Electron spin resonance spectrum of bis(4-phenylamino-2-phenyliminopent-3-enato-NN′)copper(II); a complex having both a low Azzand low-energy d-d band

Abstract
Bis(4-phenylamino-2-phenyliminopent-3-enato-NN′)copper(II)(I), having a low energy dd band characteristic of near-tetrahedral stereochemistry, shows an e.s.r. spectrum (as a doped sample of the zinc analogue) with a low A(Cu)(107 × 10–4 cm–1); the relevance of this spectrum to the stereochemistries proposed for ‘blue’ copper proteins is discussed.