PHOTOPHYSICAL AND AB-INITIO STUDIES OF MONONUCLEAR COPPER(I) COMPLEXES

Described are the photophysical properties of the mononuclear copper(I ) complexes CuL(4)(+) (L = pyridine (py), 4-methylpyridine, 4-phenylpy ridine, or acetonitrile), Cu(lut)(3)(+) (lut = 2,6-lutidine), and Cu(l ut)(2)(+). Each of these compounds as their solid PF6- salts display a relatively long-lived (>1 mu s), visible range emission at both ambie nt temperature and at 77 K but not in fluid solutions. Also reported a re the results for ab initio calculations at the restricted Hartree-Fo ck self-consistent field level to probe the natures of lower energy ex cited states of the hypothetical species CuL(n)(+) (L = NH3, CH3CN, or py; n = 1-4). These results point to an assignment of the lowest ener gy, luminactive excited states as being largely metal centered, d --> s in character for each of the above complexes with the possible excep tion of the CuL(4)(+) species where L is py or a substituted analogue. In the case of Cu(py)(4)(+) the ab initio calculations indicate a met al-to-ligand charge transfer to be the lowest energy Franck-Condon sta te, although the similarities of emission band shapes, energies, and l ifetimes among the various complexes suggest a common d --> s assignme nt.