Hybrid diborolyl/carbaboranyl triple-decker compounds: [(η5-pentamethylcyclopentdienyl)ruthenium(μ,η5-1,3-diborolyl)rhodiumcarbaboranyl] complexes

Reaction of the violet sandwich [(η5-C5Me5)Ru{η5-(CMe)2(BMe)2(CMe)}] with [(C2H4)2RhCl]2 generates the tetranuclear complex [(η5-C5Me5)Ru{μ,η5-(CMe)2(BMe)2(CMe)}RhCl]2 (7). Treatment of 7 with the nido-2,3-Et2C2B4H51− anion leads to the violet air-sensitive triple decker complex [(η5-C5Me5)Ru{μ,η5-(CMe)2(BMe)2(CMe)}Rh(η5-2,3-Et2C2B4H5) (8), in which the neutral carborane functions as a 5e donor. Its structure is derived from 1H-, 11B-, 13C-NMR and mass spectral data. The green paramagnetic triple-decker [(η5-C5Me5)Ru{μ,η5-(CMe)2(BMe)2(CMe)}Rh(C2B9H11)] (9) is obtained from the nido-7,8-C2B9H121− carboranyl anion and 7. Reaction of 7 with the nido-6-Me-5,6,9-C3B7H91− anion yields the green, air-stable triple-decker complexes [(η5-C5Me5)Ru{μ,η5-(CMe)2(BMe)2(CMe)}Rh(2-Me-2,3,4-C3B7H9)] (10a) and [(η5-C5Me5)Ru{μ,η5-(CMe)2(BMe)2(CMe)}Rh(4-Me-2,3,4-C3B7H9)] (10b) having 30 valence electrons. An X-ray structure analysis of 10a confirms the expected octadecahedral geometry for the closo-RhC3B7 cluster framework.