First Bis(allenylidene)diruthenium Derivatives [(Ph3P)4(μ-Cl)3Ru2(CCCAr2)2]PF6 and Access to [(Ph2PCH2CH2PPh2)2ClRu(CCCAr2)]PF6 Complexes

RuCl 2 (PPh 3 ) 3 reacts with HC⋮CC(OH)Ar 2 derivatives in the presence of NaPF 6 to selectively afford only one isomer of the cationic bis(allenylidene) binuclear complexes [(Ph 3 P) 4 (μ-Cl) 3 Ru 2 ( C C CAr 2 ) 2 ]PF 6 [ 3; Ar = C 6 H 5 ( a ), p -C 6 H 4 Cl ( b ), p -C 6 H 4 F ( c )]. Complex 3a on treatment with an excess of Ph 2 PCH 2 CH 2 PPh 2 (dppe) gives access to the new mononuclear complex trans -[(dppe) 2 ClRu( C C CAr 2 )]PF 6 ( 4a ). The direct reaction of cis -RuCl 2 (dppe) 2 with the alcohols HC⋮CC(OH)Ar 2 and NaPF 6 also readily gives the allenylidene complexes 4a − c .