Synthesis, characterization and electronic structure of the novel ‘stellated’ octahedral cluster [Co₆(µ₃-S)₇(µ₃-H)(PEt₃)₆]⁺. Crystal and molecular structure of [Co₆(µ₃-S)₇(µ₃-H)(PEt₃)₆]_0.7[Co₆(µ₃-S)₈(PEt₃)₆]_0.3[BPh₄]

Abstract

Full title: Synthesis, characterization and electronic structure of the novel 'stellated' octahedral cluster [Co6(μ3-S)7(μ3-H)(PEt 3)6]+. Crystal and molecular structure of [Co6(μ3-S)7-(μ3-H)(PEt 3)6]0.7[Co6(μ3-S) 8(PEt3)6]0.3[BPh4]. Reaction of Co(O2CMe)2·4H2O with an excess of PEt3 and H2S afforded the novel diamagnetic octahedral cluster [Co6(μ3-S)7(μ3-H)(PEt 3)6]+ together with a minor amount of the known paramagnetic isostructural [Co6(μ3-S)8(PEt3) 6]+. Solid solutions of the two cluster cations have been isolated as the BPh4- salt. The deuteriated derivative [Co6(μ3-S)7(μ3-D)(PEt 3)6]+ has been prepared for comparison. The compounds have been characterized by 1H, 31P NMR, mass spectrometry and electrochemical measurements. The molecular structure of a sample of composition [Co6(μ3-S)7(μ3-H)(PEt 3)6]0.7[Co6(μ3-S) 8(PEt3)6]0.3[BPh4] has been determined by single-crystal X-ray diffraction. It consists of a solid solution of [Co6(μ3-S)7(μ3-H)(PEt 3)6]+ and [Co6(μ3-S)8(PEt3) 6]+. The cation [Co6(μ3-S)7(μ3-H)(PEt 3)6]0.7[Co6(μ3-S) 8(PEt3)6]0.3+ is isostructural with the series [M6(μ3-S)8(PEt3) 6]n+, having a metal-metal separation averaging 2.739(8) Å. The electronic structure of the novel hydridoderivative has been investigated through density functional calculations.