Studies of chelation : VIII. Substitution reactions of tris-(η-alkyne)monocarbonyltungsten complexes with phosphorus and sulphur ligands. Influence of the alkyne ligand

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The η-alkyne complexes [W(CO)(RCCR) 3] (R  Ph, SMe) react with the ditertiary alkylphosphine Me 2PCH 2CH 2PMe 2 (dmpe) in dichloromethane solution at ambient temperature. [W(CO)(MeSCCSMe) 3] produces [W(CO)-(dmpe)(MeSCCSMe) 2] and eventually [W(dmpe)(MeSCCSMe) 2]; with excess dmpe, [W 2(dmpe) 5(MeSCCSMe)] is formed. All of the alkyne ligands are rapidly displaced from [W(CO)(PhCCPh) 3] to give cis-[W(CO) 2(dmpe) 2] as the principal product. Other phosphorus (Ph 3P, Ph 2PCH 2CH 2PPh 2) and sulphur ligands (PhSCH 2CH 2SPh, Me 3CSCH 2CH 2CMe 3) have no detectable reaction with [W(CO)(RCCR) 3] (R  Ph, SMe) under the same conditions.