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

Reaction between [PPh4][closo-4-CB8H9] and [Ru-3(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-(mu-H)(3)-2,2,7,7,11,11-(CO)(6)-closo-2,7,11,1-Ru3CB8H6] (1a), which contains a planar Ru-6 'raft' supported by a {CB8} monocarborane cluster. Addition of [CuCl(PPh3)](4) and Tl[PF6] 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 [Ru-3(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-(mu-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 Tl[PF6] 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-(mu-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)], Tl[PF6], and PPh3 to a CH2Cl2 solution of 2, forming [Au(PPh3)(2)][2,3,7-{Ru(CO)(2)PPh3}-3,4,8-{Ru(CO)(2)PPh3}-7,8-(mu-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.