960069-53-8Relevant articles and documents
Chemistry of unsaturated group 6 metal complexes with bridging hydroxy- and methoxycarbyne ligands. 2. Synthesis, structure, and bonding of 32- and 34-electron complexes
Garcia, M. Esther,Garcia-Vivo, Daniel,Ruiz, Miguel A.,Alvarez, Santiago,Aullon, Gabriel
, p. 5912 - 5921 (2008/10/09)
The reaction of the 30-electron methoxycarbyne complex [Mo 2Cp2(μ-COMe)(μ-PCy2)(μ-CO)] with carbon monoxide gives quantitatively the electron-precise derivative [Mo 2Cp2(μ-COMe)(μ-PCy2)(CO)3], in which the methoxycarbyne ligand adopts a highly asymmetric semibridging coordination mode. This tricarbonyl species dissociates one of its CO ligands under thermal conditions (333 K) to give the 32-electron complex [Mo 2Cp2(μ-COMe)(μ-PCy2)(CO)2] in high yield. The structures and bonding of both complexes, as well as that of the isostructural carboxycarbyne complex [Mo2Cp2{μ- C(CO2Me)}(μ-PCy2)-(CO)2] were studied by means of density functional theory. These calculations allow us to describe the intermetallic interaction in the edge-sharing bioctahedral dicarbonyls by a configuration of the type δ2σ2π 2-(δ*)2, with the δ* orbitais being involved in π back-bonding to the carbonyl ligands, and the δ orbitals significantly delocalized over the Mo2C(carbyne) triangle, then becoming the π-bonding component of the metal-carbyne bond. For these complexes, an atoms-in-molecules (AIM) analysis allows us to locate the corresponding intermetallic bond critical points, these exhibiting relatively high values of the electron density (ca. 0.43 e A-3). Both the MO and AIM analysis of these dicarbonyl complexes suggest that the binding of the methoxy- and carboxycarbyne ligands to the dimetal center is quite similar.
