title: Synthesis, structure, and thermochemistry of the formation of the metal-metal bonded dimers [Mo(mu-TeAr)(CO)3(PiP3)]2 (Ar = phenyl, naphthyl) by phosphine elimination from *Mo(TePh)(CO)3(PiPr3)2.
abstract: The complexes (*TeAr)Mo(CO)3(PiPr3)2 (Ar = phenyl, naphthyl; iPr = isopropyl) slowly eliminate PiPr3 at room temperature in a toluene solution to quantitatively form the dinuclear complexes [Mo(mu-TeAr)(CO)3(PiPr3)]2. The crystal structure of [Mo(mu-Te-naphthyl)(CO)3(PiPr3)]2 is reported and has a Mo-Mo distance of 3.2130 A. The enthalpy of dimerization has been measured and is used to estimate a Mo-Mo bond strength on the order of 30 kcal mol-1. Kinetic studies show the rate of formation of the dimeric chalcogen bridged complex is best fit by a rate law first order in (*TeAr)Mo(CO)3(PiPr3)2 and inhibited by added PiPr3. The reaction is proposed to occur by initial dissociation of a phosphine ligand and not by radical recombination of 2 mol of (*TeAr)Mo(CO)3(PiPr3)2. Reaction of (*TePh)Mo(CO)3(PiPr3)2, with L = pyridine (py) or CO, is rapid and quantitative at room temperature to form PhTeTePh and Mo(L)(CO)3(PiPr3)2, in keeping with thermochemical predictions. The rate of reaction of (*TeAr)W(CO)3(PiPr3)2 and CO is first-order in the metal complex and is proposed to proceed by the associative formation of the 19 e- radical complex (*TePh)W(CO)4(PiPr3)2 which extrudes a *TePh radical.
authors.affiliation: Department of Chemistry, University of Miami, Coral Gables, Florida 33124, USA.
authors.forename: John J
authors.initials: JJ
authors.lastname: Weir
authors.forename: James E
authors.initials: JE
authors.lastname: McDonough
authors.forename: George
authors.initials: G
authors.lastname: Fortman
authors.forename: Derek
authors.initials: D
authors.lastname: Isrow
authors.forename: Carl D
authors.initials: CD
authors.lastname: Hoff
authors.forename: Brian
authors.initials: B
authors.lastname: Scott
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Kubas