LUMINESCENT D0 SCANDOCENE COMPLEXES - PHOTOPHYSICAL STUDIES AND ELECTRONIC-STRUCTURE CALCULATIONS ON CP-ASTERISK-2SCX (X = CL, I, ME)

The room-temperature luminescence and photophysics of a series of early transition metal, first-row organometallic complexes with the general formula Cp*2ScX (where Cp* is eta5-C5(CH3)5- and X represents a sigma-donating ligand) are reported. Semiempirical molecular orbital calculations using the INDO/S method (ZINDO) have been performed. The calculations were carried out using full C5(CH3)5- ligands for CP*2SCX, X = Cl, I, CH3. The calculations indicate a large amount of metal and ligand orbital mixing in these d0 complexes, with the lowest unoccupied molecular orbitals consisting principally of Sc d-orbitals admixing with the Cp* pi-orbitals. The highest-occupied molecular orbital for the chloride derivative contains primarily Cp* character, while that of the iodide species is mostly halogen in nature. The presence of a lone pair on X is requisite for room-temperature emission to occur, as evidenced by the observation of luminescence for X = Cl-, I-, and NHPh and by the lack of luminescence from CP*2ScCH3 or Cp*2ScCH2Ph, under identifical conditions.