Metallacumulenes: new allenylidene–ruthenium complexes. Crystal structure of a cationic [(Ph 2 PCH 2 PPh 2 ) 2 (Cl)RuCCCR 1 R 2 ] + derivative

The activation with cis-RuCl2(Ph2PCH2PPh2)21 of HCC–CR2OH and HCC–C(Me)CH2 leads to allenylidenes trans-(Cl)Ru+CCCR2(Ph2PCH2PPh2)2(R = Ph, Me, p-Cl-Ph) and that of HCC–CC–CPh2OSiMe3 affords a new allenylidene–ruthenium complex 9via an intramolecular ortho C–H bond addition.