Knowledge Bank

Laser excitation and dispersed fluorescence spectra of jet-cooled open-faced organometallic complexes, $CaC5H5$, $CaC5H4CH3$ and $CaC4H4N$ will be discussed. The electronic structure of these molecules can best be described as $Ca+$ being perturbed by $R-(R=C5H5$, $C5H4CH3$ and $C4H4N$). The electronic transitions observed here are essentially metal-centered. Their electronic spectra show extensive vibrational structure arising from excitation of skeletal and intra-ring modes. From this structure, we are able to determine the binding site of $Ca+$, i.e. above the ring in a pentahapto bonding fashion. The electronic spectra of $CaC5D5$ and $CaC4D4N$ are also presented here to provided information about ``pure” hydrogenic vibrations in $CaC5H5$ and $CaC4H4N$. In the case of $CaC5H4CH3$ methyl torsional bands are observed, from which the harrier to methyl free rotation and the change in conformation of the methyl group on $A~-X~$ excitation are determined.