Ultraviolet spectrum and molecular orbital studies of bis(4-R-1,2-diphenylcyclo-pentadienylzirconium(IV) dichlorides complexes (R=H, Me, Ph)

The ultraviolet spectrum was determined by experiment for the titled compounds. Their molecular orbits were calculated with the methods of DFT, and the ultraviolet spectra are calculated by TD-DFT method. The results show that the main composition of LUMO for the titled compounds is the D-orbit of zirconium, P-orbits of chlorine and π-orbit of cyclopentadienyl ring. The main composition of HOMO is the D-orbit of zirconium, P-orbits of chlorine and π-orbit of phenyl ring, without π-orbit of cyclopentadienyl ligand, because the π-orbit energy level of cyclopentadienyl ring becomes lower due to the interaction between the D-orbit of zirconium and π-orbit of cyclopentadienyl ligand. The UV spectra are the electron transition from HOMO−1, HOMO−2 and HOMO−3 to LUMO+1, LUMO+2, not from HOMO to LUMO. The molecular orbits of interaction between zirconium and cyclopentadienyl ligand are HOMO−4, HOMO−3 HOMO−2 and HOMO−1 which are lower than HOMO in energy level.