates with oxamide-N,N'-diacetic acid (HA) in aqueous media under mild conditions, leads to the formation of novel coordination polymers formulated as {[M(H(2)L)(H(2)O)(x)]. 2(H(2)O)}(n) where M = Co(II), x = 4 (1); Ni(II), x = 4 (2); Zn(II), x = 3 (3); Cd(II), x = 3 (4): Ca(II), x = 2 (5). Compounds 1-4 are 1D polymers with the ligand being doubly deprotonated and coordinated through the carboxylic edges. Compound 5 is a 2D polymer with the ligand utilizing all of the available oxygen atoms for coordination. In all cases extended hydrogen bonding leads to the formation of 3D supramolecular architectures. The structures are discussed in terms of topological description. The synthesized compounds were also characterized with spectroscopic techniques and their stability was checked with thermal studies. (C) 2009 Elsevier Ltd. All rights reserved. Polyhedron

The reactions of methyl 2-pyridyl ketone oxime, (py)C(Me)NOH, with MSO4 center dot xH(2)O (M = Zn, x = 7; M = Cd, x = 8/3), in the absence of an external base, have been investigated. The synthetic study has led to the two new complexes [Zn(SO(4)){(py)C(Me)NOH}(H(2)O)(3)] center dot H(2)O (1 center dot H(2)O) and [Zn(2)(SO(4))(2){(py)C(Me)NOH} (4)] center dot (py)C(Me)NOH [2 center dot (py)C(Me)NOH], and the coordination polymer [Cd(SO(4)){(py)C(Me)NOH} (H(2)O)](n) center dot [Cd(SO(4)){(py)C(Me)NOH}(H(2)O)(2)] n (3). In the three complexes the organic ligand chelates through its nitrogen atoms. The sulfate anion in 1 center dot H(2)O is monodentate; the complex molecule is the mer isomer considering the positions of the aqua ligands. The Zn(II) centers in 2 center dot (py)C(Me)NOH are bridged by two syn, anti eta(1): eta(1): mu(2) SO(4)(2-) ligands; each metal ion has the cis- cis-trans disposition of the coordinated sulfate oxygen, pyridyl nitrogen and oxime nitrogens, respectively. The molecular structure of 3 is unique consisting of two different linear and ladder - type chains. pi-pi stacking interactions and/or hydrogen bonds lead to the formation of interesting supramolecular architectures in the three complexes. The thermal decomposition of complex 3 has been studied. Characteristic vibrational (IR, Raman) bands are discussed in terms of the nature of bonding and the structures of the three complexes. (C) 2008 Elsevier B. V. All rights reserved. Inorganica Chimica Acta

The initial use of the picolinate (pic(-))/sulfate "blend" in metal chemistry has yielded two neutral coordination polymers. Complexes [Zn-2(SO4)(pic)(2)(H2O)(3)](n) (1) and [Cd-2(SO4)(pic)(2)(H2O)(3)](n) center dot nH(2)O (2 center dot nH(2)O) were prepared by the reaction of MSO4 center dot xH(2)O [M = Zn, x = 7; M = Cd, x = 8/3] with one equivalent of picolinic acid (picH) in aqueous solution in the absence of external base. The structures of both compounds have been determined by single-crystal X-ray crystallography. Complex I consists of helical chains which interact through hydrogen bonds and stacking interactions to form a 3D, 5-connected network. Complex 2 - nH(2)O consists of ribbons that are crosslinked by the sulfato ligands to give a 2D, 4-connected network. Hydrogen bonds and stacking interactions lead to the formation of a 3D supramolecular architecture. In both coordination complexes, the pic ligand adopts two different bridging coordination modes (2.111 and 2.201 in 1; 2.211 and 2.201 in 2 center dot nH(2)O), while the SO42- behaves as a bidentate bridging 2.1100 (Harris notation) ligand. The Zn(II) complex has 5- and 6-coordinate metal ions, whereas 6- and 7-coordinate Cd-11 atoms are present in 2 - nH(2)O. Characteristic vibrational (IR, Raman) bands are discussed in terms of the known structures, and the coordination modes of the pic(-) and SO42- ligands. The thermal decomposition of the Cd(11) compound has also been studied. (C) 2007 Elsevier Ltd. All rights reserved. Polyhedron

The C-terminal blocked tetrapeptides SHHK- and SAHK-, which represent the fragments produced from the hydrolysis of the hexapeptides' -TASHHK-, -TESHHK-, and -TESAHK- complexes with Ni(II), were synthesized and their interactions with Ni(II) ions were studied potentiometrically and spectroscopically. Both tetrapeptides interact strongly with Ni(II) ions leading to square-planar complexes with 4N {NH2,2N(-),N-im} coordination. The stability of the Ni-SHHK- complex is about 2 orders of magnitude higher than the Ni-SAHK- complex. Spectroscopic evidence and theoretical predictions suggest the positioning of the free imidazole ring, in the Ni-SHHK- complex, above the coordination plane, explaining the extra stability of the complex. (C) 2004 Elsevier Inc. All rights reserved. J Inorg Biochem

A systematic investigation of the CuCl2/Mebta (Mebta = 1-methylbenzotriazole) reaction system is described, involving the determination of the influence of the Cu-II:Mebta ratio, the nature of solvent and the presence of counterions on the identity of the reaction products. As a consequence, complexes [Cu2Cl4(Mebta)(4)] (1), [CuCl2(Mebta)(2)] (2), {[Cu2Cl4(Mebta)(2)]}(n) (3), [Cu4OCl6(Mebta)(4)] . 0.25H(2)O (4 . 0.25H(2)O) and [Cu2Cl2(Mebta)(6)](ClO4)(2) (5) have been isolated and structurally characterized by single-crystal X-ray studies. Mebta behaves as a monodentate ligand binding through N(3). I is a dinuclear complex, the structure of 2 consists of discrete monomeric units, and that of 3 is composed of linear, well-separated polymeric chains of Cu-II atoms. The molecules of 4 . 0.25H(2)O have a central mu(4)-oxide ion surrounded tetrahedrally by four Cu-II atoms. In the cations of 5 the two Cu-II centres are asymmetrically bridged by two chloro ligands, with three Mebta molecules completing five coordination at each metal. Complexes were characterized by spectroscopic (IR, far-IR, solution UV/Vis) and thermal decomposition (TG, DTG, and DTA) techniques. Variable-temperature magnetic susceptibility data for 1, 3 and 5 showed intramolecular (1, 5) and intrachain (3) ferromagnetic exchange interactions. Estimates of the J parameters, experimentally derived, were in close agreement with a new magneto-structural criterion developed by us, holding for bis(mu-chloro) copper(II) dimers. A comparison between the CuCl2/Mebta and CuBr2/Mebta systems is also presented. (C) 2004 Elsevier B.V. All rights reserved. Inorganica Chimica Acta

[Cd(phen)(2)(CA)](n) (I, where phen is 1,10-phenanthroline and CA(2-) is the dianion of 3,6-dichloro-2,5-dihydroxy-1,4-benzoquinone) has been synthesized and its crystal structure has been determined by single-crystal X-ray diffraction at room temperature. The crystal of I is built from infinite chains of chloranilate-bridged cadmium(II) leading to a zig-zag structure, with the phenanthroline ligands being stacked between the chains. These interactions assist the formation of a closely packed 3D structure. The coordination environment of cadmium(II) - very scarce in its chemistry - is square antiprismatic. The polymer was also characterized with spectroscopic (IR, Raman, DRS) and thermogravimetric (TG, DTA) techniques. (C) 2004 Elsevier Ltd. All rights reserved. Polyhedron

The hexapeptides AcThrAlaSerHisHisLysNH(2), AcThrGluAlaHisHisLysNH(2), AcThrGluSerAlaHisLysNH(2) and AcThrGluSerHisAlaLysNH(2) which represent modifications of the 120-125 sequence of histone H2A were synthesized and their interactions with Cu(II) ions were studied with potentiometric and spectroscopic (UV-Vis, EPR and CD spectroscopy) studies. All peptides coordinate Cu(II) efficiently. At physiological pH, AcThrAlaSerHisHisLysNH(2) forms dimeric species while the rest of the peptides form monomers. The dimer is formed when Cu(II) ions coordinate equatorially through the imidazole nitrogen of the His-4 residue and the amide nitrogens of the Ser-3 and His-4 residues, plus the imidazole nitrogen of the His-5 residue of a second peptide molecule after deprotonation. At higher pH peptides AcThrAlaSerHisHisLysNH(2) and AcThrGluAlaHisHisLysNH(2) are using the second histidine residue for coordination at the apical position while Cu(II) ions coordinate equatorially with the imidazole nitrogen of His-5 or His-4 and three amido nitrogens with the peptides AcThrGluSerAlaHisLysNH(2) and AcThrGluSerHisAlaLysNH(2) (C) 2002 Elsevier Science B.V. All rights reserved. Inorganica Chimica Acta

His-Val-His and His-Val-Gly-Asp are two naturally occuring peptide sequences, present at the active site of Cu,Zn-superoxide dismutase (Cu,Zn-SOD). The interactions of His-Val-His=A (copper binding site) with Cu(II) and of His-Val-Gly-Asp=B (zinc binding site) with Zn(II) have been studied by using both potentiometric and spectroscopic methods (visible, EPR, NMR). The stoichiometry, stability constants and solution structure of the complexes formed have been determined. The binding modes of the species [CuAH](2+) and [CuA](+) were characterized by histamine type of coordination. [CuA](+) is further stabilized by the formation of a macrochelate with the involvement of the imidazole of the C-terminal histidine. The existence of macrochelate results in a slight distortion of the coordination geometry providing good base for the development of enzyme models. The enhanced stability of the macrochelate suppresses the formation of bis-complexes as well as the amide deprotonation. This process, however, takes place at higher pH resulting in the formation of the 4 N- coordinated [NH2,N-,N-,N(im)] species [CuAH(2-)](-). On the other hand, in the case of the Zn(Il)-His-Val-Gly-Asp system, coordination takes place at the terminal carboxylate in species [ZnBH2](2+). Monodentate binding occurs via the N-terminal imidazole in [ZnBH](+) while histamine type of coordination is possible in [ZnB], [ZnB2H](-) and [ZnB2](2-) species. Amide deprotonation does not take place in the case of Zn2+, hydroxo-complexes are formed instead. (C) 2001 Elsevier Science B.V. All rights reserved. J Inorg Biochem

The 1:2:1 reaction of CdCl2 . 2.5H(2)O with 3,4-dihydroxybenzoic acid (3,4-H(3)dhb) and KOH in (PrOH)-O-n-H2O gave the unique, seven-coordinate cadmium(II) complex [Cd(3,4-H(2)dhb)(2)(H2O)(3)]. HCl .(3,4-H(3)dhb). 2.5H(2)O as one of the products. Crystal structure and Cd-13 NMR studies showed that 3.4-H(2)dhb(-) behaves as a bidentate chelate with ligated atoms being the carboxylate oxygens, but that seven-coordination is not retained in aqueous solution. Copyright (C) 1997 Elsevier Science Ltd. Polyhedron