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Journal ArticleDOI

Synthesis and structure of the isomorphous bromo- and chlorodiethyldithiocarbamatotellurium(II), Te{(C2H5)2NCS2}X (XBr, Cl)

01 Jun 1996-Polyhedron (Pergamon)-Vol. 15, Iss: 18, pp 3123-3128
Abstract: Bromo- and chloro-susbtituted tellurium(II) dithiocarbamate complexes were prepared by the reaction of iododiethyldithiocarbamatotellurium(II), dissolved in dichloro-methane, with a suspension of their respective silver halide. The structure determination reveals the orthorhombic crystals of the complexes to be isomorphous, having halide-bridged polymeric structures. The polymeric chain adopts a helical configuration with the period of the helix being the length of the a -axis. Each tellurium has a TeS 2 X 2 coordination. The TeBr and TeCl distances observed in the complexes are 2.867(3) and 2.686(2) A, respectively and this structure is similar to that of Te{(C 2 H 5 ) 2 NCS 2 }I.
Topics: Dithiocarbamate (51%)
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Abstract: A survey of the crystallographic literature of tellurium(II)/(IV) 1,1-dithiolates (dithiocarbamate, xanthate, dithiophosphate, or dithiophosphinate) is presented. Coordination numbers range from a low of three in some organotellurium(II) 1,1-dithiolates to a high of eight in the binary tellurium(IV) dithiocarbamates. The coordination geometries are rich and varied due to the stereochemical influence exerted by up to two lone pairs of electrons and the penchant of tellurium to increase its coordination number by forming secondary Te⋯X interactions, where X = sulphur, halide, tellurium, oxygen, and, in one case, a π system defined by a four-membered TeS2C chelate. Stereochemical roles of the lone pairs of electrons are always evident in the tellurium(II) structures. By contrast, a stereochemical position is not always evident for the lone pair of electrons in the tellurium(IV) derivatives, in particular in circumstances where the tellurium centre has a high coordination number. Supramolecular aggregation mediated by Te⋯X secondary interactions often leads to the formation of dimeric aggregates but sometimes to supramolecular polymers, and rarely three-dimensional networks. Comparisons between closely related structures clearly indicate that the dithiocarbamate ligand is a more effective chelating ligand compared with the other 1,1-dithiolate ligands covered in this survey. This difference in coordinating ability is clearly correlated with the observation that non-dithiocarbamate structures are more likely to form high-dimensional supramolecular architectures.

38 citations

Journal ArticleDOI
06 Feb 2008-Polyhedron
Abstract: The reaction of organo(heterocyclic)tellurium(IV) derivative: C8H8TeI2(1,3-dihydro-2λ4-benzotellurole-2,2-diyl diiodide) with NH4S2CNC5H10 (ammonium piperidine dithiocarbamate) gives C8H8Te(S2CNC5H10)2 (1) and Te(S2CNC5H10)2 (2) or C8H8TeI(S2CNC5H10) (5) according to the reaction conditions. In such type of metathetical reactions, the formation of 2 is unprecedented and it corresponds to the first Te–C cleaved product. The reaction of 2 with CH3I, yields the oxidative addition product, CH3TeI(S2CNC5H10)2 (8). The formation of 2 is also supported through Quantum Chemical calculations. Another Te–C bond cleaved product TeI2[(C13H10N2S)2] · 4C4H8TeI2 (9) is obtained in the reaction of C4H8TeI2 (1,1,2,3,4,5-hexahydro-1,1-diiodotellurophene) with NH4S2CNHC6H5 (ammonium aniline dithiocarbamate). The reaction of 1,1,2,3,4,5,6-heptahydro-1-iodo-1-(morpholine dithiocarbamato) tellurane [C5H10TeI(S2CNC4H8O)] (10) with 1,10-phenanthroline gives an unusual product C12H8N2 · C4H10INO (11). The structures of the new complexes 2, 8, 9, 10 and 11 have been determined by the X-ray analysis.

12 citations

Journal ArticleDOI
Abstract: The ternary complexes [Pd(RaaiX)(SS)ClO4) where RaaiX is a N(1)-alkyl-2-(arylazo)imidazole (p-RC6H4N =NC3H2NN(1) X; X = Me, or Et, and R = H, Me or Cl) and SS = N,N-diethyldithiocarbamate or morpholinedithiocarbamate have been prepared and characterized by elemental analysis, i.r., u.v.-vis. and 1H-n.m.r. data. Electrochemical studies show azo reduction. The complexes are thermally unstable and decompose to bis(dithiocarbamato)palladium(II) in solution.

10 citations

Journal ArticleDOI
Abstract: Since the author's last surveys of this field in 1983 and 1987,1,2 there has been considerable developments in the structural chemistry of tellurium. A comprehensive review covers the field through most of 1993.3

8 citations

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01 Jan 1939-

14,243 citations

Journal ArticleDOI
Abstract: Anomalous scattering factors Δf′ and Δf″ have been calculated relativistically for Cr, Fe, Cu, Mo, and Ag Kα radiations for the atoms Li through Cf. An interpolation scheme for other wavelengths is included in a separate report. Relativistic calculations of the photoelectric cross section have been made and the integral for the principal contribution to Δf′ has been evaluated numerically without approximation to the form of the cross section‐vs‐energy curve, as has been done in previous calculations. Many of the results are significantly different from previous calculations. Where experimental values exist, agreement for Δf″ is improved. For the rare gases, except for xenon, agreement between Δf′ and experiment is improved. Because of the more rigorous evaluation of Δf′ from cross‐section information, it is presumed that the present Δf′ values are more accurate than previous calculated values. Calculated mass absorption coefficients for the elements are included as incidental information.

2,682 citations

Journal ArticleDOI
TL;DR: A computer program, ABSORB, has been written for correcting the observed structure factors using the differences obtained in the last cycle of the isotropic refinement, to model an absorption surface as a Fourier series in the polar angles of incident and diffracted beams.
Abstract: Absorption effects represent the most important source of systematic errors in X-ray diffraction experiments from a single crystal. The method of Walker and Stuart (1983) has proved to be a very useful tool for correcting the observed structure factors from absorption effects in crystal structure analyses, and give rise to increasing interest in the crystallographic community. Based on this method a computer program, ABSORB, has been written for correcting the observed structure factors using the differences |Fhkl0-Fhklc| obtained in the last cycle of the isotropic refinement, to model an absorption surface as a Fourier series in the polar angles of incident and diffracted beams. The program is quite general, but the input file of uncorrected observed structure factors and the output file of corrected observed structure factors are adapted for operating in conjunction with the SHELX (Sheldrick, 1976) package of crystallographic computer programs. The modifications necessary to adapt the program for operating in conjunction with any other crystallographic package are described. ABSORB has been applied by many crystallographers to correct for absorption effects in organic and inorganic compounds; some of the results obtained are reported here in synthetic form.

214 citations