Ruthenium-Mediated Cyclometalation Reactions of Allene and Allylphosphine CC Bonds: Synthesis of κ(P),η4-(Hexa-2,5-dien-1-yl)diphenylphosphine–Ruthenium(II) Complexes

The cyclopentadienyl-containing complex [Ru(η5-C5H5)(MeCN){κ3(P,C,C)-Ph2PCH2CHCH2}][PF6] (1) reacts with allenes, giving regioselectively the η2-allene complexes [Ru(η5-C5H5)(MeCN){κ(P)-Ph2PCH2CHCH2}(η2-CH2CCR1R2)][PF6] [R1 = R2 = Me (3); R1 = H, R2 = Ph (4); R1R2 = −(CH2)5– (5)]. On the other hand, the reaction of the pentamethylcyclopentadienyl-containing complex [Ru(η5-C5Me5)(MeCN){κ3(P,C,C)-Ph2PCH2CHCH2}][OTf] (2) with allenes yields regio- and stereoselectively the complexes [Ru(η5-C5Me5){κ(P),η4-Ph2PCH2CHCHC(R1R2)CHCH2}][OTf] [R1 = R2 = Me (6); R1 = H, R2 = Ph (7); R1R2 = −(CH2)5– (8)] via the intermolecular coupling of allene and allyldiphenylphosphine ligands. The intermediate complex [Ru(η5-C5Me5)(MeCN){κ(P)-Ph2PCH2CHCH2}{η2-CH2CCMe2}][OTf] (9) has been spectroscopically characterized. The structure of complex [Ru(η5-C5Me5){κ(P),η4-Ph2PCH2CHCHC(Me)2CHCH2}][{3,5-(CF3)2C6H3}4B] (6a) has been resolved by X-ray diffraction analysis.