FACIAL TRIS CYCLOMETALATED RH3- THEIR SYNTHESIS, STRUCTURE, AND OPTICAL SPECTROSCOPIC PROPERTIES( AND IR3+ COMPLEXES )

The synthesis of the facial tris cyclometalated complexes fac-[Rh(ppy) (3)] (ppyH = 2-phenylpyridine), fac-[Ir(ppy)(3)], and fac-[Ir(thpy)(3) ] (thpyH = 2-(2-thienyl)pyridine) by a generalized method is described . The conformation of the complexes is discussed on the basis of the H -1 NMR spectra, and for fac- [Ir(thpy)(3)] the room-temperature crysta l structure is presented: chemical formula C27H18N3S3Ir, cubic, space group Fag, Z = 8, a = 16.872(4) Angstrom A., V = 4803(3) Angstrom A(3) . The-excited-state properties are investigated by absorption, lumines cence, and luminescence line-narrowing spectroscopy in different media . The lowest excited states of fac-[(Rh(ppy)(3)] and fac-[Ir(thpy)(3)] embedded in poly(methyl methacrylate) (PMMA) correspond to ligand-cen tered 3 pi-pi transitions at 21 500 and 18 340 cm(-1), respectively, whereas for fac-[Ir(ppy),l a metal to ligand charge-transfer ((3)MLCT) lowest excited state is found. Evidence for a mixing of charge-transf er character into the (3) pi-pi() lowest excited states is provided b y the short luminescence decay times.