Photoluminescence properties of four-coordinate gold(I)-phosphine complexes of the types [Au(diphos)2]PF6 and [Au2(tetraphos)2](PF6)2

Christopher D. Delfs, Heather J. Kitto, Robert Stranger, Gerhard F. Swiegers*, S. Bruce Wild, Anthony C. Willis, Gerard J. Wilson

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    26 Citations (Scopus)

    Abstract

    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]PF6 (diphos = 1,2-bis(diphenylphosphino)ethane, 1) and [Au2(tetraphos)2](PF6)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 (λmax 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 (τ 4.1-9.4,us) 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 λmax 415-450 nm and a major emission at λmax 520-595 nm. For [Au(1)2]PF6, lifetimes of τ 251.0 ± 20.5 μs were determined for the former transition and τ 14.9 ± 4.6 μs for the latter. Density functional theory (DFT) calculations and comparative studies indicate that the former of these emissions involves triplet LMCT π*(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 π*(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.

    Original languageEnglish
    Pages (from-to)4469-4478
    Number of pages10
    JournalInorganic Chemistry
    Volume42
    Issue number14
    DOIs
    Publication statusPublished - 14 Jul 2003

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