Reactivity studies of highly electrophilic ruthenium complexes

摘要

The 16-electron, coordinatively unsaturated, dicationic ruthenium complex [Ru(P(OH)_2(OMe))(dppe)_2][OTf]_2 (1a) brings about the heterolysis of the C-H bond in phenylacetylene to afford the phenylacetylide complex trans-[Ru(CCPh)(P(OH)_2(OMe))(dppe) _2][OTf] (2). The phenylacetylide complex undergoes hydrogenation to give a ruthenium hydride complex trans-[Ru(H)(P(OH)_2(OMe))(dppe) _2][OTf] (3) and phenylacetylene via the addition of H_2 across the Ru-C bond. The 16-electron complex also reacts with HSiCl_3 quite vigorously to yield a chloride complex trans-[Ru(Cl)(P(OH) _2(OMe))(dppe)_2][OTf] (4). On the other hand, the other coordinatively unsaturated ruthenium complex [Ru(P(OH)_3)(dppe) _2][OTf]_2 (1b) reacts with a base N-benzylideneaniline to afford a phosphonate complex [Ru(P(O)(OH)_2)(dppe)_2][OTf] (5) via the abstraction of one of the protons of the P(OH)_3 ligand by the base. The phenylacetylide, chloride, and the phosphonate complexes have been structurally characterized. The phosphonate complex reacts with H _2 to afford the corresponding dihydrogen complex trans- [Ru(η~2-H_2)(P(O)(OH)_2)(dppe) _2][OTf] (5-H_2). The intact nature of the H-H bond in this species was established using variable temperature ~1H spin-lattice relaxation time measurements and the observation of a significant J(H,D) coupling in the HD isotopomer trans-[Ru(η~2-HD)(P(O)(OH) _2)(dppe)_2][OTf] (5-HD).