Thiol exchange for MO3+(M = Mo or W) centres; synthesis and structure of [PPh4][MO(SCH2CH2S)2]

Abstract

Stoicheiometric thiol exchange between [MO(SPh)₄]^–(M = Mo or W) and HSCH₂CH₂SH provides a convenient synthesis for the [MO(SCH₂CH₂S)₂]^– complexes: the structures of the [PPh₄]⁺ salts of these anions have been determined to provide a clear structural comparison between these homologues [the two anions have very similar dimensions Mo–O 1.678(5), W–O 1.641(10), Mo–S 2.372(3), W–S 2.363(6)Å]; on the basis of e.s.r. spectroscopic studies, it is concluded that [MoO(SCH₂CH₂S)₂]^– is formed when [MoO₄]^2– reacts with HSCH₂CH₂SH and when this dithiol reacts with the oxidised molybdenum centre of xanthine oxidase.