Electronic structure of bent titanocene complexes with chelated dithiolate ligands

Gas-phase photoelectron spectroscopy and density functional theory have been utilized to investigate the interactions between the p orbitals of dithiolate ligands and d orbitals of titanium in bent titanocene complexes as minimum molecular models of active site features of pyranopterin Mo/W enzymes. The compounds Cp2Ti(S-S) [where (S-S) is 1,2-ethenedithiolate (S2C2H2), 1, 1,2-benzenedithiolate (bdt), 2, or 1,3-propanedithiolate (pdt), 3, and Cp- is cyclopentadienyl] provide access to a formal 16-electron d(0) electronic configuration at the metal. A "dithiolate-folding-effect" involving an interaction of metal and sulfur orbitals is demonstrated in complexes with arene- and enedithiolates. This effect is not observed for the alkanedithiolate in complex 3.