Penta- and hexaruthenium carbonyl 'raft' complexes supported by monocarborane cage ligands

Reaction between PPh4]closo-4-CB8H9] and Ru3(CO)12] in refluxing toluene affords the unprecedented hexaruthenium metallacarborane salt PPh4]2,3,7-{Ru(CO)3}-2,6,11-{Ru(CO)3}-7,11,12-{Ru(CO)3}-3,6,12-(micro-H)3-2,2,7,7,11,11-(CO)6-closo-2,7,11,1-Ru3CB8H6] (1a), which contains a planar Ru6 'raft' supported by a {CB8} monocarborane cluster. Addition of CuCl(PPh3)]4 and TlPF6] to a CH2Cl2 solution of 1a results in simple cation replacement, forming the analogous Cu(PPh3)3]+ salt (1b). The phenyl-substituted monocarborane NEt4]6-Ph-nido-6-CB9H11] reacts with Ru3(CO)12] in refluxing 1,2-dimethoxyethane to afford the pentaruthenium cluster species N(PPh3)2]2,3,7-{Ru(CO)3}-3,4,8-{Ru(CO)3}-7,8-(micro-H)2-1-Ph-2,2,3,3,4,4-(CO)6-hypercloso-2,3,4,1-Ru3CB8H6] (2), after addition of N(PPh3)2]Cl. Treatment of 2 with CuCl(PPh3)]4 and TlPF6] in CH2Cl2 forms the zwitterionic complex 10,12-{exo-Cu(PPh3)2}-2,3,7-{Ru(CO)3}-3,4,8-{Ru(CO)3}-7,8,10,12-(micro-H)4-1-Ph-2,2,3,3,4,4-(CO)6-hypercloso-2,3,4,1-Ru3CB8H4] (3). Substitution of CO by PPh3 with concomitant cation replacement occurs on introduction of AuCl(PPh3)], TlPF6], and PPh3 to a CH2Cl2 solution of 2, forming Au(PPh3)2]2,3,7-{Ru(CO)2PPh3}-3,4,8-{Ru(CO)2PPh3}-7,8-(micro-H)2-1-Ph-2,2,3,3,4,4-(CO)6-hypercloso-2,3,4,1-Ru3CB8H6] (4). Crystallographic studies confirmed the cluster architectures in 1b, 2, and 3.