Reactivity of the Unsaturated Complex [(C6Me6)2Ru2(μ2-H)3]+toward Phosphines: Synthesis and Molecular Structure of the Dinuclear Cations [(C6Me6)2Ru2(μ2-PR2)(μ2-H)2]+and Characterization of the P−C Bond Activation Intermediate [(C6Me6)2Ru2(μ2-PPh2)(μ2-H)(μ2-Ph)]+

The unsaturated trihydrido complex [(C 6 Me 6 ) 2 Ru 2 (μ 2 -H) 3 ] + reacts with diaryl- or dialkylphosphines PR 2 H to give the dinuclear cations [(C 6 Me 6 ) 2 Ru 2 (μ 2 -PR 2 )(μ 2 -H) 2 ] + (R= Ph, 1; R = t -Bu, 2 ). Surprisingly, complexes of the type [(C 6 Me 6 ) 2 Ru 2 (μ 2 -PR 2 )(μ 2 -H) 2 ] + with R = Ph ( 1 ), n -Bu ( 3 ), n -Oct ( 4 ) are also accessible in high yield from the reaction of [(C 6 Me 6 ) 2 Ru 2 (μ 2 -H) 3 ] + with the corresponding triaryl- or trialkylphosphine PPh 3, P( n -Bu) 3, or P( n -Oct) 3 by carbon−phosphorus bond cleavage. A possible intermediate of the reaction with PPh 3, [(C 6 Me 6 ) 2 Ru 2 (μ 2 -PPh 2 )(μ 2 -H)(μ 2 -Ph)] + ( 5 ), could be isolated from the reaction mixture as the tetrafluoroborate salt, the single-crystal X-ray structure analysis of which reveals a bridging phenyl ligand coordinated in an η 1 -μ 2 fashion to the diruthenium backbone. With the mixed phosphine PMe 2 Ph, [(C 6 Me 6 ) 2 Ru 2 (μ 2 -H) 3 ] + reacts to give [(C 6 Me 6 ) 2 Ru 2 (μ 2 -PMe 2 )(μ 2 -H) 2 ] + ( 6 ) and the corresponding intermediate [(C 6 Me 6 ) 2 Ru 2 (μ 2 -PMe 2 )(μ 2 -H)(μ 2 -Ph)] + ( 7 ). All dinuclear cations are isolated as the tetrafluoroborate salts.