Synthesis and Luminescence of Cyclometalated Compounds with Nitrile and Isocyanide Ligands

  1. Díez, A. 1
  2. Forniés, J. 2
  3. Fuertes, S. 2
  4. Lalinde, E. 1
  5. Larraz, C. 2
  6. López, J.A. 2
  7. Martín, A. 2
  8. Moreno, M.T. 1
  9. Sicilia, V. 2
  1. 1 Universidad de La Rioja
    info

    Universidad de La Rioja

    Logroño, España

    ROR https://ror.org/0553yr311

  2. 2 Universidad de Zaragoza
    info

    Universidad de Zaragoza

    Zaragoza, España

    ROR https://ror.org/012a91z28

Revista:
Organometallics

ISSN: 0276-7333

Año de publicación: 2009

Volumen: 28

Número: 6

Páginas: 1705-1718

Tipo: Artículo

DOI: 10.1021/OM800845C SCOPUS: 2-s2.0-64649086582 WoS: WOS:000264273700017 GOOGLE SCHOLAR

Otras publicaciones en: Organometallics

Resumen

Mononuclear cationic cyclometalated palladium complexes [Pd(CΛN)(NCMe) 2]C1O 4 [CΛN = benzo-quinolinate (bzq) 1, 2-phenylpyridinate (ppy) 2], analogous to the previously described platinum complexes [Pt(CΛN)(NCMe) 2]C1O 4 [CΛN = bzq 3, ppy 4], and the isocyanide platinum benzoquinolinate [Pt(bzq)(CNR) 2]X (R = tert-butyl (t-Bu, 5), 2,6-dimethylphenyl (Xyl, 6), 2-naphthyl (2-Np, 7); X = C1O 4̄ a, PF 6̄ b) have been prepared and characterized. The solid-state structures of the cation [Pt(CΛN)(CN-Xyl) 2]+ with different counteranions (6a and 6b) were found to be different in terms of packing, although in both cases they were dominated by π-π intermoleeular interactions. The influence of the counteranion in the UV-vis spectra, both in solution and in the solid state of 5-7, is negligible. Time-dependent density-functional theory calculations on cation [Pt(CΛN)(CN-Xyl) 2]+ (6+) have been performed, suggesting that the lowest absorption is 1IL in nature mixed with some 1MLCT character. Acetonitrile platinum complexes (3, 4) are photoluminescent at low temperature (77 K) and at room temperature, whereas analogous palladium complexes (1, 2) are emissive only at 77 K (solid-state and glassy acetonitrile). Isocyanide derivatives 5-7 are intensely luminescent in all media. The emissions are assigned to ligand-centered fluorescence, to mixed 3LC/ 3MLCT phosphorescence, or to excimeric (or ground-state) 3ππ* or 3MMLCT [σ*(M)→π *(CΛN)] transitions depending on the medium and the excitation wavelength. The effect of the counteranion in governing the degree of aggregation and the extent of the interactions seem to be relatively important, especially in a rigid medium, with the smaller C1O 4̄ inducing a more excimeric character. The tendency to form π-π excimers and/or Pt...Pt oligomerization follows the order CN-2-Np > CN-t-Bu > CN-Xyl and C1O 4̄ > PF 6̄. © 2009 Amerian Chemical Society.