Binuclear Carbyne and Ketenyl Derivatives of the Alkyl-Bridged Complexes [Mo2(η5-C5H5)2(μ-CH2R)(μ-PCy2)(CO)2] (R = H, Ph)
摘要:
The 30-electron benzylidyne complex [Mo2Cp2(mu-CPh)(mu-PCy2)(mu-CO)] (Cp = eta(5)-C5H5) could be conveniently prepared upon photolysis of the benzyl-bridged complex [Mo2Cp2(mu-CH2Ph)(mu-PCy2)(CO)(2)]. It reacted with CO to give the ketenyl complex [Mo2Cp2{mu-C(Ph)CO}(mu-PCy2)(CO)(2)] (2.6101(2) angstrom), which in turn could be selectively decarbonylated at 353 K to give the 32-electron benzylidyne derivative [Mo2Cp2(mu-CPh)(mu-PCy2)(CO)(2)] (Mo-Mo = 2.666(1) angstrom). Related methylidyne complexes could be obtained from the methyl-bridged complex [Mo2Cp2(mu-CH3)(mu-PCy2)(CO)(2)] via its trinuclear derivative [Mo3Cp2(mu(3)-CH)(mu-PCy2)(CO)(7)] Thus, the carbonylation of the latter cluster gave the ketenyl complex [Mo2Cp2{mu-C(H)CO}(mu-PCy2)(CO)(2)], whereas its reaction with P(OMe)(3) gave the substituted cluster [Mo3Cp2(mu(3)-CH)(mu-PCy2)(CO)(6){P(OMe)(3)}], which in turn could be thermally degraded to give selectively the 30-electron methylidyne derivative [Mo2Cp2(mu-CH)(mu-PCy2)(mu-CO)] (Mo-Mo = 2.467(1) angstrom). DFT calculations on the phenylketenyl complex revealed that the metal ligand interaction is intermediate between the extreme descriptions represented by the acylium (3-electron donor) and ketenyl (1-electron donor) canonical forms of this ligand.
Reactivity of the α-Agostic Methyl Bridge in the Unsaturated Complex [Mo<sub>2</sub>(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)<sub>2</sub>(μ-η<sup>1</sup>:η<sup>2</sup>-CH<sub>3</sub>)(μ-PCy<sub>2</sub>)(CO)<sub>2</sub>]: Migratory Behavior and Methylidyne Derivatives
作者:M. Angeles Alvarez、Daniel García-Vivó、M. Esther García、M. Eugenia Martínez、Alberto Ramos、Miguel A. Ruiz
DOI:10.1021/om800061z
日期:2008.5.1
The bridging methyl ligand present in the title compound can migrate up to the cyclopentadienyl (Cp) site upon reaction with CO to achieve an overall exchange between the methyl and hydrogen (Cp) positions. In the presence of different metal-carbonyl complexes, easy dehydrogenation of the methyl group takes place under photochemical conditions to give methylidyne-bridged heterometallic clusters.