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Results reveal that monodentate phosphine ligands exhibit kinetic discrimination for substrates as small as hydrogen as shown by the oxidative addition of hydrogen to the two faces of the meso isomer(R,S)-trans-Ir(P*R(sub)3)(sub)2(CO)Cl in a highly diastereoselective manner.

Experimental and computational studies on a series of cationic molybdenocene trihydride complexes, namely [Cp2MoH3]+ [(CpBut)2MoH3]+ [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(η2-H2)(H)}+ whereas the stable forms for the non-ansa complexes are classical trihydrides, (Cp2Mo(H)3]+ [(CpBut)2Mo(H)3]+, and [Cp*2Mo(H)3]+. In addition to altering the classical versus nonclassical nature of [Cp*2MoH3]+ and {(Me2Si(C5Me4)2]Mo(η2-H2)(H)}+, the [Me2Si] ansa bridge also markedly influences the stability of the complex with respect to elimination of H2 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. [ABSTRACT FROM AUTHOR]

Experimental and computational studies on a series of cationic molybdenocene trihydride complexes, namely [Cp(2)MoH(3)]+, [(Cp(Bu)t)(2)MoH(3)]+, [Cp(2)MoH(3)]+, and ([Me(2)Si(C(5)Me(4))(2)]MoH(3))+, demonstrate that the most stable form for the ansa molybdenocene derivative is a nonclassical dihydrogen-hydride isomer, ([Me(2)Si(C(5)Me(4))(2)]Mo(eta(2)-H(2))(H))+, whereas the stable forms for the non-ansa complexes are classical trihydrides, [Cp(2)Mo(H)(3)]+, [(Cp(Bu)t)(2)Mo(H)(3)]+, and [Cp(2)Mo(H)(3)]+. In addition to altering the classical versus nonclassical nature of [Cp(2)MoH(3)]+ and ([Me(2)Si(C(5)Me(4))(2)]Mo(eta(2)-H(2))(H))+, the [Me(2)Si] 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 ([H(2)Si(C(5)H(4))(2)]MoH(2)D)+ and ([H(2)Si(C(5)H(4))(2)]MoHD(2))+ establish that deuterium exhibits a greater preference than hydrogen to occupy dihydrogen versus hydride sites.