Reactivity of {Ru(C₅Me₅)[η²‐P,O‐Ph₂PCH₂C(tBu)=O](CO)}[PF₆] towards Terminal Alkynes and Unexpected Rearrangement of a Fischer‐Type Carbene Ligand

Abstract

The ruthenium complex {Ru(C5Me5)[η2‐P,O‐Ph2PCH2C(tBu)=O](CO)}[PF6] reacts with terminal alkynes HC≡CR (R = H, tBu, Ph) in methanol to afford {Ru[:C(OMe)CH2R](C5Me5)[η1‐P‐Ph2PCH2C(=O)tBu](CO)}[PF6] derivatives. The similar reaction conducted in dichloromethane as solvent led to six‐membered metallacyclic complexes{Ru(C5Me5)[η2‐C,P‐:C(CH2R)OC(tBu)=CH–PPh2](CO)}[PF6], which, when R is an aromatic group (R = Ph, p‐tolyl), rearrange under moderate thermal activation into {Ru(C5Me5)[η3‐C,C,P‐RCH=CH‐OC(tBu)=CHPPh2](CO)}[PF6] derivatives, according to an isomerization of a Fischer‐type carbene ligand into an η2‐coordinated vinylic ether, as shown by X‐ray single crystal analysis (R = p‐tolyl).(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)