  We investigate an effective model for organometallic complexes (with
potential uses in optoelectronic devices) via both exact diagonalisation and
the configuration interaction singles (CIS) approximation. This model captures
a number of important features of organometallic complexes, notably the
sensitivity of the radiative decay rate to small chemical changes. We find that
for large parameter ranges the CIS approximation accurately reproduces the low
energy excitations and hence the photophysical properties of the exact
solution. This suggests that electronic correlations do \emph{not} play an
important role in these complexes. This explains why time-dependent density
functional theory works surprisingly well in these complexes.
