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.