Chemistry on the Rhodacarborane Cluster [9,9-(PPh3)-nido-9,7,8-RhC2B8H11]: Formation of Bidentate Phosphine and Bimetallic Derivatives
The electronically unsaturated rhodacarborane [9,9-(PPh 3 ) 2 - nido -9,7,8-RhC 2 B 8 H 11 ] ( 1 ), reacts with Ph 2 PCH 2 PPh 2 (dppm) to afford [9,9-(dppm-κ 2 P )-9-(dppm-κ P )- nido -9,7,8-RhC 2 B 8 H 11 ] ( 3 ), in which the Rh-bonded PPh 3 ligands have been replaced by two dppm ligands, one in a bidentate mode and the second in a unidentate mode with a free PPh 2 end. The structure of 3 is similar to the related, and isoelectronic, species [8,8-(dppm-κ 2 P )-8-(dppm-κ P )- nido -8,7-RhSB 9 H 10 ] ( 4 ), but with a difference in the orientation of the ligands. Reaction of 1 with Ph 2 P(CH 2 ) 2 PPh 2 (dppe) affords a species tentatively identified as [9,9-(dppe-κ 2 P )-9-(dppe-κ P )- nido -9,7,8-RhC 2 B 8 H 11 ] ( 5 ). If allowed to react with [Ru(η 6 - p -cym)Cl 2 ] 2, ( 3 ) affords [9,9-{Ru(η 6 - p -cym)dppm-κ 2 P -(μ-Cl) 2 }- nido -9,7,8-RhC 2 B 8 H 11 ] ( 6 ) containing the group [(μ-Cl) 2 Ru(η 6 - p -cym)dppm] that coordinates in a multidentate mode to Rh. Compounds 3 and 6 are characterized by 11 B, 1 H and 31 P NMR spectroscopy, elemental analysis and X-ray structure determinations.