Thallium Atoms Research Articles

A neutron diffraction and 205Tl NMR study of the thallium germanate glass system

Neutron diffraction data, measured for two thallium germanate glass compositions, are presented and compared with previously published data for caesium germanate glasses. The measured coordination number, n Ge–O, for the 10 mol% Tl 2O thallium germanate glass is in good agreement with the average coordination number measured for the equivalent caesium germanate. However, while n Ge–O declines for caesium germanate glasses as the amount of modifier increases above 18 mol% Cs 2O, n Ge–O for the 30 mol% Tl 2O thallium germanate glass remains high with, on average, 4.40 ± 0.03 oxygen neighbours per germanium. The difference in behaviour of the germanium coordination, compared to caesium germanate glasses, arises from a change in the average thallium environment, as the role of the thallium changes from that of a modifier (similar to an alkali), to a role where some of the thallium atoms act as network formers. This is supported by 205Tl NMR measurements which indicate the presence of two thallium environments.

Isotope Selective Optical Pumping in a Dense Thallium Atomic Beam

Isotope selective optical pumping has been investigated in a dense thallium atomic beam. The ground state thallium atoms are optically pumped to metastable atoms by using a frequency-doubled single-mode continuous Ti:Sapphire laser. The relative population of the metastable atoms of Tl and Tl has been obtained by measuring the absorption strength of the metastable atoms after optical pumping. The isotope selectivity of the optical pumping technique strongly depends on the power broadening effect. In addition, collisional energy transfer, such as inter-atomic collisions, and the hyperfine state changing collision is discussed.

Fluoride ion donor properties of group 13 trifluorides (MF3, M = Al, Ga, In, Tl) and crystal structures of InF3·3SbF5, TlF3·3SbF5 and TlF3·AsF5·2HF

Reactions between strong Lewis acids (i.e. AsF5, SbF5) and MF3 (M = Al, Ga, In, Tl) in anhydrous hydrogen fluoride at ambient temperature proceeded only in three cases, yielding InF3·3SbF5, TlF3·3SbF5, TlF3·AsF5·2HF and TlF3·AsF5. Crystal structure of InF3·3SbF5 consists from infinite chains of In atoms connected by three SbF6 units, with two bridging fluorine atoms (Fb) in cis-position. Due to the strong interaction of SbF6 units with In3+, the Sb–Fb bonds are significantly elongated (200.7(4) pm). Such long Sb–Fb bonds have been observed in the crystal structure of SbF5. The crystal structure of TlF3·3SbF5 is built from slabs where thallium atoms are connected by SbF6 units. The thallium is nine-fold coordinated by fluorine atoms in the shape of a tricapped trigonal prism. In the crystal structure of TlF3·AsF5·2HF there are puckered layers, composed of rectangular rings made of Tl and F atoms. The seven-fold coordination around each Tl is completed by three axial fluorine atoms, provided by one HF molecule and two AsF6 units arranged below and above the puckered layers forming infinite slabs on that way. The second molecule of HF is placed between the slabs. Vibrational spectra of isolated InF3·3SbF5, TlF3·3SbF5, and TlF3·AsF5 are consistent with the presence of highly deformed SbF6/AsF6 octahedra.

Element Lines: Bonding in the Ternary Gold Polyphosphides, Au2MP2 with M = Pb, Tl, or Hg

We present a theoretical study of the electronic structures of Au(2)PbP(2), Au(2)TlP(2), and Au(2)HgP(2). Structurally, these compounds contain a framework of condensed Au(2)P(6) and Au(4)P(6) rings forming parallel channels, which are filled by lead, thallium, or mercury atoms. Given the linear coordination of the Au atoms and the existence of zigzag -[P-P-P]- singly-bonded chains in them, these materials present us with a rare instance of approximately linear, one-dimensional, and zerovalent element (Pb, Tl, or Hg) chains with a variable electron count. The Pb-Pb, Tl-Tl, and Hg-Hg element lines in these structures have somewhat longer bond lengths than their respective single bond lengths or their separations in (calculated) isolated chains. Yet, the zerovalent element interactions are prominent and are responsible for the metallicity of some of these materials. In the calculations, both Au(2)PbP(2) and Au(2)TlP(2) emerge as metallic, whereas Au(2)HgP(2) is a semiconductor. The isolated element chains do not undergo a pairing (Peierls) distortion nor do the chains in the three-dimensional ternaries. The small barrier for mobility of the Pb, Tl, and Hg atoms along the chain axis may explain the large thermal parameters observed in the crystal structures along the chain axis (and the need to use fractional occupations of several positions along the chain). These ternaries may show one-dimensional liquidlike behavior under some conditions.

Thallium(III) chloride in organic solvents: Synthesis, solutions and solvates. The crystal structures of trichlorobis(dimethylsulfoxide)thallium(III) and tribromobis(dimethylsulfoxide)thallium(III)

The synthesis of thallium(III) chloride and bromide was performed in solution by chlorination and bromination, respectively, of the suspensions of the corresponding thallium(I) halides in acetonitrile. Crystalline compounds TlX 3(CH 3CN) 2 (X = Cl −, Br −) were prepared from the acetonitrile solutions. Thallium(III) chloride and bromide in dimethylsulfoxide solution were obtained by dissolving the corresponding solid compounds TlX 3(CH 3CN) 2 (Cl −, Br −) in DMSO. Both acetonitrile and dimethylsulfoxide solutions of thallium(III) chloride were studied by UV–Vis and 205Tl NMR spectroscopy. The UV–Vis study of the TlCl 3–CH 3CN system showed presence of at least two thallium(III) chloride species. Only one signal arising from the thallium(III) species was, however, detected by the 205Tl NMR in the solution because of the fast chemical exchange. The 205Tl NMR study of thallium(III) chloride in dimethylsulfoxide showed three separate signals assigned to the solvated TlCl 4 - , TlCl 3 and TlCl 2 + species. The crystalline compounds of trichlorobis(dimethylsulfoxide)thallium(III) and tribromobis(dimethylsulfoxide)thallium(III) were prepared and their crystal structures were solved by single-crystal X-ray analysis. The thallium atom in the complexes has a trigonal bipyramidal environment built by three halide ions occupying equatorial positions of the polyhedron and two oxygen atoms of the DMSO molecules in the apical positions.

Theoretical and experimental study of some basic processes in He-TlI and Ne-TlI plasma - asymmetric charge transfer, penning ionization and diffusion

The diffusion coefficients of thallium and iodine atoms in a binary system with helium and neon are calculated on the basis of 12-6 Lenard-Jones and rigid sphere models. Cross-sections and rate constants for thermal energy charge transfer into some Tl+ and I+ excited states are theoretically and experimentally obtained for a gas discharge in He-TlI and Ne-TlI mixtures. Cross-sections and rate constants for Penning ionization into Tl+ and I+ ground and excited states are calculated for Penning collisions with the He and Ne metastable atoms. Since the characteristic constants studied depend on the gas temperature, the radial gas temperature distribution is also calculated through solving the heat conduction equation.

Laser spectroscopy of the thallium atom based on transitions 6p 1/2 → 6D 3/2 → nF 5/2 (n = 13–24)

The energies and quantum defects of Rydberg states nF 5/2 (n = 13–24) of the thallium atom have been studied experimentally. The Rydberg states were excited from the ground state 62 P 1/2 by the two-stage scheme through the intermediate state 62 D 3/2. By using a collimated atomic beam and monochromatic radiation of two narrow-band tunable lasers, we have succeeded in resolving the hyperfine and isotopic structures of the ground state of the thallium atom and in determining the energy positions of the states nF 5/2 accurate to 0.03 cm−1, which exceeds the accuracy achieved in the previous works by more than an order of magnitude. The quantum defect of nF 5/2 states is independent of n within the measurement accuracy and is equal to Δ = 1.0344 ± 0.0008. The ionization potential I p = 49266.55 ± 0.03 cm−1 has been found for the 205Tl isotope from the level 62 P 1/2 (F = 0). The energy of the 62 D 3/2 level measured experimentally relative to the state F = 0 of the 205 isotope amounted to 36118.56 ± 0.02 cm−1.

Luminescent One- And Two-Dimensional Extended Structures and a Loosely Associated Dimer Based on Platinum(II)–Thallium(I) Backbones

Neutralization reactions between (NBu4)2[ trans-Pt(C 6F5)2(CN)2] 1 and (NBu4)2[cis-Pt(C6F5)2(CN)2] 2 with TlPF 6 have been carried out, and the resulting structures of [trans,trans,trans-Tl2{Pt(C6F5)2(CN)2}.(CH3COCH3) ] n [4.(CH3COCH3)2] n and {Tl[Tl{cis-Pt(C6F5)2(CN)2}].(H2O)} n [5.(H2O)] n have been determined by X-ray crystallography. Remarkably, the change from trans to cis geometry on the platinum substrate causes a significant decrease in the Pt(II)...Tl(I) metallophilic interaction. Thus, the platinum center in the trans fragment easily connects with two Tl(I) ions forming a distorted pseudo-octahedron PtTl2, which generates a final two-dimensional layered structure by secondary additional intermolecular Tl(I)...N(CN) interactions. However, the [cis-Pt(C6F5)2(CN)2] (2-) fragment interacts strongly with just one Tl center leading to an extended helical [-Pt-Tl-Pt-Tl-] n(n-) chain. In this case, the second thallium center neutralizes the anionic chain mainly through Tl...N(CN) ( intra) and Tl...F(C 6F 5) (intra and inter)actions. The reaction of TlPF 6 with the monoanionic fragment (NBu4)[cis-Pt(C6F5)2(CN)(PPh2C[triple bond]CPh)] 3 yields the discrete associated dimer [Tl{cis-Pt(C6F5)2(CN)(PPh2C[triple bond]CPh)}] 2 [ 6] 2. Dimer [ 6] 2 could be described as two square pyramids with the thallium atoms in the apical positions, connected through Tl...N(cyano) interactions. The final heteropolynuclear Pt-Tl complexes, except 4 at room temperature, show bright emission in the solid state when irradiated with UV-vis radiation, in contrast to the precursors 1 and 3, which are not luminescent. This difference indicates that the emissions in 4- 6 are presumably related to the interaction between the metal centers. The Pt-Tl bonding interactions and, consequently, the emissive properties are lost in solution at room temperature, as shown by the conductivity and NMR measurements. However, variable-concentration luminescence measurements in glassy acetonitrile solutions indicate the formation of different aggregates with different degrees of Pt...Tl interactions for 4 and 5 and a dimeric structure similar to that observed in solid state for 6.

External-cavity frequency doubling of a 5-W 756-nm injection-locked Ti:sapphire laser

We have developed a 5-W 756-nm injection-locked Ti:sapphire laser and frequency-doubled it in an external enhancement cavity for the generation of watt-level 378-nm single-frequency radiation, which is essential for isotope-selective optical pumping of thallium atoms. With a lithium triborate (LBO) crystal in the enhancement cavity, 1.1 W at 378 nm was coupled out from the cavity. Such results are to our knowledge the highest powers of continuous-wave single-frequency radiation generated from a Ti:sapphire laser and its frequency doubling.

Ab initiostudy of thallium nanoclusters onSi(111)−7×7

We have studied the stability of a thallium nanocluster of various numbers of atoms $(N=1,2,\dots{},10)$ on a $\mathrm{Si}(111)\text{\ensuremath{-}}7\ifmmode\times\else\texttimes\fi{}7$ substrate using density functional theory total energy calculations. We have compared it with clusters of other group III elements (Al, Ga, and In). Thallium is found to be unstable with the triangular cluster, which has been known to be stable for other group III elements. Instead, a slightly different structure, in which Si atop atoms are lower than thallium atoms in height by $2.56\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$, was found to be quite stable. Such an abnormal structure originates from the inert pair of $6{s}^{2}$ electrons due to the significant spin-orbit interaction. The initial relaxed $N=6$ Tl cluster continues to grow with increasing $N$ up to $N=9$ in the faulted-half unit cell, which is consistent with experimental observations.

Theoretical study of the aggregation of d 10–s 2 Au(I)–Tl(I) complexes in extended unsupported chains

Model compounds are used to study the metallophilic attraction between gold and thallium atoms. Ab initio calculations on dimers and tetramers in different distributions of the minimal units are analyzed. An attraction is found for all models and there is a reasonable agreement between the experimental and theoretical geometries at the HF and MP2 levels.

Highly polyhapto–aromatic interactions in thallium(I) coordination

In the solid state, the Tl(I) complex of 4-hydroxybenzoate (HB −), [Tl(HB)] n ( 1), can be regarded as containing polymeric chains linked through 2 × η 6 interactions of the Tl atoms with phenyl groups from adjacent units. The thallium atoms contain close Tl I ⋯ π (aromatic) contacts, thus attaining a total hapticity of 16 with environments TlO 4C 12. The unusually high coordination number in the this compound may reflect the capacity of Tl(I) to act as both a Lewis acid and a Lewis base.

Thermal and structural studies of two new TlI three-dimensional coordination polymers, [Tl2(μ-CSB)] n and [Tl2(μ-ADC)] n , CSB2− =4-[(4-carboxyphenyl)sulfonyl]-1-benzenecarboxylate and ADC2− =acetylendicarboxylate

Two new 3D coordination polymers, [Tl2(μ10-CSB)] n (1) [CSB = 4-[(4-carboxyphenyl)sulfonyl]-1-benzenecarboxylate] and [Tl2(μ9-ADC)] n (2) [ADC = acetylendicarboxylate], have been synthesized and characterized by elemental analysis, and IR spectroscopy. Thermal behavior and structures of 1 and 2 have been studied. Single-crystal X-ray data of 1 show that the thallium atoms have an irregular coordination sphere containing a stereochemically active lone pair with TlO5 environment. The single-crystal X-ray data of 2 showed that there are two different Tl environments. One Tl is six-coordinate with a weak Tl ··· Tl interaction with a distance of 3.904 Å. The other type of Tl in the TlO5C2Tl units is eight-coordinate with one weak Tl ··· Tl and two short Tl ··· C interactions.

Thermal, fluorescence, structural and solution studies of a thallium(I) one-dimensional coordination polymer with 4-aminobenzoate (AB −), [Tl(μ 4-AB)] n

A thallium(I) one-dimensional polymer, [Tl(μ 4-AB)] n ( 1) [HAB = 4-aminobenzoic acid], has been synthesized and characterized. The single-crystal X-ray data of compound show the coordination number in the Tl I ions is five, the thallium atoms have irregular coordination sphere containing stereo-chemically active lone pair and bi-hapto (η 2) interactions, thus attaining a total hapticity of seven with environment C 2O 5Tl. The thermal stability of 1 was studied by thermal gravimetric (TG) and differential thermal analyses (DTA). The ligand HAB and compound 1 are luminescent in the solution state, with emission maxima at 395 nm. The results of studies of the stoichiometry and formation of complex of 1 in DMF solution were found to be in support of their solid state stoichiometry.

Isotope Selective Optical Pumping of Thallium Atoms in a Vapor Cell

Also, we performed the experiment with the same parameters in a heat oven. The numerical results, such as the widths and the shifts of the absorption signals of the thallium metastable atoms in the optical pumping, are compared with the experimental results. We also discussed the collision eect in the heat oven.

A novel tetranuclear cubic cage, [Tl 4(μ 3-dcp) 4] {Hdcp=2,4-dichlorophenol}, new short Cl⋯Cl interactions, thermal, fluorescence, structural and solution studies

The single crystal X-ray analysis of a novel Tl I complex of 2,4-dichlorophenol (Hdcp) ligand shows that the complex has a tetranuclear cubic cage as a result of bridging ligands dcp − with basic repeating of [Tl(μ 3-dcp)] units. There are four thallium atoms with similar coordination spheres in the cubic cage. These thallium atoms contain irregular coordination sphere with stereo-chemically active lone pair. The thermal stability of [Tl 4(μ 3-dcp) 4] was studied by thermal gravimetric (TG) and differential thermal analyses (DTA). The compound [Tl 4(μ 3-dcp) 4] is luminescent in the solution state with emission maxima at 397 nm. The results of studies of the stoichiometry and formation of [Tl 4(μ 3-dcp) 4] complex in DMF solution were found to be in support of their solid state stoichiometry.

Influence of the polarization of radiation on the shape of resonances of coherent population trapping on fine-structure levels

The dependence of the shape of resonances of coherent population trapping (CPT) on magnetic sublevels of thallium atoms, forming a generalized Λ-system with the magnetic sublevels of the fine-structure levels as lower ones, on the polarization of the radiation fields has been numerically studied. The cases of linear, elliptical, and circular polarizations have been considered. The shape and the number of CPT resonances for different polarizations have been compared. It has been concluded that the electromagnetically induced transparency can be changed by changing the polarization properties of the laser radiation. The possibility to decrease the number of observed resonances may be useful in high-resolution spectroscopy.

Two new examples of very short thallium–transition metal contacts: Tl 3Ag 3Sb 2S 6 and Tl 3Ag 3As 2S 6

Two new sulphosalts Tl 3Ag 3Sb 2S 6, ( 1) and Tl 3Ag 3As 2S 6, ( 2) were prepared in reaction of synthetic binary sulfides: argentite (Ag 2S), carlinite (Tl 2S) and orpiment (As 2S 3) or stibnite (Sb 2S 3), and their crystal structures have been determined using single-crystal data. The compounds are isostructural and crystallize in the space group P2 1/ c ( Z = 4), with a = 11.6854(17) Å, b = 11.8602(17) Å, c = 12.1294(18) Å, β = 123.356(2)°, V = 1404.1(4) Å 3 for 1, and a = 11.4415(14) Å, b = 11.7530(15) Å, c = 11.9880(16) Å, β = 123.516(3)°, V = 1344.0(3) Å 3 for 2. Refinements involving anisotropic displacement parameters for all atoms converged to the conventional R-factors: R 1 = 0.0496 for 1 and R 1 = 0.0372 for 2. The structures consist of two kinds of slabs alternately situated along [1 0 0] direction and sharing S atoms located between them. The first slab is built up of Tl1S 8, Tl2S 6, Tl3S 5Ag3 coordination polyhedra and Ag3S 3Tl3 distorted trigonal pyramid (the average 〈Ag3–S〉 distance is 2.542 for 1 and 2.539 Å for 2) combined with trigonal Sb1S 3 or As1S 3 coordination pyramids (〈Sb1–S〉 and 〈As1–S〉 are 2.438 and 2.259 Å, respectively). The thallium atom Tl1 is surrounded by eight S atoms forming a square anti-prism (〈Tl1–S〉: 3.393 for 1 and 3.356 Å for 2), while the coordination polyhedron of Tl2 can be described as a significantly distorted trigonal prism or as an extremely distorted octahedron (〈Tl2–S〉: 3.236 Å for 1 and 3.238 Å for 2). Thallium Tl3 is surrounded by six atoms (one Ag, four S at shorter and one S at longer distance), which form a distorted trigonal prism (〈Tl3–S〉: 3.165 Å in 1 and 3.155 Å in 2). The second slab consists of trigonal Sb2S 3 or As2S 3 coordination pyramids combined with Ag1S 4 and Ag2S 4 coordination tetrahedra (〈Sb2–S〉 and 〈As2–S〉 are 2.433 and 2.251 Å, respectively; 〈Ag1–S〉: 2.623 Å for 1 and 2.612 Å for 2; 〈Ag2–S〉: 2.623 Å for 1 and 2.630 Å for 2). The most interesting feature of both structures is the existence of short Tl3–Ag3 contacts of 2.959(2) Å in 1 and 2.922(1) Å in 2. These contacts are the shortest found so far and indicate very strong Tl–Ag interactions. They are discussed in terms of metallophilicity principle and relativistic effects. It is also pointed out that if only valence shell electrons are considered (Tl–Ag) 2+ group is isoelectronic with the (Hg–Hg) 2+ ion, therefore new examples of short Tl–Ag contacts could be expected.

Double molybdate Tl2Mg4(MoO4)3: Synthesis, structure, and properties

Single crystals of molybdate Tl2Mg2(MoO4)3 are grown, and its crystal structure is refined in an X-ray diffraction experiment (an automated diffractometer, MoKα radiation, 914 F(hkl) reflections, R = 0.0459). The crystal are cubic with a = b = c = 10.700(1) A, V = 1225.0(2) A3, Z = 4, space group P213. The mixed 3D framework of the structure is built of MoO4 tetrahedra and two types of corner-sharing MgO6 octahedra. Two types of thallium atoms occupy large interstices.

Synthesis of 2,6‐Bis(bis(2‐(methylthio)phenyl)phosphino)‐4‐methylphenol, a Novel Polydentate Ligand Containing Two Tripodal [S,S,P,O] Coordination Pockets; Crystal Structure of the Dimeric Thallium(I) Complex

AbstractThe reactions of bis(2‐(methylthio)phenyl)chlorophosphine (5a) (2 equivalents) with the O‐protected 2,6‐dilithio‐4‐methylphenol followed by acidic workup led to the isolation of 2,6‐bis(bis(2‐(methylthio)phenyl)phosphino)‐4‐methylphenol (2). Analogous reactions do not proceed if the sterically bulkier bis(2‐(tert‐butylthio)phenyl)chlorophosphine (5b) is used instead of 5a. Compound 2 is a topological analog of binucleading ligands built on a 2,6‐diaminophenol core, where two tripodal N‐ or O‐ligating compartments are flanking the phenolate functionality. A distinguishing feature of 2 is the “soft” donor environment of the potentially [S,S,P]‐ligating pockets flanking the phenolic OH group. Reaction of 2 with TlOEt lead to the formation of the dimeric thallium(I) phenoxide (3), which was characterized by a single crystal X‐ray diffraction study. In addition to μ‐phenoxide ligation, in the solid state each thallium atom also interacts with two phosphorus atoms from the opposing ligands. The interactions are not equivalent, with the two TlI–P distances differing by ca. 0.3Å. No significant Tl···S interactions are present in the solid state. Room temperature 31P NMR measurements indicate the dynamic behavior of 3 in solution.