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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

Three isostructural two-dimensional coordination polymers of the general formula [Ln(2)(CuL)(3)(H2O)(9)]center dot 5.5H(2)O, where Ln = La (1), Nd (2), and Gd (3), have been synthesized and isolated from aqueous solutions and their single-crystal structures determined by X-ray diffraction. The supramolecular interaction between the non-aromatic metallorings plays an important role in stabilizing the structure of these compounds. The thermal stability, reversible solvent uptake, electronic properties and magnetic studies of these compounds are also reported. Crystengcomm

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 combination of terepthaloylbisglycinate (TBG(2-)) and metal ions at room temperature results in the formation of five coordination polymers formulated as [M(mu-TBG)(mu-H(2)O)(H(2)O)(2)]center dot(2)H(2)O, where M = Co (1) and Cu (2), [Mn(mu-TBG)(H(2)O)(4)]center dot 2H(2)O (3), [Cd(mu-TBG)(H(2)O)(3)]center dot 2H(2)O(4) and [Pb(mu-TBG)(H(2)O)(2)]center dot 3H(2)O (5). The dimensionality of the final product is affected by the coordination number of the metal ion. Thermal, reversible solvent uptake, magnetic and catalytic properties of these compounds have been investigated. New Journal of Chemistry

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 title compound, [Cu2Cl4(C10H8N2)(2)], represents the first example of a simple dimeric coordination complex of Cu-II and 2,2'-bipyridine (bpy). The metal is in a five-coordinate distorted square-pyramidal environment, bonded to a 2,2'-bipyridine molecule, two bridging chlorides and one terminal chloride. There is a centre of symmetry at the mid-point of the Cu---Cu vector. Acta Crystallographica Section E-Structure Reports Online

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

The combination of a new pseudopeptidic ligand, transition metal ions, and bridging water molecules results in the formation of [M(mu-TBG)(mu-H2O)(H2O)(2)]center dot 2H(2)O ( M: Cu, Co and H(2)TBG: terephthaloylbisglycine); both compounds show rare two-fold interpenetrated three-dimensional cds-nets and reversible loss of coordinated and lattice water molecules. Chemical Communications

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

We studied the interactions of Ni(II) and Cu(II) ions with the synthetic tetrapeptides SHHK- and SAHK-, which were blocked by amidation making them more realistic models of the hydrolysis peptidic products of the hexapeptides models of H2A histone. A combination of potentiometric and spectroscopic techniques (UV/Vis, CD, NMR and EPR) suggested that at pH > 7 both tetrapeptides coordinated equatorially through the imidazole ring of His in position 3, the N-terminal amino group and the two amide nitrogens existing between these groups {NH2, 2N(-), N-Im} forming 4N square-planar complexes. While in the case of the CuH-1L complex with SHHK- a possible axial coordination of the imidazole ring of His in position 2 was suggested, in the case of the analogous NiH-1L complex a completely different interaction of the same ring with metal ions was observed. As expected these complexes have the same structures with the hydrolysis products produced from the Ni(II) - or Cu(II)-assisted hydrolysis of previously studied hexapeptide models of the C-terminal of histone H2A, due to their predominance at pH > 7.4. In addition, the competition plots presented herein showed that the synthetic tetrapeptides SHHK- and SAHK- have higher affinity towards Ni(II) andCu(II) ions than the previously studied hexapeptides, suggesting that metal ions remain bound to the peptidic products during the hydrolysis cleavage. Thus, it can be concluded that the stability of Ni( II) or Cu( II) complexes with the synthetic tetrapeptides and consequently with the real hydrolysis peptidic products is the driving force of the hydrolysis reaction of H2A histone blocked hexapeptide models, presented in previous studies. Dalton Transactions

510-513 σ. Metal Ligand Interactions

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

519-524 σ. Metal Ligand Interactions

513-516 σ. Metal Ligand Interactions

The coordination properties of Ni(II) ions towards the terminally blocked (CH3CONH- and - CONH2) hexapeptides -TESHHK-, -TASHHK-, -TEAHHK-, -TESAHK- and -TESHAK- were studied by using potentiometric and spectroscopic techniques ( UV/Vis, CD, NMR). The peptides were chosen in such a way as to compare the effect of Glu, Ser and His residues on the stability, the coordination and hydrolytic abilities of the complexes formed. All peptides bind to Ni(II) ions initially through one or two imidazole nitrogens in weakly acidic and neutral solutions forming slightly distorted octahedral complexes. At higher pH values, a series of square-planar complexes are formed, where Ni(II) ions bind simultaneously through an imidazole and three amide nitrogens in an equatorial plane. This proposed conformation includes the participation of only one imidazole nitrogen, in the case of all peptides, in the coordination sphere of Ni(II) ions. In basic solutions, the peptides - TASHHK- and - TESAHK were hydrolyzed in a Ni(II)-assisted fashion. No hydrolytic processes were noticed in peptides - TEAHHK- and - TESHAK- where the Ser or His-5 residues are replaced with the Ala residue. The Ni(II)-assisted hydrolysis of the analogues of - TESHHK- may provide an insight into the novel mechanism of genotoxicity, combining the damage to the nucleosome with the generation of further toxic Ni(II) species. Journal of the Chemical Society-Dalton Transactions

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

Reaction of Cu(ClO4)(2). 6H(2)O with 1-methylbenzotriazole (Mebta) in EtOH yields [Cu(Mebta)(4)(H2O)] (ClO4)(2). 0.4EtOH in ca. 75% yield. The structure of this salt has been determined by single-crystal X-ray crystallography. Mebta behaves as a monodentate ligand binding through N(3). The metal coordination geometry is best described as distorted square pyramidal with the H2O ligand occupying the apical site. The complex was also characterized by molar conductivity, room-temperature effective magnetic moment and spectroscopic (i.r., far-i.r., u.v./vis, e.s.r.) studies. The data are discussed in terms of the nature of bonding and known structure. Comparison between the structural and spectroscopic properties of [Cu(Mebta)(4)(H2O)](ClO4)(2). 0.4EtOH and those of the (CuI)-I-I site of Cu-Zn superoxide dismutase shows that the former can be considered as a fairly good model for the latter. Transition Metal Chemistry

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

Treatment of Fe(NO3)(3).9H(2)O with 1-methylbenzotriazole in EtOH-CH(OEt)(3) gave the unique, oxo-bridged complex [Fe2O(NO3)(4)(C7H7N3)(4)]; crystal structure and Mossbauer studies showed that the molecule has both bidentate and monodentate nitrates and possesses an S = 0 ground state, respectively. Journal of the Chemical Society-Dalton Transactions

By using the ''complexes as ligands'' synthetic strategy and the unique [Pd(LH)2] and [Pt(LH)2] precursors, the novel heterobimetallic polymeric compounds [MPdL2]n and [CuPtL2]n (M = Co, Ni, Cu, Zn, Pt; L2- = the dianion of N,N'-dimethylmonothiooxamide) have been prepared. The vibrational analysis of the complexes is given using various isotopic substitutions. The polymers consist of alternate planar PdO2S2 (or PtO2S2) and tetrahedrally-distorted planar MN4 structural units. Spectroscopy Letters

The reaction of the unexpectedly formed ligand 2-(2'-pyridyl)quinoxaline (L) With CuCl2 in ethanol, followed by recrystallization from methanol, yields the dinuclear copper (II) complex [Cu2Cl4L2]. The crystal structure of this compound shows a bidentate chelating behaviour of L and different (terminal, asymmetric bridging) chloride coordination modes. Some properties of the dimer are also described. Polyhedron

An inorganic model approach to the corrosion inhibition of metals by benzotriazoles has been initiated. The preparation and characterization of monomeric cobalt(II) complexes of the types [CoX2(Mebta)2] (X = Cl, Br, NCS, NO3), (MebtaH)[CoCl3(Mebta)], (MebtaH)2[CoCl4], [Co(NCS)2(Mebta)4], [Co(NCS)2(MeOH)2(Mebta)2] and [Co(NO3)2 L2(Mebta)2] (L = H2O, MeOH), where Mebta = 1-methylbenzotriazole, are described. Four representative complexes have been structurally characterized by single-crystal X-ray diffraction studies; [CoCl2(Mebta)2] (1), trans-[Co(NCS)2(Mebta)4] (5), trans-[Co(NCS)2 (MeOH)2(Mebta)2] (6) and cis-[Co(NO3)2(Mebta)2] (8). Mebta acts as a monodentate ligand binding through N(3). The geometry about cobalt in 1 is tetrahedral, while complexes 5, 6 and 8 have octahedral stereochemistries. The new complexes were also characterized by elemental and thermogravimetric analyses, conductivity measurements, variable-temperature magnetochemistry and spectroscopic (IR, ligand field, low-temperature ESR) methods. The data are discussed in terms of the nature of bonding and known structures. Polyhedron

Synthetic procedures are described that allow access to anilinium salts containing the complex anions [Hg2Cl6]2-, [Hg2Cl4X2]2- (X = Br, I), [CdHgI6]2-, [CdHgI4Br2]2- and [CdHgBr4I2]2-. Isolated dimeric structures are proposed for the new complexes in the solid state, using X-ray powder patterns, Far-IR and Raman spectra. The spectral detail is greatly enhanced in measurements at low temperature (approximately 100 K). Zeitschrift Fur Naturforschung Section B-a Journal of Chemical Sciences

The synthesis of the Ni(II), Pd(II) and Cu(II) complexes of N,N'-bis(aminoalkyl)oxamides (LH2) is described and structures are proposed on the basis of their physical and spectroscopic properties. With Ni(II) and Pd(II) only one complex is formed with general formula NiL or PdL, characterised by coordination through two deprotonated amide N-atoms and two terminal NH2 groups. With Cu(II) it proved possible to obtain three structurally different compounds, depending on the pH, with general formulae Cu(LH2)X2, Cu2(L)X2 and CuL in which X = Cl, Br or NO3. The structure of [Cu2(C8O2N4H16](NO3)2 was solved by means of x-ray diffraction; Mr = 451.33, monoclinic, space group P2(1)/n, a = 9.503(4), b = 7.614(1), c = 10.407(3) angstrom, beta = 98.43(3)-degrees, V = 744.3(7) angstrom 3, Z = 2, Dx = 1.202 g cm-3, mu = 1.33 cm-1, lambda-(MoK-alpha) = 0.71073 angstrom, F(000) = 520, room temperature, R = 0.043, wR = 0.047 for 1080 observed [I greater-than-or-equal-to 3-sigma(I)] not systematically absent reflections out of 1423 measurements and 137 variables. The compound has a conformational chair/boat disorder with 82% in the more stable chair form. Transition Metal Chemistry