Metallacumulenes: preparation of novel alkenyl–allenylidene– and diynyl–ruthenium complexes. Crystal structure of a Ru–CC–CC–C(OSiMe₃)Ph₂derivative

Complexes (η6-arene)(PR3)RuCl21 react with HCC–CC–CPh2OX derivatives (X = H, SiMe3) to afford, in alcohol or in the presence of HNPh2, 3-alkenyl allenylidene complexes [(η6-arene)(PR3)ClRuCCC(Y)CHCPh2]+(Y = OEt 4a, OPri5a, NPh26) and diynyl–ruthenium derivatives in the presence of HNPri2.