The present paper reports a comprehensive
quantum mechanical investigation on the luminescence properties of
several mono- and dinuclear platinum(II) complexes. The electronic
structures and geometric parameters are briefly analyzed together
with the absorption bands of all complexes. In all cases agreement
with experiment is remarkable. Next, emission (phosphorescence) spectra
from the first triplet states have been investigated by comparing
different computational approaches and taking into account also vibronic
effects. Once again, agreement with experiment is good, especially
using unrestricted electronic computations coupled to vibronic contributions.
Together with the intrinsic interest of the results, the robustness
and generality of the approach open the opportunity for computationally
oriented chemists to provide accurate results for the screening of
large targets which could be of interest in molecular materials design.