Synthesis and X-ray Structural Characterization of Ru(PPh3)3(CO)(C2H4) and RuH(o-C6H4C(O)CH3)(PPh3)2L (L = PPh3, CO, DMSO): Ruthenium Complexes with Relevance to the Murai Reaction

Abstract

The ruthenium complexes Ru(PPh3)3(CO)(C2H4) (1) and RuH(o-C6H4C(O)CH3)(L)(PPh3)2 (2, L = PPh3; 3, L = CO; 4, L = DMSO) have been prepared in order to assess their activity for catalyzing the insertion of alkenes into the ortho C−H bond of aromatic ketones (Murai reaction). Treatment of RuH2(CO)(PPh3)3 with ethene in refluxing toluene afforded 1, which has been characterized by multinuclear NMR spectroscopy and X-ray crystallography. Excess acetophenone reacted with Ru(H2)H2(PPh3)3 to give RuH(o-C6H4C(O)CH3)(PPh3)3 (2), which loses triphenylphosphine upon addition of CO or DMSO to give RuH(o-C6H4C(O)CH3)(CO)(PPh3)2 (3) and RuH(o-C6H4C(O)CH3)(DMSO)(PPh3)2 (4), respectively. The X-ray crystal structures of both of these compounds have been determined. The activity for catalyzing the reaction of 2‘-methylacetophenone with triethoxyvinylsilane follows the order RuH2(CO)(PPh3)3 > 2 > 1 > 4. Complex 3, along with both RuH2(CO)(AsPh3)3 and RuH2(CO)(dppp)(PPh3) (dppp = Ph2P(CH2)3PPh2), show essentially zero cataly...