Synthesis and crystal structure of [Ru8(μ5-S)2(μ4-S)(μ3-S)(μ-CNMe2)2(μ-CO)(CO)15] formed via the double sulphur-carbon bond cleavage of dithiocarbamate ligands

Heating cis-[Ru(S₂CNMe₂)₂(CO)₂] and [Ru₃(CO)₁₂] in xylene affords octanuclear [Ru₈(μ₅-S)₂(μ₄-S)(μ₃-S)(μ-CNMe₂)₂(μ-CO)(CO)₁₅] resulting from the double carbon-sulfur bond cleavage of two dithiocarbamate ligands. The structure consists of a tri-edge-bridged square of ruthenium atoms with a further ruthenium atom being bound only to the central bridging atom. Studies suggest that it may be formed via the pentanuclear intermediate [Ru₅(μ₄-S)₂(μ-CNMe₂)₂(CO)₁₁] which is formed in trace amounts.     

Unsymmetrical alkyne binding to a triruthenium centre: Oxidative-addition of diphenyl ditelluride to the furyne cluster [Ru3(CO)7(μ-H)(μ3-η-C4H2O){μ-P(C4H3O)2}(μ-dppm)]

Oxidative-addition of PhTe₂Ph to the furyne cluster [Ru₃(CO)₇(μ-H)(μ₃-η²-C₄H₂O){μ-P(C₄H₃O)₂}(μ-dppm)] (1) results in the isolation of four complexes; (i) the previously reported 54-electron cluster [Ru₃(CO)₆(μ₃-Te)₂(μ-TePh)₂(μ-dppm)] (5) which results from elimination of trifuryl phosphine, (ii) the furenyl cluster [Ru₃(CO)₅(μ-η²-C₄H₃O){μ-P(C₄H₃O)₂}(μ-TePh)₂(μ-dppm)] (6) which results from carbon-hydrogen bond formation and (iii) two new 50-electron complexes [Ru₃(CO)₅(μ-H)(μ₃-η²-C₄H₂O){μ-P(C₄H₃O)₂}(μ-TePh)₂(к²-dppm)] (7) and [Ru₃(CO)₄(μ-H){P(C₄H₃O)₃}(μ₃-η²-C₄H₂O){μ-P(C₄H₃O)₂}(μ-TePh)₂(к²-dppm)] (8) both containing unsymmetrical furyne ligands. The structures of all the new compounds have been unambiguously established by single crystal X-ray crystallography. Further reactivity studies have provided a clear understanding of the relative sequence of the key oxidative-addition and reductive-elimination processes, showing that 6 is an intermediate in the formation of 7. DFT calculations have been used to shed light on the unsymmetrical binding of the furyne ligand in 7 and also to show that the adopted position of the heteroatom within the furyne ring can vary within complexes of this type.