title: Terphenyl complexes of molybdenum and tungsten with quadruple metal-metal bonds and bridging carboxylate ligands.
abstract: Mono- and bis-terphenyl complexes of molybdenum and tungsten with general composition M2(Ar')(O2CR)3 and M2(Ar')2(O2CR)2, respectively (Ar' = terphenyl ligand), that contain carboxylate groups bridging the quadruply bonded metal atoms, have been prepared and structurally characterized. The new compounds stem from the reactions of the dimetal tetracarboxylates, M2(O2CR)4 (M = Mo, R = H, Me, CF3; M = W, R = CF3) with the lithium salts of the appropriate terphenyl groups (Ar' = Ar(Xyl2), Ar(Mes2), Ar(Dipp2), and Ar(Trip2)). Substitution of one bidentate carboxylate by a monodentate terphenyl forms a M-C σ bond and creates a coordination unsaturation at the other metal atom. Hence in M2(Ar')2(O2CR)2 complexes the two metal atoms have formally a low coordination number and an also low electron count. However, the unsaturation seems to be compensated by a weak M-C(arene) bonding interaction that implicates one of the aryl substituents of the terphenyl central aryl ring, as revealed by X-ray studies performed with some of these complexes and by theoretical calculations.
authors.affiliation: Instituto de Investigaciones Químicas (IIQ), Departamento de Química Inorgánica, Universidad de Sevilla-Consejo Superior de Investigaciones Científicas , Avenida Américo Vespucio 49, 41092 Sevilla, Spain.
authors.forename: Mario
authors.initials: M
authors.lastname: Carrasco
authors.forename: Irene
authors.initials: I
authors.lastname: Mendoza
authors.forename: Michelle
authors.initials: M
authors.lastname: Faust
authors.forename: Joaquín
authors.initials: J
authors.lastname: López-Serrano
authors.forename: Riccardo
authors.initials: R
authors.lastname: Peloso
authors.forename: Amor
authors.initials: A
authors.lastname: Rodríguez
authors.forename: Eleuterio
authors.initials: E
authors.lastname: Álvarez
authors.forename: Celia
authors.initials: C
authors.lastname: Maya
authors.forename: Philip P
authors.initials: PP
authors.lastname: Power
authors.forename: Ernesto
authors.initials: E
authors.lastname: Carmona