Penta- and Hexaruthenium Carbonyl ‘Raft' Complexes Supported by Monocarborane Cage Ligands

Reaction between [PPh4][closo-4-CB 8 H 9 ] 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-(μ-H)3-2,2,7,7,11,11-(CO) 6 -closo-2,7,11,1-Ru 3 CB 8 H 6 ] (1a), which contains a planar Ru 6 'raft' supported by a {CB 8 } monocarborane cluster. Addition of [CuCl(PPh 3 )] 4 and TI[PF 6 ] to a CH 2 Cl 2 solution of 1a results in simple cation replacement, forming the analogous [Cu(PPh 3 ) 3 ] + salt (1b). The phenyl-substituted monocarborane [NEt4][6-Ph-nido-6-CB 9 H 11 ] reacts with [Ru 3 (CO) 12 ] in refluxing 1,2-dimethoxyethane to afford the pentaruthenium cluster species [N(PPh 3 ) 2 ]-[2,3,7-{Ru(CO)3}-3,4,8-{Ru(CO)3}-7,8-(μ-H)2-1-Ph-2,2,3,3,4,4-(CO)6-hypercloso-2,3,4,1-Ru 3 CB 8 H 6 ] (2), after addition of [N(PPh 3 )2]Cl. Treatment of 2 with [CuCl(PPh 3 )] 4 and TI[PF 6 ] in CH 2 Cl 2 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-(μ-H)4-1-Ph-2,2,3,3,4,4-(CO)6-hyperctoso-2,3,4,1-Ru 3 -CB 8 H 4 ] (3). Substitution of CO by PPh 3 with concomitant cation replacement occurs on introduction of [Aucl(PPh 3 )], Tl[PF 6 ], and PPh 3 to a CH 2 Cl 2 solution of 2, forming [Au(PPh3)2][2,3,7-{Ru(CO)2PPh3}-3,4,8-{Ru(CO)2PPh3}-7,8-(μ-H)2-1-Ph-2,2,3,3,4,4-(CO)6-hyperc/oso-2,3,4,1-Ru 3 CB 8 H 6 ] (4). Crystallographic studies confirmed the cluster architectures in 1b, 2, and 3.