Reactivity of {Ru(C 5 Me 5 )[η 2 ‐ P , O ‐Ph 2 PCH 2 C( t Bu)=O](CO)}[PF 6 ] towards Terminal Alkynes and Unexpected Rearrangement of a Fischer‐Type Carbene Ligand

The ruthenium complex {Ru(C 5 Me 5 )[η 2 ‐ P , O ‐Ph 2 PCH 2 C( t Bu)=O](CO)}[PF 6 ] reacts with terminal alkynes HC≡CR (R = H, t Bu, Ph) in methanol to afford {Ru[ : C(OMe)CH 2 R](C 5 Me 5 )[η 1 ‐ P ‐Ph 2 PCH 2 C(=O) t Bu](CO)}[PF 6 ] derivatives. The similar reaction conducted in dichloromethane as solvent led to six‐membered metallacyclic complexes{Ru(C 5 Me 5 )[η 2 ‐ C,P ‐ : C(CH 2 R)OC( t Bu)=CH–PPh 2 ](CO)}[PF 6 ], which, when R is an aromatic group (R = Ph, p ‐tolyl), rearrange under moderate thermal activation into {Ru(C 5 Me 5 )[η 3 ‐ C , C , P ‐RCH=CH‐OC( t Bu)=CHPPh 2 ](CO)}[PF 6 ] derivatives, according to an isomerization of a Fischer‐type carbene ligand into an η 2 ‐coordinated vinylic ether, as shown by X‐ray single crystal analysis (R = p ‐tolyl).(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)