Usage of (C 5 R 5 )Co(CO)I 2 (R = H, Me) for the synthesis of 12-vertex closo -cobaltacarboranes. Unexpected formation of 10-{CpCo(C 5 H 4 )}-7,8-Me 2 -7,8- nido -C 2 B 9 H 9

Abstract A series of 12-vertex closo -cobaltacarboranes 1,2-Rʹ 2 -3-(C 5 R 5 )-3,1,2-CoC 2 B 9 H 9 ( 1a : R = Rʹ = H; 1b : R = Me, Rʹ = H; 2a : R = H, Rʹ = Me; 2b : R = Rʹ = Me) were synthesized by reactions of the carbonyl cobalt complexes (C 5 R 5 )Co(CO)I 2 with Tl[Tl(η-7,8-Rʹ 2 -7,8-C 2 B 9 H 9 )]. The reaction of CpCo(CO)I 2 with Tl[Tl(η-7,8-Me 2 -7,8-C 2 B 9 H 9 )] is accompanied by side formation of the novel charge-compensated nido -carborane 10-{CpCo(C 5 H 4 )}-7,8-Me 2 -7,8- nido -C 2 B 9 H 9 ( 3 ) in 19% yield. The structures of 2a , b and 3 were determined by X-ray diffraction.