Chain extension and C-C bond formation on C-4 polycarbon ligands: Novel chemistry of sigma-pi-butadiynyl complexes with carbene sources

Reaction of Ru-2(CO)(6)(mu-eta(1):eta(2) (alpha,beta)-C=CC=CR)-(mu-PPh(2)) (1a, R=Bu(t); 1b, R=Ph) with the carbene precursors R'2CN2 (R'=H, Ph) affords the 1-ynyl-allenyl complexes Ru-2(CO)(6)(mu-eta(1):eta(2) (alpha,beta)-C(C=CR)=C=CR'(2))-(mu-PPh(2)) (2a, R=Bu(t), R'=Ph; 2b, R=Ph, R'=H; 2c, R=R'=Ph) via attack of the carbene group at C-alpha of the butadiynyl ligand. In the case of Ph(2)CN(2), carbene addition also occurs at C-beta to give the eta(1)-indenyl derivatives Ru-2(CO)(6){mu-eta(1):eta(2)-CH(C6H4)C(Ph)=CC=CBu(t)}(mu-PPh(2)) (3) or Ru-2(CO)(6){mu-eta(1):eta(2)-C=C(Ph)C=C(Ph)(C6H4)-CH}(mu-PPh(2)) (4) via two carbon-carbon bond-forming processes. The molecular structures of 2a, 3, and 4 have been, determined by X-ray crystallography.