Sulfur, tin and gold derivatives of 1-(2 '-pyridyl)-ortho-carborane, 1-R-2-X-1,2-C2B10H10(R=2 '-pyridyl, X = SH, SnMe3 or AuPPh3)

Reaction of the lithium salt of 1-(2'-pyridyl)-ortho-carborane, Li[1-R-1,2-C2B10H10] (R= 2'-NC5H4), with sulfur, followed by hydrolysis, gave the mercapto-o-carborane, 1-R-2-SH- 1,2-C2B10H10 which forms chiral crystals containing helical chains of molecules linked by intermolecular S-H...N hydrogen bonds. The cage C(1) - C(2) and exo C(2) -S bond lengths (1.730(3) and 1.775(2) Angstrom, respectively) are indicative of exo S=C pi bonding. The tin derivative 1-R-2-SnMe3-1,2-C2B10H10, prepared from Li[1-R-1,2-C2B10H10] and Me3SnCl, crystallises with no significant intermolecular interactions. The pyridyl group lies in the C(1) - C(2) - Sn plane, oriented to minimise the N ... Sn distance (2.861(3) Angstrom). The tin environment is distorted trigonal bipyramidal with axial N and Me. The gold derivative 1-R-2-AuPPh3-1,2-C2B10H10, prepared from Li[1-R-1,2-C2B10H10] and AuCl(PPh3), reveals no N...Au interaction in its crystal structure.