Zinkkomplexe eines neuen N,N, O‐Liganden

Zinc Complexes of a New N, N, O Ligand The tridentate ligand N, N(2‐dimethylaminoethyl)‐3, 5‐di‐tert.‐butyl‐salicylaldimine ( L H) results from the corresponding salicylic aldehyde and N, N‐dimethyl ethylenediamine. With zinc salts it forms the mononuclear halide complexes [ L ZnCl ˙ CH₃OH] ( 1 ) and [ L ZnI ˙ CH₃OH] ( 2 ) and the presumably polymeric acetate [ L ZnOCOCH₃] ( 3 ). With diethyl zinc and diphenylphosphoric acid it yields the phosphate complex [ L Zn‐OPO(OPh)₂ ˙ CH₃OH] ( 4 ). The coordination of the complexes, which is between trigonal bipyramidal and square pyramidal, and the character of the five donors in the phosphate complex represent the transition state of a hydrolytic substrate cleavage in a zinc enzyme.     

Synthesis,crystal structure,and spectroscopic and thermal properties of the polymeric compound catena‐poly[[bis(2,4‐dichlorobenzoato)zinc(II)]‐μ‐isonicotinamide]

Zinc(II) carboxylates with O‐, S‐ and N‐donor ligands are interesting for their structural features, as well as for their antibacterial and antifungal activities. The one‐dimensional zinc(II) coordination complex catena‐poly[[bis(2,4‐dichlorobenzoato‐κO)zinc(II)]‐μ‐isonicotinamide‐κ²N¹:O], [Zn(C₇H₃Cl₂O₂)₂(C₆H₆N₂O)]_n, has been prepared and characterized by IR spectroscopy, single‐crystal X‐ray analysis and thermal analysis. The tetrahedral ZnO₃N coordination about the Zn^II cation is built up by the N atom of the pyridine ring, an O atom of the carbonyl group of the isonicotinamide ligand and two O atoms of two dichlorobenzoate ligands. Isonicotinamide serves as a bridge between tetrahedra, with a Zn...Zn distance of 8.8161 (7) Å. Additionally, π–π interactions between the planar benzene rings contribute to the stabilization of the extended structure. The structure is also stabilized by intermolecular hydrogen bonds between the amino and carboxylate groups of the ligands, forming a two‐dimensional network. During thermal decomposition of the complex, isonicotinamide, dichlorobenzene and carbon dioxide were evolved. The final solid product of the thermal decomposition heated up to 1173 K was metallic zinc.     

Coordination behavior of symmetrical hexadentate O2N2S2-donor Schiff bases toward zinc (II): synthesis,characterization, and crystal structure

Two series of zinc(II) complexes of two Schiff bases (H₂L¹ and H₂L²) formulated as [Zn(HL¹/HL²)]ClO₄ (1a and 1b) and [Zn(L¹/L²)] (2a and 2b), where H₂L¹ = 1,8-bis(salicylideneamino)-3,6-dithiaoctane and H₂L² = 1,9-bis(salicylideneamino)-3,7-dithianonane, have been prepared and isolated in pure form by changing the chemical environment. Elemental, spectral, and other physicochemical results characterize the complexes. A single crystal X-ray diffraction study confirms the structure of [Zn(HL¹)]ClO₄ (1a). In 1a, zinc(II) has a distorted octahedral environment with a ZnO₂N₂S₂ chromophore.     

Monomere Tripod–Zink-Thiolat-Komplexe

Monomeric Tripod–Zinc Thiolate Complexes Reaction of the pyrazolylborate-zinc complex Tp^Cum,MeZn–OH with the corresponding thiols yielded the stable complexes Tp^Cum,MeZn–SR ( 1 : R = Ph, 2 : R = CH₂–Ph, 3 : R = CH₂–CH₂–Ph) which are further representatives of this class of compounds. Using the ligand tris(benzimidazolylmethyl)amine (BIMA), zinc perchlorate, and the corresponding sodium thiolates, the cationic complexes (BIMA)Zn–SR (R = Ph, CH₂Ph) were obtained, which were isolated as [(BIMA)Zn–S–Ph] BPh₄ ( 4 ) and [(BIMA)Zn–S–CH₂Ph] ClO₄ ( 5 ). A structure determination of 4 confirmed the pseudotetrahedral coordination geometry for this new type of compounds.     

Unsystematische Zinkchemie: zufällige Bildung und Struktur von Zn6(SC6F5)10(BPPAE)2

Non‐systematic Zinc Chemistry: Accidental Formation and Structure of Zn₆(SC₆F₅)₁₀(BPPAE)₂ The reaction between pyridine‐2‐carbaldehyde and ammonia‐contaminated zinc‐bis(pentafluorothiophenolate) yielded, beside the expected 1 : 1 adduct, small amounts of the hexanuclear cluster Zn₆(SC₆F₅)₁₀(BPPAE)₂. Its ligand BPPAE (1,2‐bis‐pyridine‐2‐yl‐2[(pyridine‐2‐ylmethylene)‐amino]‐ethenolate) results from condensation of three molecules of pyridine‐2‐carbaldehyde with one molecule of ammonia. The Zn₆ cluster consists of two centrosymmetrically arranged Zn₃ units which contain three differently coordinated zinc ions in ZnS₄, ZnS₂ON and ZnSON₃ environments.     

Ungewöhnliche Bildung und Struktur eines O‐Sulfinato‐Zinkkomplexes

Unusual Formation and Structure of a O‐Sulfinato Zinc Complex Whereas the reaction between hydrotris[(N‐xylyl)‐thioimidazolyl]borato‐zinc perchlorate ([ L· Zn‐OClO₃]) and ethanethiolate under an inert atmosphere leads to the thiolate complex [ L· Zn‐SC₂H₅], the same reaction in air produces the sulfinato complex [ L· Zn‐O‐S(O)‐C₂H₅] ( 1 ). 1 is the first fully characterized sulfinato‐zinc complex. Its structure determination has confirmed the unusual coordination of the sulfinato ligand via one of its oxygen atoms.     

Polymeric di­aqua­bis­[μ4‐1,3,5‐benzenetri­carboxyl­ato(3–)](μ‐4,4′‐bi­pyridine)­trizinc(II)

The solvothermal reaction of zinc(II) acetate with 1,3,5‐benzene­tri­carboxyl­ic acid and 4,4′‐bi­pyridine in 1‐butanol and acetic acid solution gives the title complex, [Zn₃(C₉H₃O₆)₂(C₁₀H₈N₂)(H₂O)₂]_n. There are two different coordination environments for the Zn atom, namely ZnNO₂(H₂O) and ZnO₄; in the latter case, the Zn atom lies on a twofold symmetry axis. Carboxyl­ate‐bridged Zn₃(O₂C)₆ clusters are connected through 1,3,5‐benzene­tri­carboxyl­ate and 4,4′‐bi­pyridine ligands (which lie about inversion centers), yielding a three‐dimensional framework.     

New mixed-anion zinc(II) complexes, [Zn(phen)2(CCl3COO)(H2O)](NO3) and [Zn(bpy)2(CH3COO)](ClO4) · H2O; synthesis,characterization and crystal structures

Zinc(II) complexes with 1,10-phenanthroline (phen) and 2,2′-bipyridine (bpy) containing two different anions have been synthesized and characterized by elemental analysis, IR-, ¹H?NMR-, ¹³C?NMR spectroscopy. The single crystal X-ray data of [Zn(phen)₂(CCl₃COO)(H₂O)](NO₃) show the complex to be monomeric and the Zn atom with an unsymmetrical six-coordinate geometry, coordinated by four nitrogen atoms of “phen”, one trichloroacetate and one water. The crystal structure of [Zn(bpy)₂(CH₃COO)](ClO₄)?·?H₂O shows each zinc atom chelated by the nitrogen atoms of “bpy” and also two oxygen atoms of acetate. From the infrared spectra and X-ray crystallography, it is established that coordination of the carboxylate group to zinc is different for trichloroacetate and acetate.     

A novel dimeric zinc(II) complex with a tripodal peptide ligand: a structure stabilized by ligand sharing

The crystal structure of a novel dimeric zinc(II) complex, [ZnL(H₂O)]₂(ClO₄)₂·4H₂O (L?=?N-(bis(2-pyridyl)methyl)-2-pyridinecarboxamide), has been determined by X-ray diffraction. In this complex each planar N_py–N_amido–N_py moiety of the ligand coordinates to one zinc ion and the pendant pyridine of one [ZnL] unit completes the coordination sphere of a [ZnL] neighbor. Units of the complex are connected in a two-dimensional network by intermolecular hydrogen bonds. The thermodynamic properties of the ligand with bivalent metal ions Co(II), Ni(II), Cu(II) and Zn(II) were studied by potentiometric titration and the order of the stability constants is in agreement with the Irving–Williams series. The dimeric complex is stabilized through ligand sharing, as confirmed by the crystal structure and thermodynamic properties.     

First‐row transition metal–pyridine (py)–sulfate [(py)xM](SO4) complexes (M = Ni,Cu and Zn): crystal field theory in action

The crystal structures of three first‐row transition metal–pyridine–sulfate complexes, namely catena‐poly[[tetrakis(pyridine‐κN)nickel(II)]‐μ‐sulfato‐κ²O:O′], [Ni(SO₄)(C₅H₅N)₄]_n, (1), di‐μ‐sulfato‐κ⁴O:O‐bis[tris(pyridine‐κN)copper(II)], [Cu₂(SO₄)₂(C₅H₅N)₆], (2), and catena‐poly[[tetrakis(pyridine‐κN)zinc(II)]‐μ‐sulfato‐κ²O:O′‐[bis(pyridine‐κN)zinc(II)]‐μ‐sulfato‐κ²O:O′], [Zn₂(SO₄)₂(C₅H₅N)₆]_n, (3), are reported. Ni compound (1) displays a polymeric crystal structure, with infinite chains of Ni^II atoms adopting an octahedral N₄O₂ coordination environment that involves four pyridine ligands and two bridging sulfate ligands. Cu compound (2) features a dimeric molecular structure, with the Cu^II atoms possessing square‐pyramidal N₃O₂ coordination environments that contain three pyridine ligands and two bridging sulfate ligands. Zn compound (3) exhibits a polymeric crystal structure of infinite chains, with two alternating zinc coordination environments, i.e. octahedral N₄O₂ coordination involving four pyridine ligands and two bridging sulfate ligands, and tetrahedral N₂O₂ coordination containing two pyridine ligands and two bridging sulfate ligands. The observed coordination environments are consistent with those predicted by crystal field theory.     

Construction of 1D and 2D Zinc Coordination Polymers Based on Organic Carboxylate Anions and Flexible Imidazole‐Containing Ligand

Two novel zinc coordination polymers {[Zn(PhCOO)₂(bmix)]}_n 1 and {[Zn(ada)(bmix)]·(H₂O)₂}_n 2 (bmix = 1,4‐bis(2‐methylimidazole‐1‐ylmethyl)benzene, H₂ada = adipic acid), were obtained by the hydrothermal reactions of bmix and zinc acetate with two carboxylate anions, respectively. Structural analyses show that complex 1 possess a one‐dimensional helix chain structure, 2 takes two‐dimensional corrugated (4,4) layer motif. The structural differences of two complexes indicate that organic carboxylate anions play important roles in the formation of such zinc(II) coordination architectures.     

Zinkkomplexe des N,N,S‐Liganden 2‐Mercaptobenzyl‐bis‐(2‐pyridylmethyl)amin

Zinc Complexes of the N,N,S‐Ligand 2‐Mercaptobenzyl‐bis‐(2‐pyridylmethyl)amine An improved synthesis of the title ligand MBPA–H has made its complex chemistry accessible. With diethyl zinc it forms the reactive ethyl complex (MBPA)Zn–C₂H₅ ( 1 ) whose reaction with phenol leads to (MBPA)Zn–OC₆H₅ ( 2 ). With zinc nitrate the labile compound (MBPA)Zn–ONO₂ ( 3 ) is formed which in turn is converted with thiophenolate into (MBPA)Zn–SC₆H₅ ( 4 ). Structure determinations of 2 and 3 have confirmed severely deformed trigonal‐bipyramidal coordinations of the zinc atom whose ligation patterns correspond to those in some hydrolytic zinc enzymes.     

Synthesis and characterization of zinc benzoate complexes through combined solid and solution phase reactions

A combined solid and solution phase methodology for the synthesis of a series of mononuclear and polynuclear zinc benzoate complexes is described. The substituent on the aromatic ring and the effect of solvent on deciding the composition of the complexes is presented. From the 4-substituted benzoic acids 4-methylbenzoic acid (ptolH), 4-nitrobenzoic acid (pnitrobenH) and 4-chlorobenzoic acid (pchlorbenH), the mononuclear complexes [Zn(ptol)₂(H₂O)₂], [Zn(pnitroben)₂(H₂O)(DMSO)₂] and [Zn(pchlorben)₂py)₂] (where DMSO = dimethylsulfoxide, py = pyridine) have been synthesized and structurally characterised. Zinc complexes from the reaction of zinc sulfate heptahydrate with 3-methylbenzoic acid (mtolH) and 2-methylbenzoic acid (otolH), the dinuclear complexes [Zn₂(μ²-mtol)₄(py)₂], [Zn₂(μ²-otol)₄(py)₂], pentanuclear complex [Zn₅(μ²-mtol)₆(mtol)₂(μ³-OH)₂ (py)₂] and tetranuclear complex [Zn₄(μ²-otol)₆(μ⁴-O) (DMSO)₂], have been prepared by varying the reaction conditions and the complexes have been structurally characterized.     

Complexes of zinc,cadmium and mercury(II) with the zwitter-ionic form of NN′-ethylenebis (salicylideneimine)

The Schiff base NN′-ethylenebis(salicylideneimine), H₂ salen reacts with hydrous and anhydrous Zinc, Cadmium and Mercury(II) salts to give complexes M(H₂ salen)X₂·nH₂O (M = Zn, Cd, Hg; XCl, Br, I, NO₃; MZn, X₂SO₄; n = 0?2). Spectroscopic and other evidence indicated that; (i) halide and sulphate are coordinated to the metal ion, whereas the nitrate group is ionic in mercury nitrate compound and covalently bonded in zinc and cadmium nitrato complexes, (ii) the Schiff base is coordinated through the negatively charged phenolic oxygen atoms and not the nitrogen atoms, which carry the protons transferred from phenolic groups on coordination, (iii) therefore the coordination numbers suggested are 4-, in mercury and 4- or 6- in zinc and cadmium Schiff base complexes.     

Synthesis,Crystal Structures,and Thermal Properties of New Zinc(II) Thiocyanato Coordination Compounds

Reaction of zinc(II) thiocyanate with pyrazine, pyrimidine, pyridazine, and pyridine leads to the formation of new zinc(II) thiocyanato coordination compounds. In bis(isothiocyanato‐N)‐bis(μ₂‐pyrazine‐N,N) zinc(II) ( 1 ) and bis(isothiocyanato‐N)‐bis(μ₂‐pyrimidine‐N,N) zinc(II) ( 2 ) the zinc atoms are coordinated by four nitrogen atoms of the diazine ligands and two nitrogen atoms of the isothiocyanato anions within slightly distorted octahedra. The zinc atoms are connected by the diazine ligands into layers, which are further linked by weak intermolecular S ··· S interactions in 1 and by weak intermolecular C–H ··· S hydrogen bonding in 2 . In bis(isothiocyanato‐N)‐bis(pyridazine‐N) ( 3 ) discrete complexes are found, in which the zinc atoms are coordinated by two nitrogen atoms of the isothiocyanato ligands and two nitrogen atoms of the pyridazine ligands. The crystal structure of bis(isothiocyanato‐N)‐tetrakis(pyridine‐N) ( 4 ) is known and consists of discrete complexes, in which the zinc atoms are octahedrally coordinated by two thiocyanato anions and four pyridine molecules. Investigations using simultaneous differential thermoanalysis and thermogravimetry, X‐ray powder diffraction and IR spectroscopy prove that on heating, the ligand‐rich compounds 1 , 2 , and 3 decompose without the formation of ligand‐deficient intermediate phases. In contrast, compound 4 looses the pyridine ligands in two different steps, leading to the formation of the literature known ligand‐deficient compound bis(isothiocyanato‐N)‐bis(pyridine‐N) ( 5 ) as an intermediate. The crystal structure of compound 5 consists of tetrahedrally coordinated zinc atoms which are surrounded by two isothiocyanato anions and two pyridine ligands. The structures and the thermal reactivity are discussed and compared with this of related transition metal isothiocyanates with pyrazine, pyrimidine, pyridazine, and pyridine.     

Syntheses and Molecular Structures of 2-(1-Methyliminoethyl)phenolato Zinc Complexes

2-(1-Methyliminoethyl)phenol ( 1 a ) reacts with diethyl zinc to give bis[2-(1-methyliminoethyl)phenolato]zinc ( 3 ) via [2-(1-methyliminoethyl)phenolato]ethylzinc ( 2 ) as an intermediate. The complex 3 is also formed in the reaction of bis(trimethylsilyl)amide zinc with 1 a . The compounds were characterized by microanalysis, NMR (¹H, ¹³C) and IR spectroscopy. X-ray structure analysis of the compounds 2 and 3 revealed that both compounds form in the solid state dimeric species where the monomeric units are bridged via two oxygen atoms forming a planar Zn₂O₂ ring with tetrahedral [ZnO₂NC] and trigonal-bipyramidal [ZnO₃N₂] coordination of the zinc atom, respectively.     

[Ni(C6N2H14)2][Zn4(H2O)(HPO3)5]: A new open-framework zinc phosphite with intersecting 8-, 12- and 16-ring channels

A new three-dimensional (3-D) zinc phosphite with Zn/P ratio of 4/5, [Ni(C₆N₂H₁₄)₂][Zn₄(H₂O)(HPO₃)₅] (1), has been prepared by using self-assembled nickel complexes as the structure-directing agents. Its structure is built up from strict alternation of ZnO₄ tetrahedra and HPO₃ pseudo-pyramids, resulting in an open framework with multi-directional intersecting 8-, 12- and 16-ring channels. The unique nickel complexes Ni(DACH)₂ (DACH=1,2-diaminocyclohexane) only involving the cis-DACH acting as ligands are self-assembled under hydrothermal conditions, and act as the structure-directing agents (SDAs) to direct the formation of compound 1. Nickel complexes reside in the channels in a manner that the hydrophobic ends of the cis-DACH molecules exclusively protrude into the 16-ring pores and the amino groups closely interact with the charged inorganic framework through weak H-bonds. The interesting arrangements of nickel complexes imply a feasible approach to the design and synthesis of extra-large pore materials.     

Zinc(II) complexes of 1,3-bis(2-pyridylmethylthio)propane: Anion dependency, crystal structure and DNA binding study

Zinc(II) complexes of the formula [Zn(L)(X)₂] (where X = Cl⁻, N₃⁻, NCO⁻ and SCN⁻ (1a-d, respectively)) and {[Zn(L)(ClO₄)(H₂O)](ClO₄)}_n (2), were isolated in the pure form on the reaction of 1,3-bis(2-pyridylmethylthio)propane (L) with different zinc(II) salts. All the complexes were characterized by physicochemical and spectroscopic tools. The X-ray crystallographic analyses of the complexes 1d and 2 showed that the former is mononuclear while complex 2 is a 1D coordination polymer, {[Zn(L)(ClO₄)(H₂O)](ClO₄)}_n, due to a different coordination mode of the tetradentate ligand L. The zinc(II) ions present an octahedral coordination geometry in both compounds, which is more distorted in the mononuclear complex 1d. The study indicates that the counter anion of the zinc(II) salt used as reactant leads to a different type of complex when isolated as a crystalline material. A spectroscopic study of the interaction of complex, 2 with calf thymus-DNA (CT-DNA) in Tris-HCl buffer showed a significant non-intercalative interaction with a binding constant (K_b) of 4.7 × 10⁴ M⁻¹, and the linear Stern-Volmer quenching constant (K_sv) and the binding sites (n) were found to be 1.3 × 10³ and 0.92 respectively, calculated from ethidium bromide (EB) fluorescence displacement experiments.     

Structural and spectroscopic characterization of two new blue luminescent pyridylbenzimidazole zinc(II) complexes

Luminescent metal complexes are used in photooptical devices. Zinc(II) complexes are of interest because of the ability to tune their color, their high thermal stability and their favorable carrier transport character. In particular, some zinc(II) complexes with aryl diimine and/or heterocyclic ligands have been shown to emit brightly in the blue region of the spectrum. Zinc(II) complexes bearing derivatized imidazoles have been explored for possible optoelectronic applications. The structures of two zinc(II) complexes of 5,6‐dimethyl‐2‐(pyridin‐2‐yl)‐1‐[(pyridin‐2‐yl)methyl]‐1H‐benzimidazole (L), namely dichlorido(dimethylformamide‐κO){5,6‐dimethyl‐2‐(pyridin‐2‐yl‐κN)‐1‐[(pyridin‐2‐yl)methyl]‐1H‐benzimidazole‐κN³}zinc(II) dimethylformamide monosolvate, [ZnCl₂(C₂₀H₁₈N₄)(C₃H₇NO)]·C₃H₇NO, (I), and bis(acetato‐κ²O,O′){5,6‐dimethyl‐2‐(pyridin‐2‐yl‐κN)‐1‐[(pyridin‐2‐yl)methyl]‐1H‐benzimidazole‐κN³}zinc(II) ethanol monosolvate, [Zn(C₂H₃O₂)₂(C₂₀H₁₈N₄)]·C₂H₅OH, (II), are reported. Complex (I) crystallized as a dimethylformamide solvate and exhibits a distorted trigonal bipyramidal coordination geometry. The coordination sphere consists of a bidentate L ligand spanning axial to equatorial sites, two chloride ligands in equatorial sites, and an O‐bound dimethylformamide ligand in the remaining axial site. The other complex, (II), crystallized as an ethanol solvate. The Zn^II atom has a distorted trigonal prismatic coordination geometry, with two bidentate acetate ligands occupying two edges and a bidentate L ligand occupying the third edge of the prism. Complexes (I) and (II) emit in the blue region of the spectrum. The results of density functional theory (DFT) calculations suggest that the luminescence of L results from π*←π transitions and that the luminescence of the complexes results from interligand charge‐transfer transitions. The orientation of the 2‐(pyridin‐2‐yl) substituent with respect to the benzimidazole system was found to have an impact on the calculated HOMO–LUMO gap (HOMO is highest occupied molecular orbital and LUMO is lowest unoccupied molecular orbital).     

Synthesis,characterization, and crystal structures of cobalt(II), copper(II), and zinc(II) complexes of a bidentate iminophenol

A bidentate iminophenol (HL = 2-((4-methoxyphenylimino)methyl)-4,6-di-tert-butylphenol derived from condensation of 4-methoxyaniline and 3,5-di-tert-butyl-2-hydroxybenzaldehyde) was mixed with divalent metal salts to form the corresponding mononuclear metal complexes [M^II(L)₂] (M = Co (1), Cu (2), and Zn (3)). The complexes are characterized by different spectroscopic and analytical tools. X-ray crystal structures of the complexes revealed homoleptic mononuclear complexes with MN₂O₂ coordination. The cobalt(II) (1) and zinc(II) (3) complexes display a pseudo-tetrahedral coordination geometry, whereas the copper(II) complex (2) exhibits a distorted square-planar coordination. The zinc(II) complex (3) emits at 460 nm with a twofold enhancement of emission with respect to the free iminophenol.