title: EPR and DFT studies of the structure of phosphinyl radicals complexed by a pentacarbonyl transition metal.
abstract: Paramagnetic complexes M(CO)5P(C6H5)2, with M = Cr, Mo, W, have been trapped in irradiated crystals of M(CO)5P(C6H5)3 (M = Cr, Mo, W) and M(CO)5PH(C6H5)2 (M = Cr, W) and studied by EPR. The radiolytic scission of a P-C or a P-H bond, responsible for the formation of M(CO)5P(C6H5)2, is consistent with both the number of EPR sites and the crystal structures. The g and 31P hyperfine tensors measured for M(CO)5P(C6H5)2 present some of the characteristics expected for the diphenylphosphinyl radical. However, compared to Ph2P*, the 31P isotropic coupling is larger, the dipolar coupling is smaller, and for Mo and W compounds, the g-anisotropy is more pronounced. These properties are well predicted by DFT calculations. In the optimized structures of M(CO)5P(C6H5)2 (M = Cr, Mo, W), the unpaired electron is mainly confined in a phosphorus p-orbital, which conjugates with the metal d(xz) orbital. The trapped species can be described as a transition metal-coordinated phosphinyl radical.
authors.affiliation: Department of Physical Chemistry, 30 Quai Ernest Ansermet, University of Geneva, 1211 Geneva 4, Switzerland.
authors.forename: Bassirou
authors.initials: B
authors.lastname: Ndiaye
authors.forename: Shrinivasa
authors.initials: S
authors.lastname: Bhat
authors.forename: Abdelaziz
authors.initials: A
authors.lastname: Jouaiti
authors.forename: Théo
authors.initials: T
authors.lastname: Berclaz
authors.forename: Gérald
authors.initials: G
authors.lastname: Bernardinelli
authors.forename: Michel
authors.initials: M
authors.lastname: Geoffroy