Synthesis of the tetraruthenium carbido cluster [Ru4(H)2C(CO)12]via mixed ruthenium–gold carbido intermediates; X-ray crystal structures of [Ru4C(CO)12(AuPMe2Ph)2], [Ru4C(CO)12(I)(AuPEt3)], and [Ru4(H)C(CO)12(AuPPh3]

Abstract

The action of CO on the pentanuclear carbido cluster [Ru₅C(CO)₁₄(AuPR₃)₂][PR₃= PEt₃(2), PMe₂Ph (3)](80 atm, 60 °C) affords the tetranuclear carbido cluster [Ru₄C(CO)₁₂(AuPR₃)₂][PR₃= PEt₃(4) PPh₃(5), PMe₂Ph (6)], which exhibits a carbide-centred, ‘butterfly’ Ru₄C core with both the ‘wing-tip’ and ‘hinge’ Ru atoms bridged by AuPR₃ groups; the ‘hinge’ bridging AuPR₃ group may be replaced by reaction with I₂ or HI to give [Ru₄C(CO)₁₂(I)(AuPR₃)][PR₃= PEt₃(7), PPh₃(8)] and [Ru₄(H)C(CO)₁₂(AuPR₃)][PR₃= PEt₃(9), PPh₃(10)], respectively, and the subsequent reaction of (9) and (10) with [BH₄]^– removes the remaining AuPR₃ group, acidification affording the tetraruthenium carbide [Ru₄(H)₂C(CO)₁₂](11)