157402-81-8Relevant academic research and scientific papers
α-Stabilization by Silyl and Phosphino Substitution
Roemer, Bettina,Gatev, Geo G.,Zhong, Meili,Brauman, John I.
, p. 2919 - 2924 (1998)
The electron affinity of the bis(dimethylphosphino)methyl radical was measured to be 35.3+/-0.2 kcal/mol, using electron photodetachment spectroscopy in an ion cyclotron resonance spectrometer.Using equilibrium measurements, ΔHacido of bis(dimethylphosphino)methane and bis(trimethylsilyl)methane was determined to be 370+/-3 and 373+/-3 kcal/mol, respectively.From measured and known electron electron affinities and gas-phase acidities, we derive C-H bond dissociation energies: bis(dimethylphosphino)methane, 92+/-3 kcal/mol, and bis(trimethylsilyl)methane, 95+/-3 kcal/mol. ΔHacido of trimethylphosphine was bracketed at 383-387 kcal/mol.The α-stabilization effect of silyl and phosphino substitution is large and comparable in size to stabilization by thio and chloro substitution.Possible mechanisms of stabilization are discussed.
