Alkyl, alkynyl, and olefin complexes of bis(π-cyclopentadienyl)-molybdenum or -tungsten : a reversible metal-to-ring transfer of an ethyl group

Abstract

The compounds [(π-C5H5)2M(CH2CHR)H]+PF6– where M = Mo, W, R = H; M = W, R = Me, (π-C5H5)2M(C2H4), (π-C5H5)2MoEtCl, (π-C5H5)2MMe2, (π-C5H5)2M(CCPh)2 have been prepared and studied. The reversible reaction [(π-C5H5)2M(CH2CHR)H]+→ H++(π-C5H5)2MCH2CHR has been demonstrated. With tertiary phosphines the ethyl complex gives the endo-ethyl derivatives (π-C5H5)(1 -endo-EtC5H5)MoPR3Cl. The complex (π-C5H5)(1 -endo-EtC5H5)MoPClMe2Ph reacts with thallium tetrafluoroborate to give the ethyl cation [(π-C5H5)2MoPR3Et]+BF4–. This and related cations may also be prepared from the hydridoethylene cations and tertiary phosphine. Mechanisms for these reactions are discussed.