Starke metallorganische Lewissäuren: Tricarbonyl-π-cyclopentadienylkationen von Molybdän und Wolfram [(π-C5H5 )(OC)3M]+⊕(M = Mo, W)/Strong Organometallic Lewis Acids: Tricarbonyl-π-cyclopentadienyl Cations of Molybdenum and Tungsten [(π-C5H5)(OC)3M]+ (M = Mo, W)

Abstract

Hydride abstraction from the hydrides (π-C5H5)(OC)3MH (M = Mo, W) using Ph3C+X_ (X = BF4, PF6) affords the compounds (π-C5H5)(OC)3MX in high yields. IR data indicate that in these complexes tetrafluoroborate and hexafluorophosphate are coordinated to the metal. The complexes behave as strong Lewis acids; they react with σ- and π-donors L to give [(π-C5H5)(OC)3ML]+X- [L = CO, PPh3, PCl3, C2H4, CH3CN, H2O, (CH3)2CO, C4H8O(THF)]. The hexafluorophosphate compounds add methylene chloride to give [(π-C5H5)(OC)3M(CH2Cl2)]+PF6 -. Reaction with diphenylacetylene yields [(π-C5H5)(OC)M(PhC ≡CPh)2]+BF4- (M = Mo, W). The hydride-bridged complexes {[(π-C5H5)M(CO)3]2H}+X- have been obtained by reaction of (π-C5H5)(OC)3MX with (π-C5H5)(OC)3MH.