Reactivity of phosphiranes toward nucleophiles: Theoretical and experimental investigations

The thermodynamic and kinetic parameters for the reaction of 1-methylphosphirane with dimethylphosphide (PMe2-), proceeding via attack at the ring phosphorus atom to give Me2P-PMe- plus ethylene, were calculated at the G3(MP2)-RAD(+) level. The rate constant for this mechanism (k = 1.1 x 10(13) L mol(-1) s(-1) at 25 degrees C) is seven orders of magnitude greater than that for the previously studied mechanism involving attack at carbon. Experimental investigations with 1-phenylphosphirane gave consistent results: Treatment with LiPMePh yielded no detectable polymer, and quenching with MeI gave the known diphosphine (R*,R*)-(+/-)/(R*,S*)-MePhPL PMePh. (C) 2008 Wiley Periodicals, Inc.