Reactivity in molecular crystals: radical formation in chiral phosphorus compounds

Molecular mechanics calculations, using the AMBER program (version 3.0), are presented on the radiogenic electron-capture radical formation in the crystalline chiral organophosphorus compounds (2R,4S,5R) and (2S,4S,5R) 2-chloro-3,4-dimethyl-5-phenylphospholidine 2-sulfide (respectively 1 and 2). Geometry optimization of the corresponding radical anion structures and their respective crystal surroundings reveals an increase of the Van der Waals interactions, which is significantly larger in compound 2 than in 1. This is in good agreement with previous single-crystal ESR experiments and molecular interactions calculations without geometry optimization [1].