In the title compound, (eta (5)-2,5-dimethylpyrrolyl)[(7,8,9,10,11-eta)-7-m
ethyl-7,8-dicarba-nido-undecaborato]cobalt(III), [3-Co{eta (5)-[2,5-(CH3)(2
)-NC4H2]}-1-CH3-1,2-C2B9H10] or [Co(C3H13B9)(C6H8N)], the Co-III atom is sa
ndwiched between the pentagonal faces of the pyrrolyl and dicarbollide liga
nds, resulting in a neutral molecule. The C-C distance in the dicarbollide
cage is 1.649 (3) Angstrom.