Tri-[Pt₂Tl]^3- and Polynuclear Chain [Pt−Tl]_∞^- Complexes Based on Nonbridged Pt^II−Tl^I Bonds: Solid State and Frozen Solution Photophysical Properties

Abstract

Treatment of (NBu4)2[PtR4] (R = C6F5) with 1 or 0.5 equiv of TlNO3 in EtOH/H(2)O produces colorless crystals of trinuclear complex (NBu4)3[Tl{PtR4}2], 1, in which the Tl+ center is complexed by two [PtR4]2- fragments (Pt-Tl = 2.9777(4) and 3.0434(4) A). The expected mixed complex with a Pt/Tl composition of 1:1, 2, is generated as an orange microcrystalline solid by treating [PtR4]2- with a large excess of TlNO3 (approximately 8 equiv). Crystallographic analysis of 2 reveals the formation of a novel one-dimensional (1D) heterometallic linear chain (NBu4)(infinity)[Tl{PtR4}](infinity), 2, formed by alternating a [PtR4]2- fragment and a Tl+ center with a uniform Pt-Tl bond separation along the chain of 3.0321(2) A. Surprisingly, treatment of (NBu4)2[PtR4] with 1 equiv of TlPF6 in EtOH yields pale greenish-yellow needles of an unusual adduct, 2.{(NBu4)(PF6)}(infinity) (3), which was found to form a similar extended linear chain, {TlPtR4}(infinity), constructed by two alternating Pt-Tl separations, a shorter (3.1028(6) A) one and a longer (3.2306(6) A) one. The solid state and solution photophysical properties have been examined. While complex 1 shows a high-energy MM'CT blue phosphorescence (450 nm), the extended chain in 2 exhibits a lower-energy emission (582 nm) than that in adduct 3 (505 nm). For products 2 and 3, interesting luminescence thermochromism is observed in frozen solutions. The emissions are found to be strongly dependent on the solvent, concentration, and excitation wavelength.

Halide Addition/Abstraction in Phosphido Derivatives: Isolation of the Thallium and Silver Intermediates

“…Similar spectroscopic features have been observed in other complexes displaying Tl · · · F interactions. 19,22,23,27 Analogously, the 19 F NMR spectrum of 8 at room temperature shows very broad, overlapped signals with platinum satellites for the o-F atoms, which split into six signals (1:1:3:1:1:1 intensity ratio) at 183 K. The more-intense signal is broad, and some of the platinum satellites appear overlapped. In the higher field region (m-and p-F atoms) the signals due to 12 inequivalent fluorine atoms appear overlapped.…”

“…All of these geometric parameters are in agreement with a Pt-Tl bond. [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] A noteworthy feature of this structure is the presence of o-F · · · Tl contacts, with distances Tl-F (15) ) 2.951(7) Å and Tl-F(20) ) 3.014(7) Å, which are in the range found in platinum(II) complexes containing Pt-Tl bonds, 19,22,23,27 or thallium complexes containing intra- [37][38][39][40] or intermolecular F · · · Tl contacts. 26,29,37,[41][42][43][44][45] These o-F · · · Tl contacts are also detected in solution in the 19 F NMR spectra of 5 (below).…”

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

“…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].…”

Silver(i) and thallium(i) cations as unsupported bridges between two metal bases

“…Likewise, the heavy cation Tl + has been shown to act as an unsupported bridge between divalent Group 10 fragments but never zerovalent derivatives. 30,31,41 Similarly confounding is that neither of these cations have been shown to act as unsupported bridges in metal-only Lewis pairs (MOLPs) with Group 8 fragments. 42 Early results in our laboratory aimed at one-pot oxidative addition / halide abstraction of alkyl halides to [Pt(PPh 3 ) 4 ] gave small amounts of a side product that appeared to contain an Ag + cation spanning two Pt 0 centres, but unfortunately could not be obtained as a pure compound.…”