New reaction pathways for mu-eta(1),eta(2)-allenyl ligands: On-off allenyl coordination and CO insertion into the hydrocarbyl bridge in Ru-2(CO)(6)(mu-PPh(2)){mu-eta(1),eta(2)alpha,beta-C(Ph)=C=CP2}

The binuclear allenyl complex Ru-2(CO)(6)(mu-PPh(2)){mu-eta(1),eta(alpha,beta)(2)-C(Ph)=C=CPh(2)} (1) reacts with bis(diphenylphosphino)methane (dppm) to afford Ru-2(CO)(4)(mu-PPh(2))(mu-dppm){mu-eta(1),eta(2)-C(O)C(Ph)=C=CPh2} (2) containing an acylallenyl ligand and Ru-2(CO)(4)(mu-PPh(2))(mu-dppm){mu(2)-eta(1),eta(alpha,beta)(2)-C(Ph)=C=CPh(2)} (4). With bis(diphenylphosphino)ethane (dppe), 1 affords Bu(2)(CO)(5)(mu-PPh(2))(eta(2)-dppe){eta(1)-C(Ph)=C=CPh(2)} (3), which contains a terminal eta(1)-coordinated allenyl fragment. The X-ray structures of 2-4 are reported.