title: Coordination of N2and Other Small Molecules to the Phosphorus Centre of RPW(CO)5: A Theoretical Study on the Janus Facets of the Stabilization/Activation Problem.
abstract: Bonding of neutral terminal phosphinidene tungsten(0) complexes stabilized by ligands bound to phosphorus (ligand-to-P) have been studied using a large testbed of predominantly N-ligands. Most complexes (1 a-r,v-z and 2 l) exhibit a pyramidal P centre with a formal single ligand-to-P bond order. Three ligand-to-P complexes (1 s-u) exhibit planar sp2-hybridization of P and P,N bonds featuring double bond character. All derivatives with C-ligands (1 v,x-z) exhibit a ligand-to-P bond strength intermediate between the P-N single and double bonded species. Remarkably, dinuclear complexes containing CN-(1 p,w), N3-(1 r) and N2(1-3 t) as bridging ligands between two phosphorus centres show intertwined terminal W(CO)5fragments. In particular, the case of N2bridging ligand (1-3 t) represents a noteworthy example of activation, displaying a weakened N,N bond and two sets of very strong P,N double bonds, the latter resembling the activation-picture of dinitrogen by transition metal complexes. Bond dissociation energies (BDEs) of ligand-to-P bonds do not show any correlation with a range of bond strength descriptors, but display some meaningful, roughly linear variation with the ligand softness. Based on Haaland's definition of dative bonding, a reasonable linear correlation of BDE with dativity (d1) and the dative covalence energy (DCE1) was found. A moderate correlation was also obtained with the vertical ionization potential of the ligand (I(L)) as well as with the ligands HOMO energy.
authors.affiliation: Departamento de Química Orgánica, Facultad de Química, Universidad de Murcia, Campus de Espinardo, 30100, Murcia, Spain.
authors.forename: Arturo
authors.initials: A
authors.lastname: Espinosa Ferao
authors.affiliation: Institut für Anorganische Chemie, Rheinischen Friedrich-Wilhelms-Universität Bonn, Gerhardt-Domagk-Strasse 1, 53121, Bonn, Germany.
authors.forename: Rainer
authors.identifier: http://orcid.org/0000-0003-4452-0430
authors.initials: R
authors.lastname: Streubel
keywords: bond dissociation energy; dative bonding; density functional calculations; dinitrogen activation; phosphinidenes