Silyl group migration in a P-silylated phosphonium ylide derived from dppm — A combined experimental and theoretical study

Abstract

Abstract The lithium complex [(Et 2 O) 2 Li{(Ph 2 P) 2 CH}] ( 2 ) was synthesized by recrystallization of the corresponding solvent-free complex in diethyl ether. The kinetic product of the reaction of 2 and Me 3 SiCl, Ph 2 PCHP(SiMe 3 )Ph 2 ( 3 ), was isolated under appropriate conditions and characterized by NMR measurement at 228 K. Both, reversible P-to-P and irreversible P-to-C migration of the silyl group were observed at higher temperatures and investigated by NMR techniques and quantum chemical calculations. The thermodynamic product Ph 2 PCH(SiMe 3 )PPh 2 ( 1 ) was found to be 84 kJ mol − 1 (B97-D/TZVPP) lower in energy than the kinetic product 3 . The molecular structures of 1 – 3 were determined by X-ray diffraction measurement.