813431-82-2Relevant academic research and scientific papers
Roles of a tetrahydroborate ligand in a facile route to ruthenium(II) ethyl hydride complexes, and a kinetic study of ethane reductive elimination
Duckett, Simon B.,Lowe, J. Claire,Lowe, John P.,Mawby, Roger J.
, p. 3788 - 3797 (2004)
The tetrahydroborate ligand in [Ru(η2-BH4)(CO) H(PMe2Ph)2], 1, allows conversion under very mild conditions to [Ru(CO)(Et)H(PMe2Ph)3], 7, by way of [Ru(η2-BH4)(CO)Et(PMe2Ph)2], 4. Deprotection of the hydride ligand in 7 (by BH3 abstraction) occurs only in the final step, thus preventing premature ethane elimination. A deviation from the route from 4 to 7 yields [Ru(η2-BH 4)(COEt)(PMe2Ph)3], 6, but does not prevent ultimate conversion to 7. Modification of the treatment of 4 yields an isomer of 7, 10. Both isomers eliminate ethane at temperatures above 250 K: the immediate product of elimination, thought to be [Ru(CO)(PMe2Ph)3], 11, can be trapped as [Ru(CO)(PMe2Ph)4], 12, [Ru(CO)H 2(PMe2Ph)3], 3a, or [Ru(CO)(C≡CCMe 3)H(PMe2Ph)3], 13. The elimination is a simple first-order process with negative ΔS? and (for 7) a normal kinetic isotope effect (kH/kD = 2.5 at 287.9 K). These results, coupled with labelling studies, rule out a rapid equilibrium with a σ-ethane intermediate prior to ethane loss.
