GROUND-STATE CHARACTERISTICS AND OPTICAL-SPECTRA OF CE AND EU BIS(OCTAETHYLPORPHYRINATE) DOUBLE DECKERS

The ground state electronic structure and optical spectra of Ce(III), Ce(IV), and Eu(III) bis(octaethylporphyrin) (double deckers) are exami ned using the intermediate neglect of differential overlap (INDO/S) mo del and multireference configuration interaction (MRCI). The low-energ y electronic exited states of the bisporphyrin are interpreted in term s of their monoporphyrin contributions, and the charge transfer and ex citonic character of the transitions are analyzed. Particular attentio n is focused on the nature of the near infrared (NIR) band that charac terizes the spectra of the electron deficient bisporphyrin complex, ju stifying its shift to higher energy as the ionic radius of the central ion decreases and relating its broadness to the contribution of close ly spaced electronic transitions that become allowed through vibronic coupling. The influence of an electric perturbation on the dimeric Ce( IV) and Eu(LEI) structures is investigated and related to their conduc tivity. The results are compared to those derived from resonant Raman spectroscopy, which show the importance of the vibrational fine struct ure in the assignment of the NIR band.