Heterocyclic Diimine Research Articles

Bonding properties of copper(II)—N chromophores: Molecular and electronic structures of copper(II) complexes containing ethylenediamine and heterocyclic diimine ligands

Mixed ligand ethylenediaminecopper(II) perchlorate complexes, [Cu(en)LL (H 2O)](ClO 4) 2, en = ethylenediamine and LL stands for 2,2′-bipyridine (bipy), 1,10-phenanthroline (phen), and N,N,N′,N′-tetramethylethylenediamine (tmen), have been prepared and characterized by elementary analyses, and electronic, vibrational, and EPR spectroscopic measurements. The crystal and molecular structures of [Cu(en)(bipy) (H 2O)](ClO 4) 2 ( 1) and [Cu(en)(phen)(H 2O)](ClO 4) 2 ( 2) have been determined from single-crystal, three-dimensional X-ray diffraction data. Both complexes, crystallized in triclinic P 1 − group, contain discrete copper(II) cations having a CuN 4 basal plane and a H 2O on the apex. A similar structure was suggested for [Cu(en)(tmen)(H 2O)](H 2O)](ClO 4) 2 ( 3). The single-crystal polarized electronic spectra of 1 and 2 were measured and resolved into a set of three Gaussian component peaks for each spectrum. Gaussian analyses performed on the crystal and the powder LF bands for these complexes yielded a one-electron orbital sequence d xy > d z 2 > d x 2− y 2 > d yz > d xz . Bonding properties of the bidentate ligands are elucidated suggesting virtually no π-interactions between the heterocyclic diimine ligands and the central copper(II) ion in these ethylene-diamine complexes.

Thermal decomposition of metal complexes: VI. Mixed complexes of copper(II) with bidentate or tridentate dicarboxylic acids and heterocyclic diimines or triimines

A thermal decomposition study on a series of mixed complexes of cupric ion with dicarboxylic acids variously substituted (potentially bidentate or tridentate) and heterocyclic diimines or triimines was carried out. It is suggested that the decomposition mechanism is strongly influenced by the aromatic system of both ligands.

Thermodynamics of copper(II) 2,2′-dipyridyl complexes in aqueous solution

The thermodynamic parameters for the chelation of cupric ion with 2,2′-dipyridyl have been redetermined at 25°C and I=0.1 M. Δ G values were obtained by potentiometry with a selective ion electrode and Δ H values by direct calorimetry. Similar studies have been made on the relative hydroxocomplexes. The data obtained are compared with those in the literature and the chelate effect of the heterocyclic diimine is described.

Adducts of Nickel(II) Diethyldithiophosphate with Secondary Amines and Heterocyclic Diimines.

Adducts of Nickel(II) Diethyldithiophosphate with Secondary Amines and Heterocyclic Diimines.