AGOSTIC B-H-]RU BONDS IN EXO-MONOPHOSPHINO-7,8-DICARBA-NIDO-UNDECABORATE DERIVATIVES

The reaction of [NMe(4)][7-PPh(2)-8-Me-7,8-C2B9H10] with RUCl(3) . H2O or RuCl2(DMSO)(4) leads to the formation of [Ru(7-PPh(2)-8-Me-7,8-C2B 9H10)(2)]. Each carborane ligand is tridentate, forming one P-Ru bond and two B-H-Ru agostic bonds. The number of isomers obtained depends o n the initial ruthenium form, giving one isomer (1) when RuCl3 . H2O i s used and two isomers (1 and 2) in the case of the DMSO derivative. N o reaction is found with similar thiocarborane ligands [NMe(4)][7-SR-8 -Me-7,8-C2B9H10] (R = Ph,Me), suggesting that the surrounding P-2(BH)( 4) is a better stabilizing system. The complexes have been characteriz ed by an X-ray diffraction study.