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Weir JJ, McDonough JE, Fortman G, Isrow D, Hoff CD, Scott B, Kubas GJ: 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. Inorg Chem. 2007 Feb 5;46(3):652-9.
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. |
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