Hydride, alkyl and carbyne derivatives of the unsaturated heterometallic anion [MoWCp2(μ-PCy2)(μ-CO)2]−

Publication date: Available online 30 April 2019Source: Journal of Organometallic ChemistryAuthor(s): M. Angeles Alvarez, M. Esther García, Daniel García-Vivó, Estefanía Huergo, Miguel A. RuizAbstractThe heterometallic hydride [MoWCp2(μ-H)(μ-PCy2)(CO)4] was prepared in 30% yield through reaction of an equimolar mixture of [Mo2Cp2(CO)6] and [W2Cp2(CO)6] with a two-fold excess of PHCy2 in xylene solution, in a sealed tube at 453 K. The sodium salt of the title anion was then prepared from the latter hydride in a three-step process first involving dehydrogenation with HBF4·OEt2 in dichloromethane to give the cationic derivative [MoWCp2(μ-PCy2)(CO)4](BF4), then reaction of the latter with NaI in refluxing 1,2-dichloroethane to yield the iodide-bridged dicarbonyl complex [MoWCp2(μ-I)(μ-PCy2)(CO)2] and, finally, reaction of the latter with Na(Hg) in tetrahydrofuran solution. Reaction of this anion with (NH4)PF6 gave the hydride [MoWCp2(H)(μ-PCy2)(CO)2], which in solution displays an equilibrium mixture of two isomers, one with terminal carbonyls and the hydride ligand bridging the metal atoms (B), another one with a semibridging carbonyl and the hydride ligand terminally bound to the W atom (T). The prevalence of isomer T was higher than the observed ones in the corresponding homometallic analogues, and there was a clear thermodynamic preference of the hydride ligand for the W site, estimated in some 20 kJ/mol according to density functional theory (DFT) calculations...
Source: Journal of Organometallic Chemistry - Category: Chemistry Source Type: research