The first gold(I) complexes based on thiocarbamoyl-pyrazoline ligands: Synthesis, structural characterization and photophysical properties

Abstract

Novel gold(I) complexes based on thiocarbamoyl-pyrazoline ligands were synthetized for the first time and their structural/photophysical properties were determined. Two new monocationic complexes of the type [(Ph)3PAu(L)]PF6 (L=1-thiocarbamoyl-5-(4-halophenyl)-3-phenyl-pyrazoline) were prepared by reacting (Ph)3PAuCl and ligands in the presence of KPF6 in a 1:1:1 molar ratio in a MeOH/CH2Cl2 (1:1) medium in good yields. The two cationic units from both complexes possess similar structural behaviour around the Au(I) atom which presents a two-coordinate and an almost linear coordination geometry. It was found good correlation between absorption and emission spectra and the photophysical properties were described. The prepared complexes (1 and 2) are representative examples of Au(I)/d10 compounds that present bluish luminescence in the solid state at room temperature when excited at λex=320nm. The bluish emission that appears at ca. 415nm for both cationic complexes was tentatively assigned to the LMCT excitations arising from sulphur based orbitals to the Au(I) atom (S→Au–P). Besides X-ray studies, the complete structural characterization of the prepared compounds also includes elemental analyses, IR spectroscopy, 1H and 13C NMR, UV–Vis absorption and luminescence studies.