Molybdenocene Trihydride Complexes: Influence of a [Me<sub>2</sub>Si] <i>Ansa</i> Bridge on Classical versus Nonclassical Nature, Stability with Respect to Elimination of Dihydrogen, and Acidity
作者:Kevin E. Janak、Jun Ho Shin、Gerard Parkin
DOI:10.1021/ja047554c
日期:2004.10.1
Experimental and computational studies on a series of cationic molybdenocene trihydride complexes, namely [Cp2MoH3](+), [(Cp-But)(2)MoH3](+), [Cp*2MoH3](+), and [Me2Si(C5Me4)(2)]MoH3}(+), demonstrate that the most stable form for the ansa molybdenocene derivative is a nonclassical dihydrogen-hydride isomer, [Me2Si(C5Me4)(2)]Mo(eta(2)-H-2)(H)}(+), whereas the stable forms for the non-ansa complexes are classical trihydrides, [Cp2Mo(H)(3)](+), [(CPBut)(2)Mo(H)(3)](+), and [Cp*Mo-2(H)(3)](+). In addition to altering the classical versus nonclassical nature of [Cp*2MoH3](+) and [Me2Si(C5Me4)(2)]Mo(eta(2)-H-2)(H)}(+), the [Me2Si] ansa bridge also markedly influences the stability of the complex with respect to elimination of H-2 and dissociation of H+. Finally, computational studies on [H2Si(C5H4)(2)]MoH2D}(+) and [H2Si(C5H4)(2)]MoHD2}(+) establish that deuterium exhibits a greater preference than hydrogen to occupy dihydrogen versus hydride sites.