High-Spin States and Materials

Phosphaalkenes display a number of unusual properties. An investigation of phosphaalkenes with several aryl substituents, revealed that bis(diphosphene) 19 forms a triplet dianion211. A cumulene structure was demonstrated for the Ar-P = C=C=P-Ar radical anion. The unpaired electron is predominately localized on the P atoms212. 

A new class of heteroaromatic compound was introduced by the synthesis of a diphosphathienoquinone (20). It can be reduced to a semiquinone radical anion and dianion at lower potentials than phosphaalkenes. The ESR spectrum indicates that the two P atoms are not equivalent213. 2,4 6-Tricyano- 1,3,5-triazine undergoes dimerization to yield 4,4, 6,6 -tetracyano-2,2 -bitriazine214. 

The potential energy surfaces for the fragmentation of the radical anions of p-nitrochlorobenzene and p- and m-chloroacetophenones have been explored using first principle methods215. The presence of n and a radical anions and the intramolecular ET from the ji to the o surface are reported therein. 

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