Heterometalation of 1,1′-Bis(ortho-carborane)

Deboronation of [8-(1'-closo-1',2'-C2B10H11)-closo-2,1,8-MC2B9H10] affords diastereoisomeric mixtures of [8-(7'-nido-7',8'-C2B9H11)-closo-2,1,8-MC2B9H10](-) anions (1, M = Ru(p-cymene); 2, M = CoCp) isolated as [HNMe3](+) salts. Deprotonation of 1 and reaction with CoCl2/NaCp followed by oxidation yields [8-(1'-3'-Cp-closo-3',1',2'-CoC2B9H10)-2-(p-cymene)-closo-2,1,8-RuC2B9H10] isolated as two separable diastereoisomers, namely, 3 alpha and 3 beta, the first examples of heterometalated derivatives of 1,1'-bis(ortho-carborane). Deprotonation of [7-(1'-closo-1',2'-C2B10H11-nido-7,8-C2B9H11](-),metalation with CoCl2/NaCp* and oxidation affords the isomers [1-(1'-closo-1',2'-C2B10H11)-3-Cp*-closo-3,1,2-CoC2B9H10] (4) and [8-(1'-c/=loso-1',2'-C2B10H11)-2-Cp*-closo-2,1,8-CoC2B9H10] (5) as well as a trace amount of the 13-vertex/12-vertex species [12-(1'-closo-1',2'-C2B10H11)-4,5-Cp*(2)-closo-4,5,1,12-Co2C2B9H10] (6). Reduction then reoxidation of 4 converts it to 5. Deboronation of either 4 or 5 yields a diastereoisomeric mixture of [8-(7'-nido-7',8'-C2B9H11)-2-Cp*-closo-2,1,8-CoC2B9H10](-) (7), again isolated as the [HNMe3](+) salt. Deprotonation of this followed by treatment with [RuCl2(p-cymene)](2) produces [8-(1'-3'-(p-cymene)-closo-3',1',2'-RuC2B9F10)-2-Cp*-closo-2,1,8-CoC2B9H10] (8) as a mixture of two diastereoisomers in a 2:1 ratio, which could not be separated. Diastereoisomers 8 are complementary to 3 alpha and 3 beta in which {CoCp} and {Ru(p-cymene)} in 3 were replaced by {Ru(p-cymene)} and {CoCp*}, respectively, in 8. Finally, thermolysis of mixture 8 in refluxing dimethoxyethane yields [8-(8'-2'-(p-cymene)-closo-2',1',8'-RuC2B9H10)-2-Cp*closo-2,1,8-CoC2B9H10] (9), again as a 2:1 diastereoisomeric mixture that could not be separated. All new species were characterized by multinuclear NMR spectroscopy, and 3 alpha, 3 beta, 4, 5, 6, and 9 were also characterized crystallographically.