Enolate‐Phosphane Ligands Providing a Tool for the Selective Substitution of Triphenylphosphane by Carbon Monoxide or Trimethylphosphane in Complex {Ru(Cp)[η 2 ‐ P , O ‐Ph 2 PCH 2 C( t Bu)=O](PPh 3 )}[PF 6 ], and Subsequent Reactivity Towards Terminal Alkynes

The deprotonation under basic conditions of the keto‐phosphane ligand in complexes {Ru(Cp)[η 1 ‐ P ‐Ph 2 PCH 2 C(=O) t Bu](PPh 3 )(L)}[PF 6 ] (L = CO or PMe 3 ) that arise from the addition of L to {Ru(Cp)[η 2 ‐ P , O ‐Ph 2 PCH 2 C( t Bu)=O](PPh 3 )}[PF 6 ] generates {Ru + (Cp)[η 1 ‐ P ‐Ph 2 PCH=C( t Bu)O – ](PPh 3 )(L)} zwitterionic species, as shown by an X‐ray crystal structure determination (L = CO). The removal of the triphenylphosphane ligand is subsequently achieved under thermal activation to afford the neutral derivatives Ru(Cp)[η 2 ‐ P , O ‐Ph 2 PCH=C( t Bu)O](L). A further protonation step is sufficient to complete the formation of the new complex {Ru(Cp)[η 2 ‐ P , O ‐Ph 2 PCH 2 C( t Bu)=O](PMe 3 )}[PF 6 ], which reacts in methanolat reflux with 1,1‐diphenyl‐2‐propyn‐1‐ol to afford thesix‐membered metallacyclic derivative {Ru(Cp)[η 2 ‐ C , P :C(CH=CPh 2 )OC( t Bu)=CH–PPh 2 ](PMe 3 )}[PF 6 ], as shown by an X‐ray single crystal analysis. The synthesis of related η 5 ‐indenyl ruthenium complexes and of {Ru(Cp)(=C=CH 2 )[Ph 2 PCH 2 C(=O) t Bu](PR 3 )}[PF 6 ] (PR 3 = PPh 3 or PMe 3 ) vinylidene complexes is also reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)