Substitution at Tricoordinate Sulfur and Phosphorus Centers

Simple derivatives of sulfoxide LXI and phosphine LXII with substituents considerably differing in electronegativity were taken as convenient models for studying stereochemistry of these reactions. 

CNDO/2 calculation results [174] are in principle very close to those described in the preceding section. As may be seen from Fig. 5.13, featuring the 

The calculated minimum energy paths of Eqs. (5.19) and (5.20) and the intermediate structures LXIc and LXIIc expected to be formed on these paths are compatible with the stereochemical outcome of the substitution reaction associated with the inversion of the pyramidal bond configuration at tricoordinate sulfur and phosphorus centers. Such a stereochemical outcome was obtained experimentally in reactions of various sulfmyl [177] and phosphinyl [178] derivatives. 

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