Aladar Valent

COPPER(II) COORDINATION COMPOUNDS: CLASSIFICATION AND ANALYSIS OF CRYSTALLOGRAPHIC AND STRUCTURAL DATA III. DIMERIC COMPOUNDS

Abstract This review summarizes the data for over nine hundred dimeric Cu(II) coordination compounds. There are several types of the bridges, from which doubly bridges by far prevail. The most common ligands are O− and N− donors. From the stereochemical point of view, a square-pyramidal arrangement with different degrees of distortion about Cu(II), is the most common. Several relationships were found between the Cu-Cu distances and the Cu-L-Cu bridge angle and the type of bridging, between the intra-ligand L-Cu-L ring angles and coordination numbers.

Copper(II) salicylideneglycinate complexes as potential antimicrobial agents

Abstract The reaction of an ethanolic solutions of N-salicylideneglycinatoaquacopper(II) hemihydrate with urea, pyridine, 2,4-dimethylpyridine, 3,5-dimethylpyridine, quinoline, 4-methylquinoline, isoquinoline, or 3-methylisoquinoline in an equimolar ratio resulted in solid products containing complexes of the type Cu(salgly)L with distorted square pyramidal coordination polyhedra. The products were characterized by elemental analysis, electronic and EPR spectra, and magnetic susceptibility measurements. Moreover, the crystal and molecular structure of N-salicylideneglycinatoureacopper(II) dimer was determined by single crystal X-ray diffraction methods. The copper(II) atoms are bridged by two phenolic oxygen atoms with a CuCu distance of 3.1093(11) A and CuOCu angle of 94.47(12)°. The antimicrobial effects have been tested on various strains of bacteria, yeasts and filamentous fungi.

Thiohydrazone copper(II) complexes. The relationship between redox properties and superoxide dismutase mimetic activity

The redox behaviour of copper(II) complexes with the open chain ligand, benzilbisthiosemicarbazone, and the macrocyclic one [3,4,10,11-tetraphenyl-1,2,5,8,9,12,13-octaazacyclotetradeca-7,14- dithione- 2,4,9,11-tetraene] has been explored by cyclic voltammetry. The half-wave potential values for the copper(II)/copper(I) redox couple and the spectral data obtained on dimethylsulfoxide (DMSO) solution agree with the superoxide dismutase (SOD)-mimetic activity of the complexes. The macrocyclic complexes show more positive reduction potential and more activity than the open chain derivatives. From our results it follows that the structure and conformation of ligand has influence on the redox potential of central atom in coordination compound. The changes in the coordination sphere are connected with the change of biological function of compounds represented by SOD-mimic activity. In addition, the L1H6 derivatives show quasireversible waves associated to Cu(II)/Cu(III) process.

N-salicylidene- L -glutamatocopper(II) complexes and their antimicrobial effects

Reaction of an ethanolic solution of N-salicylidene- l -glutamatodiaquacopper(II) monohydrate with pyridine, 2-methylpyridine, 4-methylpyridine, 2-aminopyridine, 2,6-diaminopyridine, quinoline, 2-methylquinoline, 4-methylquinoline or 3-methylisoquinoline resulted in solid products containing complexes of the type Cu(sal- l -glu)L with distorted square-pyramidal coordination geometry. The products were characterized by elemental analysis, electronic spectroscopy and magnetic susceptibility measurements. Antimicrobial effects were tested on various strains of bacteria, yeasts and filamentous fungi. To compare the influence of individual ligands (neutral as well as anionic) on their biological activity, copper(II) complexes containing water and a Schiff base derived from salicyldehyde and methyl- and ethyl-esters of l -glutamic acid [Cu(sal-5-Me- l -glu)(H2O)2 and Cu(sal-5-Et-l-glu)(H2O)2] were also prepared and studied. Bioactivities of complexes tested were found to decrease in the sequence bacteria > filamentous fungi > yeasts.

Crystal and electronic structure of aqua(N-salicylidene-methylester-L-glutamato)Cu(II) monohydrate

Abstract The absolute structure of the title compound, CuNC13H17O7, has been determined. The crystal structure consists of the molecular units Cu(N-sal-5-met-L-glu)(H2O) connected by a three-dimensional network of hydrogen bonds. The coordination polyhedron in the complex is approximately square-pyramidal with a pentacoordinated Cu(II) atom. The base of the pyramid is formed by nitrogen and oxygen atoms belonging to the molecule, while the apex of the pyramid contains a weakly bonded oxygen atom of the carboxylic group of another molecule. The B3LYP/SVP method and basis set in Gaussian98 was used for quantum chemical calculation of the nature of Cu–X (X = O, N) bonds. While the calculated dissociation energy of the weakly bonded crystalline water is only 17.2 kJ/mol, the bonding energy of the water molecule coordinating to the Cu atom is 62.3 kJ/mol.

(N-salicylidene-D,L-glutamato) (2-methylimidazole)copper(II).

The title racemic compound, [Cu(C12H11NO5)(C4H6N2)], adopts a square-pyramidal Cu(II) coordination with the tridentate N-salicylideneglutamate Schiff base dianion and the 2-methylimidazole ligand in the basal plane. The apex of the pyramid is occupied by a carboxylic acid O atom from the neighbouring chelate at a distance of 2.479(4)A, leading to infinite one-dimensional chains along the crystallographic a axis. Strong N-H...O and O-H...O hydrogen bonds form a helix parallel to the c axis. The electronic structure of the title compound has also been investigated by the B3LYP method.

Dimeric (isoquinoline)(N-salicylidene-d,l-glutamato)copper(II) ethanol solvate

The title racemic complex, bis[mu-N-(2-oxidobenzylidene)-D,L-glutamato(2-)]bis[(isoquinoline)copper(II)] ethanol disolvate, [Cu(2)(C(12)H(11)NO(5))(2)(C(9)H(7)N)(2)].2C(2)H(6)O, adopts a square-pyramidal Cu(II) coordination mode with a tridentate N-salicylideneglutamato Schiff base dianion and an isoquinoline ligand bound in the basal plane. The apex of the pyramid is occupied by a phenolic O atom from the adjacent chelate molecule at an apical distance of 2.487 (3) A, building a dimer located on the crystallographic inversion center. The Cu...Cu spacing within the dimers is 3.3264 (12) A. The ethanol solvent molecules are hydrogen bonded to the dimeric complex molecules, forming infinite chains in the a direction. The biological activity of the title complex has been studied.

(1-Methylimidazole)(N-salicylidene-rac-glutamato)copper(II)

The title racemic compound, [Cu(C12H11NO5)(C4H6N2)], adopts a square-planar copper(II) coordination mode with the tridentate N-salicylidenglutamato Schiff base dianion and the 1-methylimidazole ligand. Dimers of centrosymmetrically related molecules are formed. The theoretical investigation of the electronic structure of the title compound by the B3LYP method is presented.

Isomers of Organotin Compounds II. Di - to Polymeric Compounds

The dito polymeric organotin compounds cover a wide field, as shown by a recent survey covering the crystallographic and structure data of almost six hundred examples. About 10 % of these compounds exist as isomers and are summarised in this review. Included are distortion (92 %), ligand, cis trans, and η mer isomerism. These are discussed in terms of the coordination about the tin atom, and correlations are drawn between donor atom, bond length and bond angles. Distortion isomers, differing only by degree of distortion in Sn L distances and L Sn L angles, are the most common. The tin atoms are found in the oxidation states, Sn, Sn2 and Sn.

Novel type of Cu(II) complex containing Schiff base

Recently, special interest has been devoted to the group of copper(II) complexes containing Schiff bases, derived from salicylaldehyde and various amino acids, and N-, or O- donor neutral ligands due to their biological activities. From this group of substances the structures of (N- salicylidene-racglutamato)(1-methylimidazole)Cu(II), (N-salicylidenerac-glutamato)(2-methylimidazole)Cu(II), (N-salicylidene-L-glutamato)(2-ethylimidazole)Cu(II) and aqua(Nsalicylidene-methylester-L-glutamato)Cu(II)monohydrate have been determined. Electronic structure of these compounds has been investigated by the B3LYP method. A continuation of these studies is a new complex transbis(ethanol)tetrakis(imidazole)Cu(II)(2+) bis[µ-(N-salicylidene-L-glutamato-N,O)-κO:κO´-(imidazole)Cu(II)](2-)presented here.This complex has quite spectacular structural features. Both ions are located on inverse centre. The cation is mononuclear, while the anion is binuclear. The quantum chemical calculation of the electronic structure has also been done by the B3LYP method.