An Easy Entry to Dimers [{RuX(μ-X)(CO)(P⌒P)}2] (X = Cl, Br; P⌒P = 1,1‘-Bis(diphenylphosphino)ferrocene, 1,1‘-Bis(diisopropylphosphino)ferrocene) from η3-Allylruthenium(II) Derivatives [RuX(η3-2-C3H4R)(CO)(P⌒P)] (R = H, Me): Efficient Catalyst Precursors in Transfer Hydrogenation of Ketones

Complexes [RuX(η 3 -2-C 3 H 4 R)(CO)(P⌒P)] (X = Cl, Br; R = H, Me; P⌒P = dppf, dippf) ( 2a − d and 3a − d ) have been prepared by reaction of the η 3 -allylruthenium(II) derivatives [RuX(η 3 -2-C 3 H 4 R)(CO) 3 ] ( 1a − d ) with 1 equiv of the appropriate diphosphine. Treatment of 2a − d and 3a − d with HX allows the high-yield preparation of the dimeric compounds [{RuX(μ-X)(CO)(P⌒P)} 2 ] (P⌒P = dppf, X = Cl ( 4a ), Br ( 4b ); P⌒P = dippf, X = Cl ( 5a ), Br ( 5b )). Complex [{RuCl(μ-Cl)(CO)(dppf)} 2 ] reacts with neutral ligands, via chloride bridge cleavage, affording the mononuclear derivatives [RuCl 2 (CO)(L)(dppf)] (L = CO ( 6a ), BzNC ( 6b ), Py ( 6c ), PhNH 2 ( 6d )). The structures of compounds [RuCl(η 3 -C 3 H 5 )(CO)(dppf)] ( 2a ), [{RuCl(μ-Cl)(CO)(dppf)} 2 ] ( 4a ), and [RuCl 2 (CO)(Py)(dppf)] ( 6c ) have been confirmed by X-ray crystallography. The catalytic activity of dimers 4a, b and 5a, b in transfer hydrogenation of ketones by propan-2-ol has also been studied.