Stereomutation at an octahedral transition-metal center: Energetics of hydride transit between syn and anti faces of the bis(diphenylphosphinopropyl)(methyl)silyl (biPSi) complex RuH(biPSi)(CO)2

Article abstract of DOI:10.1021/om0100939

Reaction of SiH(Me)(CH₂CH₂CH₂PPh₂)₂, bi-PSiH , with Ru(PPh₃)₂(CO)₃ affords quantitatively the phosphinoalkylsilyl complex RuH(biPSi)(CO)₂, as a mixture of the crystallographically characterized syn diastereomer 3-s and its anti correspondent 3-a; subsequent treatment with CCl₄ then LiAl²H₄ provides access to the deuterioisotopomer Ru²H(biPSi)(CO)₂, 3-d₁. Slow stereomutation of pure 3-s to an equilibrium mixture 3-s/3-a (4.5:1, 295 K) occurs with ΔG?₂₉₅, 102(5) kJ mol^-1; ΔH?₂₉₅, 113(7) kJ mol^-1; ΔS?₂₉₅, 37(2) J K^-1 mol^-1; this is not accompanied by incorporation of external ¹³CO, shows only a minor isotope effect vs 3-d₁, and is concluded to be nondissociative.