Thallium Complexes Research Articles

Structurally characterized bimetallic porphyrin complexes of Pb, Bi, Hg and Tl based on unusual coordination modes

This minireview highlights the unusual coordination geometries observed in bimetallic complexes of mercury, thallium, lead and bismuth. These bimetallic complexes remain scarce and through an analysis of their X-ray structures, the various structural features that favorise them will be underlined.

Thallophilic Tl(i)-Tl(i) contacts mediated by Tl-aryl interactions. A computational study.

A computational study is presented of a complex of thallium with a neutral β-triketimine ligand which was found to form dimers with close Tl-Tl interactions. Single point energies, using the crystallographic structures, suggest that the system is bound only when BArF counter ions are included in the calculations. Energy decomposition analysis of the system was carried out in order to investigate the nature of the bonding. Across the methods, calculations show the electrostatic interaction to be repulsive for the dimer with no counter ions, but attractive when BArF counter ions are included. This suggests the metallophilic interaction is counter ion-mediated, requiring the anions to provide favourable electrostatics, even in the case of spatially diffuse and distant counter ions such as the 3,5-bistrifluoromethylphenyl borate ions used here.

Unusual coordination modes of ligand 2-chloro-5-nitrobenzene sulfonate: Synthesis, spectroscopic characterization, thermal and X-ray structural studies of metal 2-chloro-5-nitrobenzene sulfonate complexes, metal = Tl(I), Cu(II), Ag(I) and Pb(II)

Using metal ions thallium(I), copper(II), silver(I) and lead(II) and ligand 2-chloro-5-nitrobenzenesulfonate(cnb), four new metal complexes [Tl(cnb)]n(1), [Cu(en)2(H2O)2](cnb)2.2H2O(2), where en = ethylenediamine, [Ag(cnb)]n(3) and [Pb(cnb)2]n(4) have been synthesized and characterized by elemental analyses, spectroscopic methods (FT-IR, multinuclear NMR), single crystal X-ray structure analyses (except 4) and TGA analyses. Complexes 1 and 3 crystallize in monoclinic crystal system in P21/c space group having unit cell dimensions, a = 13.849(2) Å, b = 9.449(2) Å, c = 7.506(2)Å, β = 105.3°, V = 947.1 Å3, Z = 4 and a = 15.197(13)Å, b = 5.136(4)Å, c = 24.058(18)Å, β = 106.86°, V = 1797.1 Å3, Z = 4 respectively. Complex 2, crystallizes in triclinic crystal system with PI¯ having unit cell parameters; a = 6.888 Å, b = 7.835 Å, c = 13.227 Å, α = 80.20°, β = 83.15°, γ = 78.18°, V = 945.6 Å3, Z = 1. X-ray structure determination revealed that complexes 1 and 3 are polymeric in nature, whereas complex 2 has ionic structure. Remarkably, cnb ligand is coordinating through sulfonato oxygen atoms and nitro oxygen atoms in thallium complex but coordinates through sulfonato oxygen atoms and chloro group in silver complex, thereby showing the flexible/versatile coordinating behaviour of anionic ligand. This is unusual.

Organometallic Complexes of Bulky, Optically Active, C3-Symmetric Tris(4S-isopropyl-5,5-dimethyl-2-oxazolinyl)phenylborate (ToP*)

A bulky, optically active monoanionic scorpionate ligand, tris(4S-isopropyl-5,5-dimethyl-2-oxazolinyl)phenylborate (ToP*), is synthesized from the naturally occurring amino acid l-valine as its lithium salt, Li[ToP*] (1). That compound is readily converted to the thallium complex Tl[ToP*] (2) and to the acid derivative H[ToP*] (3). Group 7 tricarbonyl complexes ToP*M(CO)3 (M = Mn (4), Re (5)) are synthesized by the reaction of MBr(CO)5 and Li[ToP*] and are crystallographically characterized. The νCO bands in their infrared spectra indicate that π back-donation in the rhenium compounds is greater with ToP* than with non-methylated tris(4S-isopropyl-2-oxazolinyl)phenylborate (ToP). The reaction of H[ToP*] and ZnEt2 gives ToP*ZnEt (6), while ToP*ZnCl (7) is synthesized from Li[ToP*] and ZnCl2. The reaction of ToP*ZnCl and KOtBu followed by addition of PhSiH3 provides the zinc hydride complex ToP*ZnH (8). Compound 8 is the first example of a crystallographically characterized optically active zinc hydride. We tested its catalytic reactivity in the cross-dehydrocoupling of silanes and alcohols, which provided Si-chiral silanes with moderate enantioselectivity.

Structural conversion of cubane-type thallium complex to hexagon silver complex by solid-state mechanochemical reaction

Solid-state structural transformation of TlI supramolecular polymer comprised from cubane-type thallium complex of [Tl4(μ3-4-BN)4] (1) (4-HBN=4-hydroxy benzonitrile) to AgI coordination polymer with three nuclear units of [Ag3(μ3-4-BN)2(μ4-4-BN)] (2) has been studied upon mechanochemical reaction of compound 1 with AgNO3.

Chemisorption of gold(III) from solutions using thallium(I) diisobutyldithiocarbamate: Supramolecular structure and thermal behavior of the polymeric gold(III)-thallium(III) complex ([Au{S2CN(iso-C4H9)2}2][TlCl4]) n

Chemisorption of gold(III) from 2 M HCl using thallium(I) diisobutyldithiocarbamate via an ion exchange/redox process gives a polymeric gold(III)-thallium(III) complex of the formula ([Au{S2CN(iso-C4H9)2}2][TlCl4])n (I). Its supramolecular structure determined by X-ray diffraction (CIF file CCDC no. 1009388) comprises three structurally nonequivalent complex cations [Au{S2CN(iso-C4H9)2{2]+ (A, B, and C) and two nonequivalent [TlCl4]−-anions, both the cations and the anions being conformers. The isomeric cations are united through pairs of relatively weak secondary nonvalent Au⋯S contacts into zigzag polymer chains (⋯A⋯B⋯C⋯B⋯)n, with alternating nonequivalent [TlCl4]− anions on both sides. The thermal behavior of complex I was studied by simultaneous thermal analysis. The TG curve shows two steps of its weight loss. The first step involves thermal decomposition of the dithiocarbamate portion of the complex and [TlCl4]− with reduction of gold(III) to metallic gold and release of TlCl. The second step is due to evaporation of TlCl. The final thermolysis product of complex I is reduced metallic gold.

The first scorpionate ligand based on diazaphosphole.

The reaction of PhBCl2 with 1H-1,2,4-λ(3)-diazaphosphole in the presence of NEt3 gives a new scorpionate ligand, phenyl-tris(1,2,4-diazaphospholyl)borate (PhTdap). The coordination behaviour of this ligand toward transition and non-transition metals has been comprehensively studied. In the thallium(I) complex, Tl(PhTdap), κ(2)-N,N bonding supported with intramolecular η(3)-phenyl coordination has been observed in the solid state. Tl(PhTdap) also shows unusual intermolecular π-interactions between five-membered diazaphosphole rings and the thallium atom giving infinite molecular chains in the crystal. In the square planar complex [Pd(C,N-C6H4CH2NMe2)(PhTdap)], κ(2)-bonded scorpionate has been detected in both solution and in the solid state. For other studied compounds with the central metal ion Ti(IV), Mo(II), Mn(I), Fe(II), Ru(II), Co(II), Co(III), Ni(II) and Cd(II), the κ(3)-N,N,N coordination pattern was observed. Electronic properties of PhTdap and its ligand-field strength were elucidated from UV-Vis spectra of transition-metal species. The CH/P replacement on going from tris(pyrazolyl)borate to the ligand PhTdap causes a slight increase in electronic density rendered to the central metal atom. The following order of ligand-field strength has been established: HB(3,5-Me2pz)3 < PhB(pz)3 < HB(1,2,4-triazolyl) < HB(pz)3 < PhB(1,2,4-triazolyl) < PhTdap. The crystal structures of ten metal complexes bearing the new ligand are reported. The possibility of PhTdap coordination through the phosphorus atom is also briefly discussed.

1,4-Bis(2′-pyridylethynyl)benzene as a ligand in heteronuclear gold–thallium complexes. Influence of the ancillary ligands on their optical properties

The reaction of 1,4-bis(2'-pyridylethynyl)benzene (L) with [{Au(C6X5)2}Tl]n affords new heterometallic Au(I)/Tl(I) complexes with different stoichiometries, structural arrangements and optical properties depending on the halogens present in the aryl group. The chlorinated derivative [{Au(C6Cl5)2}Tl(L)]n () displays polymeric chains built thanks to unsupported AuTl interactions and bridging bidentate ligands between adjacent chains, while in the fluorinated species [{Au(C6F5)2}2Tl2(L)2]n (), also containing N-donor bridging ligands and AuTl contacts, polymerization occurs via TlCaryl non-bonding interactions between neighbouring molecules. The optical properties of and have been studied experimentally and theoretically, concluding that the luminescence of in the solid state has its origin in the AuTl interactions, and that the TlCaryl interactions in favour a non-radiative deactivation pathway that avoids luminescence. The strength of the non-bonding interactions present in has also been theoretically studied at the HF and MP2 levels, revealing the metallophilic contact as the strongest one.

Synthesis, characterization, single crystal X-ray structure determination and packing analysis of thallium(I) anthracene-9-carboxylate, [Tl4(H2O)2(anthracene-9-carboxylate)4

A new tetranuclear thallium complex, [Tl4(H2O)2(anthracene-9-carboxylate)4] was isolated by reaction of hot aqueous solution of thallium(1)sulphate with sodium salt of anthracene-9-carboxylic acid in water taken in appropriate stoichiometric ratio. The newly synthesized complex was characterized by elemental analysis, thermogravimetric analysis, spectroscopic studies (FT-IR, UV–Visible, and multinuclear NMR). Complex crystallizes in monoclinic crystal system with P21/n space group. X-ray crystal structure determination revealed the presence of neutral centrosymmetric tetranuclear complex which contains two symmetry independent thallium cations. Tl1 is four-coordinate and bonded to three different anthracene-9-carboxylate anions. The other thallium cation, Tl2, is three-coordinate, being surrounded by two carboxylate oxygen atoms from two different ligands; anthracene-9-carboxylate and a water molecule. The crystal lattice is stabilized by CH/OH⋯O hydrogen bonding and cation⋯π interactions.

Oxidative bond formation and reductive bond cleavage at main group metal centers: reactivity of five-valence-electron MX₂ radicals.

Monomeric five-valence-electron bis(boryl) complexes of gallium, indium, and thallium undergo oxidative M-C bond formation with 2,3-dimethylbutadiene, in a manner consistent with both the redox properties expected for M(II) species and with metal-centered radical character. The weaker nature of the M-C bond for the heavier two elements leads to the observation of reversibility in M-C bond formation (for indium) and to the isolation of products resulting from subsequent B-C reductive elimination (for both indium and thallium).

Detection of Oxidative Damage of Synthetic Oligonucleotides Caused by Thallium(III) Complexes

AbstractBiologically important short sequences of DNA were treated with Tl(III) complexes. The chloride complex releases the Tl(III) cation and therefore oxidizes DNA components and at concentrations higher than 50 nM cuts the strands. The cuts are well seen in the EQCM plots. The change in the strand structure is well seen at CD and UV‐Vis spectra. The chelate complexes of Tl(III) do not damage the DNA strands. The SERS spectra were particularly useful in demonstration of the chemical changes and orientation vs. the surface changes of particular groups in the strands after interaction with TlCl4−.

Structure and luminescence properties of trichloridothallium(III) complexes with phenanthroline derivatives

Two thallium(III) complexes, [Tl(5-mphen)Cl3(DMSO)] (1) and [Tl(5,6-dmphen)Cl3(DMSO)]·DMSO (2) were prepared from the reaction of TlCl3·4H2O with 5-methyl-1,10-phenanthroline (5-mphen) and 5,6-dimethyl-1,10-phenanthroline (5,6-dmphen) ligands in DMSO solvent through methanol diffusion. Their crystal structures were determined by the X-ray diffraction method. These complexes have a bidentate nitrogenous ligand and a DMSO molecule with three chloride anions attached to a Tl(III) metal in a distorted octahedral environment, where both complexes were crystallized in the same space group (\(P\overline{1}\)) and crystal system (triclinic). The 1H NMR data confirms the stability of the compounds in the DMSO moiety. The luminescence study revealed that their luminescence behaviour is varied in comparison with corresponding ligands, although the thallium complexes exhibit the same structure and the only difference is the number of the methyl group on the phenanthroline ligand. Interestingly, complex 1 demanded a considerable enhancement (nine times), in comparison with the related phenanthroline ligand, a well-known material for OLEDs.

Influence of the Cavity Size of Water-Soluble Cryptophanes on Their Binding Properties for Cesium and Thallium Cations

The binding properties of water-soluble cryptophane 1 toward cesium and thallium cations, in basic solution, have recently been reported. In this Article, we show that water-soluble cryptophane-222 (2), cryptophane-223 (3), and cryptophane-233 (4), bearing zero, one, and two propylenedioxy linkers, respectively, also efficiently bind these two cations under similar experimental conditions. Their binding properties are thoroughly studied by (133)Cs and (205)Tl NMR spectroscopy, while the binding constants are determined by isothermal titration calorimetry (ITC) experiments under various experimental conditions. Complexation of cesium and thallium is also evidenced by electronic circular dichroism (ECD) using the enantiopure MM-2 compound. This study reveals that the cavity size of the cryptophane is not the main parameter to observe efficient binding. In contrast, the number of phenolate moieties surrounding the cryptophane backbone seems to be pivotal for the complexation of these two cations. These results are important in the field of detoxification.

{Tris[3-(adamantan-1-yl)-5-isopropylpyrazol-1-yl-κN2]hydroborato}thallium(I): the scorpionate with the most bulk?

In the thallium(I) complex, [Tl(C48H70BN6)], of tris[3-(adamantan-1-yl)-5-isopropylpyrazol-1-yl]hydroborate, the most hindered scorpionate ligand, the Tl(I) ion is coordinated by three N atoms from the anionic tridentate chelating ligand [average Tl-N bond length = 2.522 (4) Å] in a distorted trigonal-pyramidal environment [average N-Tl-N angle around the Tl(I) ion = 76.4 (1)°]. This coordination geometry is compared with that of the reported Tl(I) complex of the super-hindered tris(7-tert-butylindazol-2-yl)hydroborate ligand.

Nanothallium(III) sulfide from dithiocarbamate precursors: Synthesis, single crystal X-ray structures and characterization

Nanothallium sulfide was formed from Tl(chmdtc)3(1), Tl(chedtc)3(2) and Tl(dchdtc)3(3) (where chmdtc=cyclohexyl methyl dithiocarbamate, chedtc=cyclohexylethyl dithiocarbamate, dchdtc=dicyclohexyl dithiocarbamate). Single crystal structures of the complexes are reported. The ease of formation was the highest for (3) and is in line with the longest mean Tl–S and thioureide C–N bonds observed for (3). The nano metal sulfide formed is spherical in nature and has been characterized by PXRD, EDX, TEM. Tl4S3 was stable up to 300°C. Thioureide stretching bands are observed at 1471, 1468, 1448cm−1 for (1), (2) and (3) respectively. Thioureide stretching band of (3) is significantly lower than others due to steric effect of cyclohexyl substituents. Thallium(III) complexes exhibit fully allowed charge transfer transitions(CT) which appeared as intense absorptions. 1H NMR shows that the α-CH and α′-CH3 protons are affected to a maximum effect on complexation. 13C NMR spectra show thioureide carbon signal around 200ppm.

Thallium(I) complexes of fluorinated bis- and tris(pyrazolyl)borate ligands: [H2B{3,5-(CF3)2pz}2]Tl and [HB{3,5-(CF3)2pz}3]Tl

X-ray crystal structural data at 100 (2) K for the thallium(I) complex of a fluorinated bis(pyrazolyl)borate, {bis[3,5-bis(trifluoromethyl)-1H-pyrazol-1-yl-κN(2)]borato}thallium(I), [Tl(C10H4BF12N4)], abbreviated as [H2B{3,5-(CF3)2pz}2]Tl, and the related tris(pyrazolyl)borate, {tris[3,5-bis(trifluoromethyl)-1H-pyrazol-1-yl-κN(2)]borato}thallium(I), [Tl(C15H4BF18N6)], abbreviated as [HB{3,5-(CF3)2pz}3]Tl, are reported. [H2B{3,5-(CF3)2pz}2]Tl features a two-coordinate Tl(I) atom with a bent geometry and a boat-shaped bis(pyrazolyl)borate ligand. It also has several additional inter- and intramolecular Tl···H and Tl···F contacts in the solid state. The tris(pyrazolyl)borate analogue [HB{3,5-(CF3)2pz}3]Tl has a trigonal-pyramidal thallium centre and features inter- and intramolecular Tl···F contacts.

Noncovalent Interactions of Metal Cations and Arenes Probed with Thallium(I) Complexes

The synthesis, characterization, and computational analysis of Tl(I) complexes bearing the bis(imino)pyridine scaffold, [{ArN═CPh}2(NC5H3)]Tl(+)(OTf)(-) (Ar = 2,6-Et2C6H33, 2,5-(t)Bu2C6H3, 4), are reported. The cations of these species showed long Tl-N and Tl-OTf distances indicating only weak or no ligand coordination. Computational analysis of the interactions between the Tl cation and the ligands (orbital populations, bond order, and energy decomposition analysis) point to only minimal covalent interactions of the cation with the ligands. The weak ligand-to-metal donation allows for additional interactions between the Tl cation and arene rings that are either intramolecular, in the case of 3, or intermolecular. From benzene or toluene, 4 crystallizes with inverted sandwich structures having two [{(2,5-(t)Bu2C6H3)N═CPh}2(NC5H3)]Tl(+) cations bridged by either benzene or toluene. A density functional computational description of these Tl-arene contacts required exchange-correlation functionals with long-range exchange corrections (e.g., CAM-B3LYP or LC-PBE) and show that Tl-arene contacts are stabilized by noncovalent interactions.

Equilibrium studies of thallium(I) complexes with cytidine 5′-monophosphate in different aqueous solutions of methanol

The protonation equilibria of cytidine 5′-monophosphate (CMP) and its complex formation with Tl(I) ion were studied over a wide pH range (1.5 to 10.5), using a combination of spectrophotometric and potentiometric methods at constant temperature (25°C), different methanol–water mixtures (0 to 50% v/v), and constant ionic strength (0.1moldm−3 sodium perchlorate). Least squares regression calculations are consistent with the formation of TlHL and TlL− species, where L2− represents the fully dissociated ligand. The protonation of CMP and the formation constants of the formed complexes in different media were analyzed in terms of Kamlet, Abboud, and Taft (KAT) parameters. A single-parameter correlation of the formation constants versus α (hydrogen-bond donor acidity), β (hydrogen-bond acceptor basicity) and π* (dipolarity/polarizability) are relatively poor in all solutions, but dual and multi-parameter correlations represent significant improvements with regard to the single-parameter model. Linear correlation is observed when the experimental formation constant values (in logarithm scale) are plotted versus the calculated ones, while the KAT parameters are considered. Finally, the results are discussed in terms of the effect of solvent on protonation and complexation.

Synthesis and structural characterization of tris(2-pyridonyl)methyl complexes of zinc and thallium: a new class of metallacarbatranes and a monovalent thallium alkyl compound

Tris(2-pyridonyl)methanes may be synthesized via the reactions of the respective 2-pyridone with CHX3 (X = Cl, Br) and K2CO3 in the presence of [Bu(n)4N]Br, followed by acid-catalyzed isomerization with camphorsulfonic acid. These compounds provide access to a new class of alkyl ligands that feature oxygen donors and are capable of forming metallacarbatranes and a monovalent thallium alkyl compound.

Thallium(I) Complexes of Cyano-Substituted Bispyrazolylborate Ligands

Two thallium scorpionate complexes: dihydrobis(3-phenyl-4-cyanopyrazolyl)boratothallium(I) (TlBpPh,4CN), C20H14BN6Tl and dihydrobis(3-tert-butyl-4-cyanopyrazolyl)boratothallium(I) (TlBp t-Bu,4CN), C16H22BN6Tl have been prepared and characterized by X-ray diffraction. Both compounds crystallize in monoclinic space groups, TlBpPh,4CN in P21/n with a = 4.2039(3) A, b = 26.2211(17) A, c = 16.611(1) A, β = 90.199(3)°, and TlBp t-Bu,4CN in P21/c with a = 13.8578(5) A, b = 9.6741(4) A, c = 14.2790(5) A, β = 95.141(2)°. The two complexes show similar structures with elongated metal–ligand bonds and intermolecular interactions between the metal ion and cyano substituents, allowing the potential construction of cyano-bridged coordination polymers.