Structure and polymeric nature of zinc(II) and cobalt(II) phosphino-thionates

Abstract

The degradation in solution of zinc(II) and cobalt(II) phosphinothionate polymers, M(R₂PSO)₂(R = Et, Buⁿ, or Ph) is dependent on concentration, solvent medium, temperature, and nature of the organic groups bonded to the phosphorus atoms. Three-dimensional X-ray analyses of Co(Ph₂PSO)₂ and Zn(Buⁿ₂PSO)₂ have been carried out. Crystals of Co(Ph₂PSO)₂ are monoclinic, space group P2₁/c, with cell dimensions a= 14·96 ± 0·03, b= 23·38 ± 0·04, c= 17·58 ± 0·03 Å, β= 127·8 ± 0·3°, Z= 8. The structure was solved by the heavy-atom method, and refined by block-diagonal least-squares to R 0·099 for 2330 independent reflexions. The crystal consists of polymeric chains with alternate single and triple bridging phosphinothionate groups between distorted tetrahedral cobalt atoms. Two chains, which repeat identically after four metal atoms, run through the unit cell along the [001] direction. The values of the skeleton bond lengths and angles are in the ranges: Co–S 2·318–2·356(7), Co–O 1·94–1·98(1), P–S 2·00–2·02(1), P–O, 1·51–1·52(2)Å; Co–S–P 88·7–106·2° and Co–O–P 139·9–153·3°. The angles around the cobalt atoms range from 96·1–123·0°. Crystals of Zn(Buⁿ₂PSO)₂ are disordered. The results indicate a polymeric structure with alternate single and triple bridging phosphinothionate groups between tetrahedral metal atoms similar to that found in the crystals of Co(Ph₂PSO)₂.

The structure and properties of phosphinothionate polymers are compared with those of the analogous phosphinates and phosphinodithioates.