COPPER(II)-SULFUR INTERACTIONS IN PYRIDINE- AND IMIDAZOLE-CONTAINING DISULFIDE COMPLEXES. SYNTHESES, SPECTRA, AND SOLUTION EQUILIBRIA.

Abstract

Synthetic, spectroscopic, and potentiometric studies on the copper(II) complexes of pyridine-, quinoline-, and imidazole-ring-containing disulfides and related compounds have been made with emphasis on copper(II)-sulfur interactions. In the presence of copper(II), disulfide ligands, (RCH//2NHCH//2CH//2S-)//2, where R equals 4-imidazolyl (IMAD), 2-pyridyl (PMAD), 6-methyl-2-pyridyl (MPAD), and 2-quinolyl (QMAD), are more stable in acid solution than in neutral-alkaline solution. A stable 1:1 copper(II) complex, Cu(IMAD)(ClO//4)//2-H//2O, was isolated as crystals from aqueous solution, whereas a binuclear complex, Cu//2(PMAD)Cl//4, was obtained as crystals in ethanol. The Cu(II)-IMAD systems exhibit a single d-d peak at 585 nm indicative of a CuN//4 chromophore but no charge transfer (CT) band in the region 300-900 nm.