Modification of Binuclear Pt−Tl Bonded Complexes by Attaching Bipyridine Ligands to the Thallium Site

Abstract

Complex formation of monomeric thallium(III) species with 2,2'-bipyridine (bipy) in dimethyl sulfoxide (dmso) and acetonitrile solutions was studied by means of multinuclear ((1)H, (13)C, and (205)Tl) NMR spectroscopy. For the first time, NMR signals of the individual species [Tl(bipy)(m)(solv)](3+) (m = 1-3) were observed despite intensive ligand and solvent exchange processes. The tris(bipy) complex was crystallized as [Tl(bipy)(3)(dmso)](ClO(4))(3)(dmso)(2) (1), and its crystal structure determined. In this compound, thallium is seven-coordinated; it is bonded to six nitrogen atoms of the three bipy molecules and to an oxygen atom of dmso. Metal-metal bonded binuclear complexes [(NC)(5)Pt-Tl(CN)(n)(solv)](n)(-) (n = 0-3) have been modified by attaching bipy molecules to the thallium atom. A reaction between [(NC)(5)Pt-Tl(dmso)(4)](s) and 2,2'-bipyridine in dimethyl sulfoxide solution results in the formation of a new complex, [(NC)(5)Pt-Tl(bipy)(solv)]. The presence of a direct Pt-Tl bond in the complex is convincingly confirmed by a very strong one-bond (195)Pt-(205)Tl spin-spin coupling ((1)J((195)Pt-(205)Tl) = 64.9 kHz) detected in both (195)Pt and (205)Tl NMR spectra. In solutions containing free cyanide, coordination of CN(-) to the thallium atom occurs, and the complex [(NC)(5)Pt-Tl(bipy)(CN)(solv)](-) ((1)J((195)Pt-(205)Tl) = 50.1 kHz) is formed as well. Two metal-metal bonded compounds containing bipy as a ligand were crystallized and their structures determined by X-ray diffractometry: [(NC)(5)Pt-Tl(bipy)(dmso)(3)] (2) and [(NC)(5)Pt-Tl(bipy)(2)] (3). The Pt-Tl bonding distances in the compounds, 2.6187(7) and 2.6117(5) A, respectively, are among the shortest reported separations between these two metals. The corresponding force constants in the molecules, 1.38 and 1.68 N/cm, respectively, were calculated using Raman stretching frequencies of the Pt-Tl vibrations and are characteristic for a single metal-metal bond. Electronic absorption spectra were recorded for the [(NC)(5)Pt-Tl(bipy)(m)(solv)] compounds, and the optical transition was attributed to the metal-metal bond assigned.

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

“…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).…”

Novel Luminescent Mixed‐Metal PtTl‐Alkynyl‐Based Complexes: The Role of the Alkynyl Substituent in Metallophilic and η2(π⋅⋅⋅Tl)‐Bonding Interactions

“…[52][53][54] Many of these complexes, particularly those containing Tl I , have been shown to display luminescent properties, which have invariably been attributed to intermetallic interactions; however, a number of Pt II,0 ÀTl I complexes with strong Pt-Tl interactions do not exhibit any detectable emission. [55,56] In the past two decades, much has been discovered about the photoluminescence behavior of alkynylplatinum(ii) complexes, [57][58][59][60][61][62] but, in comparison, relatively little is understood about the emissive properties of heteropolynuclear platinum systems containing alkynyl bridging ligands.…”

Thallium(I) as a Coordination Site Protection Agent: Preparation of an Isolable Zero‐Valent Nickel Tris‐Isocyanide

“…Whereas the formation of Tl I À M interactions has been well-studied, [10] considerably less attention has been paid to the behavior or persistence of these units in subsequent chemical reactions. [11] Furthermore, given the insolubility of Tl I halides in organic solvents with low dielectric constants, we reasoned that such a protecting group could be readily removed upon simple addition of external halide ions after the stepwise installation of three CNAr (5) , thereby suggesting that interactions from the CNAr Mes 2 ligand periphery are not responsible for holding the Tl atom in close proximity to the Ni center. However, it is notable that the Tl center makes a long but non-negligible contact with the triflate ion in the solid state (Tl-O1 2.696(2) ).…”