Luminescent d0 Scandocene Complexes: Photophysical Studies and Electronic Structure Calculations on Cp*2ScX (X = Cl, I, Me)

Abstract

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 η5-C5(CH3)5− and X represents a σ-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* π-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. © 1993, American Chemical Society. All rights reserved.