| 12844321 |
Delfs CD, Kitto HJ, Stranger R, Swiegers GF, Wild SB, Willis AC, Wilson GJ: Photoluminescence properties of four-coordinate gold (I)-phosphine complexes of the types [Au (diphos) 2] PF6 and [Au2 (tetraphos) 2](PF6) 2. Inorg Chem. 2003 Jul 14;42(14):4469-78.
Numerous reports describe the photoluminescence of two- and three-coordinate gold (I)-phosphine complexes, but emission in their analogous four-coordinate complexes is almost unknown. This work examines the luminescence of tetrahedral gold (I) complexes of the types [Au (diphos)(2)] PF (6) (diphos = 1,2-bis (diphenylphosphino) ethane, 1) and [Au (2)(tetraphos)(2)](PF (6))(2) (tetraphos = (R,R)-(+/-)/(R,S)-1,1,4,7,10,10-hexaphenyl-1,4,7,10-tetraphosphadecane, (R,R)-(+/-)/(R,S)-2). Although nonemitting in solution, these complexes luminesce with an intense yellow color (lambda (max) 580-620 nm) at 293 K in the solid state or when immobilized as molecular dispersions within solid matrixes. The excited-state lifetimes of the emissions (tau 4.1-9.4 micros) are markedly dependent on the inter- and intramolecular phenyl-phenyl pairing interactions present. At 77 K in an ethanol glass, two transitions are observed: a minor emission at lambda (max) 415-450 nm and a major emission at lambda (max) 520-595 nm. For [Au (1)(2)] PF (6), lifetimes of tau 251.0 +/- 20.5 micros were determined for the former transition and tau 14.9 +/- 4.6 micros for the latter. Density functional theory (DFT) calculations and comparative studies indicate that the former of these emissions involves triplet LMCT pi (Ph) --> Au (d)-P (p) transitions associated with individual P-phenyl groups. The latter emissions, which are the only ones observed at 293 K, are assigned to LMCT pi (Ph-Ph) --> Au (d)-P (p) transitions associated with excited P-phenyl dimers. Other tetrahedral gold (I)-phosphine complexes containing paired P-Ph substituents display similar emissions. The corresponding phosphine ligands, whether free, protonated, or bound to Ag (I), do not exhibit comparable emissions. Far from being rare, luminescence in four-coordinate Au (I)-phosphine complexes appears to be general when stacked P-phenyl groups are present. |
81(1,1,1,1) |