Regioselective Synthesis of η⁴-Dienylphosphane Ruthenium Complexes by Oxidative Coupling Reactions

Complexes [Ru(η5-C5H5){κ3(P,C,C)-Ph2P(CH2)nCHCH2}(MeCN)][PF6] (n = 1 (1), 2 (2)) react with C⋮C bonds of propargylic alcohols to yield regioselectively the complexes [Ru(η5-C5H5){κ(P),η4-Ph2P(CH2)nCHCHC(R)CH2}][PF6] (n = 1, R = CPh2OH (3), C(C12H8)OH (4), C(C4H8)OH (5), CMePhOH (6a, 6b); n = 2, R = CPh2OH (7), C(C4H8)OH (8), CMePhOH (9a, 9b), CHPhOH (10a, 10b)). The reaction of complex 1 with terminal alkynes also leads regioselectively to the complexes [Ru(η5-C5H5){κ(P),η4-(2Z,4E)-Ph2PCH2CHCHCHCH(R)}][PF6] (R = Ph (11), p-MeC6H4 (12)). Single-crystal X-ray diffraction analyses for complexes 9a, 9b, 10b, and 12 have been carried out and allow the unambiguous assignment of the stereochemistry of the complexes. DFT calculations regarding the thermodynamic stability of the obtained products have also been performed.