Crystal structure of potassium 2-thiobarbiturate

The crystal and molecular structure of potassium thiobarbiturate C₄H₃KN₂O₂S (C₄H₄N₂O₂S-2-thiobarbituric acid, H₂TBA) is determined. Crystallographic data for KHTBA are as follows: a = 11.2317(17) Å, b = 3.8687(6) Å, c = 14.557(2) Å, β = 97.448(4)°, V = 627.18(17) ų, space group P2/c, Z = 4. Each potassium ion is linked with four oxygen atoms and two S atoms forming a distorted octahedron. N-H…O and C-H…S hydrogen bonds form a branched three-dimensional network. The structure is also stabilized by the π-π interaction of heterocyclic HTBA^? ions.     

Crystal structure of catena-(2-thiobarbiturato) dithallium(I)

By powder X-ray diffraction the crystal structure of catena-(2-thiobarbiturato)dithallium(I) C₄H₂N₂O₂STl₂ (C₄H₄N₂O₂S is 2-thiobarbituric acid, H₂TBA), Tl₂TBA, is determined. Crystallographic data for Tl₂TBA are as follows: a = 15.1039(3) Å, b = 12.0818(2) Å, c = 3.86455(6) Å, β = 97.203(1)°, V = 741.34(2) ų, space group P2₁/n, Z = 4. There are two non-equivalent thallium atoms in the structure. The Tl1 polyhedron is a distorted trigonal prism due to the shortened Tl-S contact (3.634 Å), and the Tl2 polyhedron is a distorted square antiprism.     

Extraction separation of thallium (III) from thallium (I) with n-octylaniline

A novel method is developed for the extraction separation of thallium(III) from salicylate medium with n-octylaniline dissolved in toluene as an extractant. The optimum conditions have been determined by making a critical study of weak acid concentration, extractant concentration, period of equilibration and effect of solvent on the equilibria. The thallium (III) from the pregnant organic phase is stripped with acetate buffer solution (pH 4.7) and determined complexometrically with EDTA. The method affords the sequential separation of thallium(III) from thallium(I) and also commonly associated metal ions such as Al(III), Ga(III), In(III), Fe(III), Bi(III), Sb(III) and Pb(II). It is used for analysis of synthetic mixtures of associated metal ions and alloys. The method is highly selective, simple and reproducible. The reaction takes place at room temperature and requires 15-20 min for extraction and determination of thallium(III).     

Crystal structure of (acetylacetonato) (dicarbonyl)iridium(I)

The structure of Ir(CO)₂(acac) is determined by XRD at room temperature. Crystallographic data for C₇H₇IrO₄ are: a = 6.4798(5) ?, b = 7.7288(5) ?, c = 9.1629(10) ?, α = 105.738(2)°, β = 90.467(3)°, γ = 100.658(2)°, space group 1, P , V= 433.24(6) ?³, Z = 2, d _calc = 2.662 g/cm³, R = 0.0167. The structure is built of isolated mononuclear molecules. The central iridium atom has a square coordination environment formed by two oxygen atoms that belong to the acetylacetonate ligand and two carbon atoms of carbonyl groups. The average Ir-O and Ir-C bond lengths are 2.045(3) ? and 1.832(6) ? respectively. Molecules are stacked in such a way that the planes of coordination squares turn out to be parallel to the Ir...Ir distances between the nearest neighbors in the stack of 3.242 ? and 3.260 ?. Original Russian Text Copyright ? 2009 by K. V. Zherikova, N. V. Kuratieva, and N. B. Morozova __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 3, pp. 595–597, May–June, 2009.     

Cerimetric determination of thallium (I)

Summary The cerimetric determination of thallium(I) has been reinvestigated. A new procedure for the potentiometric titration of thallium(I) with ceric sulphate at the room temperature and at a low concentration of hydrochloric acid (1.0 N) has been developed using iodine monochloride as catalyst.The authors wish to express their grateful thanks to the Ministry of Education, Government of India, for the award of a Research Scholarship and the authorities of the Andhra University for providing research facilities.     

Crystal and molecular structure of (BEDT-TTF)4Cd2I6

The new radical-cation salt (BEDT-TTF)₄Cd₂I₆ has been studied by x-ray diffraction (a=19.284(6), b=12.84(1), c=7.869 (2) Å; α=72.77(4), β=94.44(2), γ= 103.97(3)^o, space group P1, Z=1, d_calc=2.32 g/cm³). The radical cation (BEDT-TTF)^1/2+ and the Cd₂I₆ ^2? anions form organic and inorganic layers alternating along the a axis. In the organic layer, (BEDT-TTF)^1/2+ are arranged in stacks and ribbons. The radical-cations in the ribbon are packed “side to side” and are joined to one another through shortened intermolecular contacts S...S 3.346(5)-3.657(4) Å. The Cd₂I₆ ^2? anion is dimeric. The Cd atom has a distorted tetrahedral bond configuration, with bond lengths Cd-I 2.722(l)-2.886(1) Å and valence angles I-Cd-I 93.8(1)-114.1(1)°.     

Dichrometric determination of thallium (I)

Summary A dichrometric procedure has now been developed for the direct volumetric titration of thallium(I), to an iodine monochloride end point. The concentration of the hydrochloric acid must be at least 7.5 N at the end point.     

Dichromate titration of thallium(I)

The formal redox potentials of the thallium(III)-thallium(I) couple in different acids of varying strengths are reported. The minimum concentration of hydrochloric acid required for a direct titration of thallium(I) with potassium dichromate is 5M. Thallium(I) can be titrated directly with the primary standard oxidant, potassium dichromate, at room temperature, with ferroin as indicator, in 6M hydrochloric acid. Atmospheric oxygen must be excluded.     

Crystal and molecular structure of an eight-coodinate N-methyltetraphenylporphyrin complex: diacetato(N-methyl-meso-tetraphenylporphyrinato)thallium(III)

The crystal structure of diacetato(N-methyl-meso-tetraphenylporphyrinato)thallium(III), Tl(N-Me-tpp)(OAc)2 (1), was established, and the coordination sphere around the Tl3+ ion is described as an eight-coordinate square-based antiprism in which two cis chelating bidentate OAc- groups occupy two apical sites. The plane of the three pyrrole nitrogen atoms (i.e., N(1), N(3), N(4)) strongly bonded to Tl3+ is adopted as a reference plane 3N. The pyrrole N(2) ring bearing the methyl group (i.e., C(45)H3) is the most deviated one from the 3N plane, making a dihedral angle of 21.4 degrees, whereas smaller angles of 9.1 degrees, 7.1 degrees, and 0.9 degree occur with pyrroles N(1), N(3), and N(4), respectively. Because of its larger size, the thallium(III) ion Tl3+ is considerably out of the 3N plane; its displacement of 1.17 A is in the same direction as that of the two apical OAc- ligands. The intermolecular acetate exchange process for 1 in THF-d8 solvent is examined through 1H NMR temperature-dependent measurements. In the slow-exchange region, the methyl and carbonyl carbons of the OAc- groups in 1 are separately located at delta 18.6 [3J(Tl-13C) = 405 Hz] and 170.8 [2J(Tl-13C) = 334 Hz] at -80 degrees C, respectively.     

Polymeric lithium(I) diaquabarbiturate: Crystal structure

The lithium(I) catena-diaquabarbiturate complex [Li(H₂O)₂(HBA–O,O′)] _n (I), where Н₂ВА is barbituric acid, has been structurally characterized by X-ray diffraction (CIF file CCDC no. 1447689), and its thermal decomposition and IR spectrum have been studied. Crystals of complex I are monoclinic, a = 6.4306(7) Å, b = 16.720(1) Å, c = 7.1732(8) Å, β = 108.253(4)°, V = 732.5(1) ų, space group P2₁/c, and Z = 4. One independent μ₂-bridging HBA^– ligand is coordinated to two Li(I) ions via the two oxygen atoms of C₄₍₆₎=O carbonyl groups. Each Li⁺ ion is linked with two μ₂-HBA^– ions and two terminal water molecules at tetrahedron vertices. μ₂-HBA^– ions link tetrahedra into a chain. The structure is stabilized by multiple hydrogen bonds and π–π-interaction between HBA^–. The shift of ν(C=O) vibration bands in the IR spectrum of complex I in comparison with Н₂ВА towards lower frequencies agrees with the coordination of HBA^– via oxygen atoms. The dehydration of complex I occurs in two stages in the regions of 100–150 and 150–240°C.     

Crystal structure of mixed-ligand silver(I) hydrogen iminodiacetate

The crystal structure of mixed-ligand silver(I) hydrogen iminodiacetate has been studied. The composition of the [Ag₂(C₄H₆NO₄)(NO₃)(H₂O)] _n ([Ag₂(HIda)(NO₃)(H₂O)] _n ) coordination polymer has been refined. The NO₃ and H₂O ligands in the complex form rather weak coordination bonds with the Ag atoms. The system of hydrogen bonds in the structure has been considered. The formation of a chain of hydrogen bonds between the disordered H₂O molecules was established.     

Tetrachloroaurate(III) oxidation of thallium(I)

Summary The complementary reaction between Tl^I and AuCl _inf4 ^sup– was studied in a 3.0 mol dm^–3 HCl medium. The active species of oxidant and reductant were found to be HAuCl₄ and TlCl _inf2 ^sup– , respectively. A mechanism involving these reactive species is proposed, in agreement with the results obtained.     

Crystal structure of CF3I(Cl)F

In addition to CF3IF2 and CF3ICl2, CF3I(Cl)F is the only known example of the (trifluoromethyl)iodine dihalides. CF3I(Cl)F is even at low temperatures not stable in solution and decomposes by symmetrization. It crystallizes in the orthorhombic space group Cmca with a = 6.898(1) A, b = 7.310(1) A, c = 20.127(1) A and eight formula units per unit cell. The final R indices [I > 2 sigma(I)] are R1 = 0.0372 and wR2 = 0.0981.     

Aggregation behaviour of thallium(I) beta-diketiminates

Modulation of the steric requirements of a number of N-aryl beta-diketiminate ligands results in the isolation of a variety of Tl(I) compounds with different stabilities and nuclearities.     

Crystal structure of [Pt2I4(TEPOP)2] (TEPOP = tetraethyldiphosphite).

The structure of the dinuclear complex [Pt2I4(TEPOP)2] (TEPOP = tetraethyldiphosphite) was determined by X-ray diffraction. The two platinum atoms are doubly bridged by two (EtO)2POP(OEt)2 ligands and constitute an eight-membered ring. The platinum atoms have a square-planar geometry, which are completed by two phosphorous and two iodine atoms in a mutually cis arrangement.