Zero-Field Splittings and Spin Densities in Ground-State Triplet Aromatic Nitrenes

This paper outlines a simple semiempirical theory of the zero-field splitting parameters of aromatic nitrenes. The theory is based on a Hückel LCAO description of the aromatic system, and takes advantage of the vanishing of odd orbital mutual atom polarizabilities in odd alternant molecules. The observed parameter for the parent imine radical is used as an empirical one-center integral. Calculated parameters agree rather well with electron spin resonance results. The relation between the zero-field parameters and general π-electron spin densities is also outlined.