Electronic transitions of racemic ethylene-bridged bis(indenyl)-type siloxy substituted zirconocene dichlorides. A combined UV/VIS spectroscopic and theoretical study

The ligand to metal charge transfer (LMCT) transitions of racemic siloxy substituted ethylene bridged bis(indenyl)-type zirconocenes were studied using UV/VIS spectroscopy in combination with ab initio Hartree–Fock and hybrid density functional B3LYP methods. Clear correlations between the experimental LMCT absorption energies and theoretical HOMO–LUMO energy gaps were observed. The LMCT absorption energies were analysed as a function of the ligand structure. Hydrogenation of the indenyl ring and position of the siloxy substituent have strong influences on HOMO–LUMO energy gaps, and consequently on the observed absorption energies. p