Coordinatively unsaturated diruthenium complexes:: Synthesis and X-ray crystal structures of [Ru2(CO)n(μ-H)(μ-PtBu2)(μ-Ph2PCH2PPh2)] (n = 4; 5) and [Ru2(CO)4(μ-CH2)(μ-H)(μ-PtBu2)(μ-Ph2PCH2PPh2)

The reaction of [Ru-2(mu-Co)(CO)(5)(mu-H)(mu (PBu2)-Bu-t)((Bu2PH)-Bu-t)] (2) with dppm yields the dinuclear species [Ru-2(mu-CO)(CO)(4)(mu-H)(mu-(PBu2)-Bu-t) (mu-dppm)] (3) (dppm = Ph2PCH2PPh2). Under thermal or photolytic conditions 3 loses very easily one carbonyl ligand and affords the corresponding electronically and coordinatively unsaturated complex [Ru-2(CO)(4)(mu-H)(mu-(PBu2)-Bu-t)(mu-dppm)] (4). 4 is also obtainable by an one-pot synthesis from [Ru-3(O)(12)], an excess of (Bu2PH)-Bu-t and stoichiometric amounts of dppm via the formation of [Ru-2(CO)(4)(mu-H)(mu-(PBu2)-Bu-t) ((Bu2PH)-Bu-t)(2)] (1) 4 exhibits a Ru-Ru double bond which could be confirmed by addition of methylene to the dimetallacyclopropane [Ru-2(CO)(4)(mu-CH2)(mu-H)(mu-(PBu2)-Bu-t)(mu-dppm)] (5). The molecular structures of 3, 4 and 5 were determined by X-ray crystal structure analyses.