Saturated and unsaturated tetraruthenium clusters containing sterically demanding dicyclohexylphosphido ligands: synthesis and structure of [H4Ru4(CO)8(PCy2)4] and [H5Ru4(CO)8(PCy2)3]

The thermal reaction of the dinuclear complex [Ru2(CO)4(O2CH)2(PCy2H)2] with molecular hydrogen in cyclohexane afforded the tetranuclear clusters [H4Ru4(CO)8(PCy2)4] (64e) and [H5Ru4(CO)8(PCy2)3] (62e), both of which have a square-planar arrangement of the metal framework.