Synthesis and molecular structure of the mixed polymeric cobalt compound [Co3(SCH2CH2S)3(PEt3)3]2[Co2Cl4(µ-O2SEt2)2]

Abstract

The mixed polymeric cobalt compound [Co₃(SCH₂CH₂S)₃(PEt₃)₃]₂[Co₂Cl₄(µ-O₂SEt₂)₂]1 containing two trimers and one dimer was isolated from the reaction of [CoCl(PEt₃)₃] with disodium ethane-1,2-dithiolate in 1,2-dichloroethane. It is monoclinic and crystallizes in space group P2₁/n, with a= 12.481(7), b= 15.70(2), c= 25.84(2)Å, β= 97.85(5)° and Z= 2 from 2436 reflections with I > 3.50σ(I), final R= 0.062. X-Ray diffraction established that the two cobalt atoms in the dimer are linked via the oxygen atoms of the diethyl sulfone forming the eight-membered Co₂O₄S₂ ring with a crystallographic inversion centre through the whole dimer. The observed cleavage of the dithiolate C–S bond together with the formation of the bridging diethyl sulfone are discussed. In the trimer of 1, the Co₃ isosceles triangle is capped by two bidentate SCH₂CH₂S^2– ligands on either side of the plane with the sulfur atoms bridging the two long Co–Co bonds, while the short Co–Co bond is bridged by the third SCH₂CH₂S^2– ligand. Considering the framework of the Co₃P₃(SCH₂CH₂S)₃ unit only, there is a pseudo mirror-image plane passing through the Co₃P₃ plane which bisects the C(31)–C(32) bond. The ¹H NMR spectrum of compound 1 demonstrates the retention of the solid-state structure of the trinuclear species in chloroform solution.