APPLICATION OF 2,6-DIPHENYLPYRIDINE AS A TRIDENTATE [C-BOOLEAN-AND-N-BOOLEAN-AND-C] DIANIONIC LIGAND IN ORGANOGOLD(III) CHEMISTRY - STRUCTURAL AND SPECTROSCOPIC PROPERTIES OF MONONUCLEAR AND BINUCLEAR TRANSMETALATED GOLD(III) COMPLEXES

The synthesis of a series of mono- and binuclear cyclometalated gold(I II) complexes containing the tridentate C<^>N<^>C ligand (HC<^>N<^>CH = 2,6-diphenylpyridine) was developed using K[AuCl4] and the organomer cury(II) compound Hg(C<^>N<^>CH)Cl as precursors. The molecular struct ures of [Au(C<^>N<^>C)(Spy-2)] (Spy-2 = 2-mercaptopyridine), [Au(C<^>N <^>C)PPh3]ClO4, [Au-2(C<^>N<^>C)(2)(mu-dppm)](ClO4)(2), and [Au-2(C<^> N<^>C)(2)(mu-dppe)](ClO4)(2) have been determined by X-ray crystallogr aphy. In the crystal lattice of [Au-2(C<^>N<^>C)(2)(mu-dppm)](ClO4)(2) and [Au-2(C<^>N<^>C)(2)(mu-dppe)](ClO4)(2), interplanar separations o f 3.4 Angstrom are observed between the intramolecular [Au(C<^>N<^>C)] moieties, which imply the presence of weak pi-pi interactions. The to rsion angle between the two [Au(C<^>N<^>C)] units in the former is 8.7 degrees, while a larger angle (34.2 degrees) is observed in the latte r. In the absorption spectra, the binuclear complexes show a red shift for the absorption band in the near-visible region compared to the mo nonuclear analogues. This is attributed to pi-pi interactions between the intramolecular C<^>N<^>C ligands in solution. The new complexes ar e emissive at low temperatures, (77 K) in acetonitrile.