Peculiarities of pπpπ conjugation in aminosubstituted phosphaalkenes

Effets of pπpπ conjugation in phosphaalkenes have been considered by taking into account the results of X‐ray structural studies and ab initio quantum‐chemical calculations. The structural consequences of the conjugation depend to a certain extent on the character of the substituent and the place of its attachment to the double PC bond. Depending on the location of the substituent, bond polarization may strengthen or weaken (compensate for) the conjugation effects. A high contribution of the s‐character of the lone electron pair of the P atom is an essential feature of the electron structure of a phosphaalkene.