Theoretical interpretation of an anomalously large quadrupole splitting in poly-chlorinated ferrocene

The electronic structures of ferrocene and poly-chlorinated ferrocenes and electric field gradient at the Fe nucleus were calculated by an ab initio (coreless) MO. An anomalously large quadrupole splitting in poly-chlorinated ferrocene was accounted for the decrease of electron donation from Cp ring to esub(1g) 3d orbitals (which results in a larger absolute electric field gradient), after the elongation of Fe-Cp ring distance due to poly-Cl-substituents. (author)