Extended structures containing Pt(ii)–Tl(i) bonds. Effect of these interactions on the luminescence of cyclometalated Pt(ii) compounds

Forniés, Juan (Universidad de Zaragoza) ; Fuertes, Sara ; Martín, Antonio ; Sicilia, Violeta (Universidad de Zaragoza) ; Gil, Belén ; Lalinde, Elena

Resumen: Neutralization reactions of the appropriate precursors (NBu4)[Pt(bzq)(C‚â°.tbd;C‚ÄìR)2] and (NBu4)[Pt(C‚ÅÅN)(CN)2] (C‚ÅÅN = bzq, ppy) with Tl^I salts afford [(PtTl(bzq)(C‚â°.tbd;C‚ÄìR)2)2] [R = Ph (1), C5H4N-2 (2)] and [PtTl(C‚ÅÅN)(CN)2] [C‚ÅÅN = bzq (3), ppy (4)], respectively. X-Ray diffraction studies of complexes 2‚Äì4 show the existence of Pt^II-Tl^I bonds. In 2¬¿CH2Cl2 the platinum‚Äìthallium units are associated in tetranuclear Pt2Tl2 entities which generate a 3-D network through short Tl‚ãØŒ†(2-py) and Œ†‚ãØŒ†(bzq) contacts and additional weak Cl2HC‚ÄìH‚ãØŒ†(C‚â°.tbd;C) nonclassical interactions. Compounds 3 and 4 show extended 2-D networks by connection of the organometallic ‚ÄúPtTl(C‚ÅÅN)(CN)2‚Äù units, through secondary Tl‚ãØN‚â°.tbd;C contacts and moderate Œ†‚ãØŒ†(bzq) interactions in the case of 3. Complexes 1‚Äì3 containing the bzq group exhibit in the solid state ‚Äúluminescence thermochromism‚Äù associated to dual emission. At room temperature they show an intense, visible orange (1: Œõmax 625 nm), orange-red (2: Œõmax 640 nm) or yellow (3: Œõmax 582 nm) luminescence that changes to yellowish-green (1: Œõmax 532 nm) or green [2: Œõmax 524 nm; 3:max 512 nm] upon cooling to 77 K. The unstructured low energy (LE) bands attributed to ³Œ†‚Ä쌆*excimeric emissions due to extensive Œ†‚Ä쌆 interactions are dominant at room temperature. By contrast, the high energy (HE) bands are highly structured and predominant at 77 K. Due to the presence of Pt‚ÄìTl bonds these HE emissions are bathochromically shifted in relation to the precursors‚Ä= ones and have been tentatively assigned to a metal-metal‚Ä=-to-ligand (bzq) charge transfer MM‚Ä=LCT [d/s œÉ*(Pt, Tl) ‚Ü팆*(C‚ÅÅN)] mixed, as in the corresponding precursors, with some intraligand ³IL[Œ†(C‚ÅÅN‚Ä=) ‚Ü팆*(C‚ÅÅN)] in 3 and 4 or ligand-to-ligand charge transfer (alkynyl to bzq) ³LL‚Ä=CT in complexes 1 and 2. Complex [PtTl(ppy)(CN)2] 4, which does not show short contacts between the phenylpyridinate groups in solid state, only shows the HE green structured band both at 298 K and at 77 K. Only the cyanide derivatives are soluble and both spectroscopic (NMR and UV-Vis) and emission data (MeOH, 298 K and 77 K) indicate that the Pt^II‚ÄìTl^I bond breaks down in solution. ¬© 2009 The Royal Society of Chemistry.

Idioma: Inglés

DOI: 10.1039/b819323a

Año: 2009

Publicado en: Dalton Transactions 62, 12 (2009), 2224
ISSN: 1477-9226

Factor impacto JCR: 4.081 (2009)

Categ. JCR: CHEMISTRY, INORGANIC & NUCLEAR rank: 7 / 44 = 0.159 (2009) - Q1 - T1

Tipo y forma: Artículo (Versión definitiva)

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