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

Abstract

Neutralization reactions of the appropriate precursors (NBu(4))[Pt(bzq)(C[triple bond, length as m-dash]C-R)(2)] and (NBu(4))[Pt(Cinsertion markN)(CN)(2)] (Cinsertion markN = bzq, ppy) with Tl(I) salts afford [{PtTl(bzq)(C[triple bond, length as m-dash]C-R)(2)}(2)] [R = Ph (), C(5)H(4)N-2 ()] and [PtTl(Cinsertion markN)(CN)(2)] [Cinsertion markN = bzq (), ppy ()], respectively. X-Ray diffraction studies of complexes show the existence of Pt(II)-Tl(I) bonds. In .CH(2)Cl(2) the platinum-thallium units are associated in tetranuclear Pt(2)Tl(2) entities which generate a 3-D network through short Tlpi(2-py) and pipi(bzq) contacts and additional weak Cl(2)HC-Hpi(C[triple bond, length as m-dash]C) nonclassical interactions. Compounds and show extended 2-D networks by connection of the organometallic "PtTl(Cinsertion markN)(CN)(2)" units, through secondary TlN[triple bond, length as m-dash]C contacts and moderate pipi(bzq) interactions in the case of . Complexes containing the bzq group exhibit in the solid state "luminescence thermochromism" associated to dual emission. At room temperature they show an intense, visible orange (: lambda(max) 625 nm), orange-red (: lambda(max) 640 nm) or yellow (: lambda(max) 582 nm) luminescence that changes to yellowish-green (: lambda(max) 532 nm) or green [: lambda(max) 524 nm; : lambda(max) 512 nm] upon cooling to 77 K. The unstructured low energy (LE) bands attributed to (3)pi-pi* excimeric emissions due to extensive pi-pi 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-Tl bonds these HE emissions are bathochromically shifted in relation to the precursors' ones and have been tentatively assigned to a metal-metal'-to-ligand (bzq) charge transfer MM'LCT [d/s sigma*(Pt,Tl) -->pi*(Cinsertion markN)] mixed, as in the corresponding precursors, with some intraligand (3)IL[pi(Cinsertion markN') -->pi*(Cinsertion markN)] in and or ligand-to-ligand charge transfer (alkynyl to bzq) (3)LL'CT in complexes and . Complex [PtTl(ppy)(CN)(2)] , 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)-Tl(I) bond breaks down in solution.

Neutral benzoquinolate cyclometalated platinum(II) complexes as precursors in the preparation of luminescent Pt–Ag complexes

“…At low temperature, the emission profile changes and its maximum appears clearly red-shifted. The excitation spectra monitored at the low energy peaks (507, 523, 550 nm) are comparable to those observed for other benzoquinolinate complexes of Pt(II) exhibiting pÁ Á Áp stacking interactions in rigid media [21,47,83,84]. On the basis of the extended assembly observed in the crystal structure of complex 1 it seems reasonable to consider that the emission at 77 K arise from excited states corresponding to aggregates formed as a consequence of p-p interactions between bzq groups of adjacent molecules with some contribution of 3 pp ⁄ excimeric emission.…”

“…Metal-metal bonds can act as a link between different subassemblies, making them a valuable tool in molecular or crystal engineering, and giving rise to a variety of structures, from simple linear bimetallic compounds to infinite one-dimensional chains [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. Furthermore, some of these complexes show interesting photophysical and photochemical properties [1][2][3][4][5]7,8,11,17,27,[29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48], which in some cases have been exclusively attributed to the presence...…”

“…M bonds [5,[12][13][14][15][16][17]21,22,26,[28][29][30]46,[49][50][51][52][53][54][55][56][57] the acidic M center being Cu(I), Ag(I), Au(I), Cd(II), Hg(II), Tl(I), Sn(II) and Pb(II). In the course of our recent research, we have studied the use of strong ligand field cyclometalated C^N ligands, such as 7,8-benzoquinolinate (bzq), in the coordination sphere of the Pt precursor [13,14,27,47].…”

Luminescent Pt–Ag Clusters Based on Neutral Benzoquinolate Cyclometalated Platinum Complexes

“…Metallophilic interactions between closed or pseudo closed shell transition metals (d 10 , d 8 , d 10 s 2 ) is a field of great interest in Inorganic Chemistry. [1][2][3][4][5][6][7][8][9][10][11][12] In this respect, square planar complexes of Pt(II) are a particular well suited system which has allowed to prepare a huge variety of heteropolymetallic complexes involving Pt(II)(d 8 )→M dative bonds, [5,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] being the acidic M centre Cu(I), Ag(I), Au(I), Cd(II), Hg(II), Tl(I), Sn(II) and Pb(II).…”

A Luminescent Heteronuclear Cluster Featuring an Unusual Cu6 Boat‐Shaped Core Assembled by Two Dialkynyl‐Cycloplatinated Units

“…[28,29,52] Mixed dimethylpyrazolatealkynyl hexanuclear clusters Pt 2 M 4 (M = Cu, Ag, Au) were prepared through double deprotonation of the coordinated pyrazoles in [cis-Pt(CϵCPh) 2 (Hdmpz) 2 ] by the corresponding metal ions. [17] Following our interest in heteropolynuclear benzoquinolinate platinum(II)-metal complexes, [53][54][55] we report here the synthesis and the photoluminescence of a Pt 2 Cu 6 cluster [Pt 2 Cu 6 (bzq) 2 (CϵC-C 5 H 4 N-2) 6 I 2 ] (1), generated by treat- [ …”