Reactions of benzophenone imine complex [Tp(NH═CPh2)(PPh3)Ru–Cl] with alkyne and dimerization of terminal alkynes in the presence of Et3N

Treatment of benzophenone imine complex [Tp(PPh3)(NH═CPh2)Ru–Cl] (1) {Tp═HB(pz)3, pz = pyrazolyl} with 4-Ethynyltoluene in the presence of H2O in distilled ethanol afforded the chelate alkenyl ketone complex [Tp(PPh3)RuCCH2(p-MeC6H4)═CHC(O)(p-MeC6H4)] (2). On the other hand, reaction of 1 with HC≡C(O)OR1 in R2OH produced the chelate vinyl ether complexes [Tp(PPh3)Ru–C(OR2)═CHC(O)OR1] (3a, R1 = Me, R2 = Me; 3b, R1 = Et, R2 = Me; 3c, R1 = Et, R2 = Et; 3d, R1 = Me, R2 = Et), respectively. Preliminary results on the catalytic activity of 1 are also presented. Intriguingly, complex 1 is found to catalyze the dimerization of terminal alkynes HC≡CR (R = p-MeC6H4, C(O)OCH3) in the presence of Et3N to give eynes. The structures of 3c and 3d have been determined by X-ray diffraction analysis.