Synthesis and Properties of (±)- and (+)-4-MeS-3-C2H5-1,2,3-C2CoB9H10

Selective demethylation of the zwitterion 9-Me 2 S-7,8-C 2 B 9 H 11 by sodium naphthalenide in tetrahydrofuran led to the racemic [ 9-MeS-7,8-C 2 B 9 H 11 ] - ion, which could be partially resolved to its (-)-enantiomer via the [(-)-1-Ph-1-Me 3 N-CHCH 3 ] + salt. Complexation of the ions with Co 2+ and C 5 H 5 - afforded the (±)- and (+)-4-MeS-3-C 2 H 5 -1,2,3-C 2 CoB 9 H 10 cobaltacarboranes, respectively. A partially resolved (-)-9-Me 2 S-7,8-C 2 B 9 H 11 was obtained by re-methylation of the (-)-[ 9-MeS-7,8-C 2 B 9 H 11 ] - ion.