First isocyanoazulene and its homoleptic complexes

Abstract

An efficient synthesis of remarkably stable 6-isocyanoazulene (CN6Az), the first nonbenzenoid organic isocyanide, is described. Its superb π-accepting potential as a ligand was demonstrated through cyclic voltammetry studies on the binary complexes [Cr(CN6Az)6]0/+. The paramagnetic shift patterns for [Cr(CN6Az)6]+, the only azulenic π-system studied by paramagnetic NMR, suggest that Cr(dπ) → CN6Az(pπ*) electron delocalization involves both rings of the azulenyl substituents in [Cr(CN6Az)6]+. This conclusion is supported by density functional theory calculations on the complex [Cr(CN6Az)6][BF4]. Copyright © 2003 American Chemical Society.