Some reactions of nitrogen bases with cobalt(II) complexes of the bidentate chelate Di(2-pyridyl) sulphide

Abstract

Cobalt(11) compounds containing the chelate di(2-pyridyl) sulphide (dps) of the types Co(dps)X₂ (X = Cl, Br, and I) and Co(dps)₂X₂ (X = Cl, Br, and NCS) have been prepared and investigated. An attempt to prepare cobalt(11) complexes containing mixed chelates such as Co(dps)(4-mepy)₂X₂ (4-mepy = 4-methylpyridine) was unsuccessful. However, a spectrophotometric investigation of the following replacement reactions Co(dps)Cl₂ + 2(N-base) ↔ Co (N-base)₂Cl₂ + dps was carried out in chloroform and room-temperature equilibrium constants were determined. For N-base = 4-mepy, pyridine, 4-ethylpyridine, isoquinoline, 4-benzoylpyridine, quinoline, and 4-cyanopyridine K values were evaluated as 113, 73, 56, 43, 10, 0.7, and 0.03 respectively. For the tetrahedral-octahedral configurational equilibrium Co(4-mepy)₂X₂ + 2(4-mepy) ↔ Co(4-mepy)₄X₂(X = Cl, Br, and I) equilibrium constants have been determined at room temperature in chloroform as 13.2, 12.9, and 8.7 respectively.