title: Activation of white phosphorus by low-valent group 5 complexes: formation and reactivity of cyclo-P4 inverted sandwich compounds.
abstract: We report the synthesis and comprehensive study of the electronic structure of a unique series of dinuclear group 5 cyclo-tetraphosphide inverted sandwich complexes. White phosphorus (P4) reacts with niobium(III) and tantalum(III) β-diketiminate (BDI) tert-butylimido complexes to produce the bridging cyclo-P4 phosphide species {[(BDI)(N(t)Bu)M]2(μ-η(3):η(3)P4)} (1, M = Nb; 2, M = Ta) in fair yields. 1 is alternatively synthesized upon hydrogenolysis of (BDI)Nb(N(t)Bu)Me2 in the presence of P4. The trinuclear side product {[(BDI)NbN(t)Bu]3(μ-P12)} (3) is also identified. Protonation of 1 with [HOEt2][B(C6F5)4] does not occur at the phosphide ring but rather involves the BDI ligand to yield {[(BDI(#))Nb(N(t)Bu)]2(μ-η(3):η(3)P4)}[B(C6F5)4]2 (4). The monocation and dication analogues {[(BDI)(N(t)Bu)Nb]2(μ-η(3):η(3)P4)}{B(Ar(F))4}n (5, n = 1; 6, n = 2) are both synthesized by oxidation of 1 with AgBAr(F). DFT calculations were used in combination with EPR and UV-visible spectroscopies to probe the nature of the metal-phosphorus bonding.
authors.affiliation: Department of Chemistry, University of California , Berkeley, California 94720, United States.
authors.forename: Clément
authors.initials: C
authors.lastname: Camp
authors.forename: Laurent
authors.initials: L
authors.lastname: Maron
authors.forename: Robert G
authors.initials: RG
authors.lastname: Bergman
authors.forename: John
authors.initials: J
authors.lastname: Arnold
mesh_terms: D003198:Computer Simulation; D056831:Coordination Complexes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D003500:Cyclization; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010758:Phosphorus / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D010758:Phosphorus