Synthesis and Luminescence of Cyclometalated Compounds with Nitrile and Isocyanide Ligands

Diez, Alvaro ; Fornies, Juan (Universidad de Zaragoza) ; Fuertes, Sara ; Lalinde, Elena ; Larraz, Carmen ; Lopez, Jose A. (Universidad de Zaragoza) ; Martin, Antonio ; Moreno, M. Teresa ; Sicilia, Violeta (Universidad de Zaragoza)

Resumen: Mononuclear cationic cyclometalated palladium complexes [Pd(C∧N)(NCMe)2]ClO4 [C∧N = benzoquinolinate (bzq) 1, 2-phenylpyridinate (ppy) 2], analogous to the previously described platinum complexes [Pt(C∧N)(NCMe)2]ClO4 [C∧N = 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 = ClO4−a, PF6−b) have been prepared and characterized. The solid-state structures of the cation [Pt(C∧N)(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 intermolecular 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(C∧N)(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*(C∧N)] 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 ClO4− 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 ClO4− > PF6−.

Idioma: Inglés

DOI: 10.1021/om800845c

Año: 2009

Publicado en: Organometallics 28, 6 (2009), 1705-1718
ISSN: 0276-7333

Factor impacto JCR: 4.204 (2009)

Categ. JCR: CHEMISTRY, ORGANIC rank: 9 / 57 = 0.158 (2009) - Q1 - T1
Categ. JCR: CHEMISTRY, INORGANIC & NUCLEAR rank: 4 / 44 = 0.091 (2009) - Q1 - T1

Financiación: info:eu-repo/grantAgreement/ES/MICINN/CTQ2008-06669-C02-01-BQU
Financiación: info:eu-repo/grantAgreement/ES/MICINN/CTQ2008-06669-C02-02-BQU
Financiación: info:eu-repo/grantAgreement/ES/MEC/CTQ2005-06807-BQU

Tipo y forma: Artículo (PostPrint)

Área (Departamento): Área Química Inorgánica (Dpto. Química Inorgánica)