RESTRICTED INVERSION OF PYRAMIDAL NITROGEN THROUGH PI-ELECTRONIC INTERACTION IN AN ACYCLIC SYSTEM

An sp(3) noninverting geometry of nitrogen in N-(isopropylylideneamino )imide stabilized by the pi-electronic system has been demonstrated th rough H-1 NMR and X-ray crystallography. One of the carbonyls and the -C=N- group of opylideneamino)-3,4-(9',10'-dihydroanthracene-9',- 10'- diyl)succinimide (4) are reduced to -CHOH and -CHNH- (8) with an exces s of sodium borohydride in methanol. Shielding parameters of isopropyl methyls and VT MMR studies of 8 have indicated a stable pyramidal geo metry of exocyclic nitrogen in solution. X-ray crystallographic studie s have demonstrated the sp(3) geometry of nitrogen (<N1N2C = 113.7 deg rees) with the lone electron pair in an anti orientation to the cage. The exo-OH configuration of 6 has suggested that the endo-hydroxy comp ound formed on reduction isomerized by thermodynamic control through t he ring-opened intermediate.