Maha Seshasayee

Bio: Maha Seshasayee is an academic researcher. The author has an hindex of 1, co-authored 1 publications receiving 4 citations.

Reactions of (diethyldithiocarbamato)halogenotellurium(II); crystal structures of R[Te{S2CNEt2}X2][R = NEt4, X = I; R = H(phen)2(phen = 1,10-phenanthroline), X = I or Br]

Abstract: The reactions of (diethyldithiocarbamato)halogenotellurium(II) with thiourea, benzimidazole-2-thiol, halides (Cl–, Br–, I–) and 1,10-phenanthroline (phen) have been studied. The products were principally characterized by elemental analyses, IR and 1H NMR spectroscopies. Novel anionic (diethyldithiocarbamato)dihalogenotellurate(II) complexes resulted from the reactions of Te(S2CNEt2)X (X = Br or I) with NEt4X (X = Br or I) and phen. The crystal structures of the complexes [NEt4][Te(S2CNEt2)I2], [H(phen)2][Te(S2CNEt2)I2] and [H(phen)2][Te(S2CNEt2)Br2] have been determined. In the anions tellurium is co-ordinated to two sulfur atoms of the dithiocarbamate in an almost isobidentate manner and to two halides in an overall planar trapezoidal geometry. In [NEt4][Te(S2CNEt2)I2] the two iodides are almost equidistant to tellurium with distances of 3.079(1) and 3.072(1)A, whereas in [H(phen)2][Te(S2CNEt2)I2] the two Te–I distances are 3.151(1) and 3.038(1)A and in [H(phen)2][Te(S2CNEt2)Br2] the two Te–Br distances are 2.911(1) and 2.986(1)A. In [H(phen)2]+ the proton is bound to one of the nitrogen atoms of a phenanthroline group and the two phen groups are held together by three hydrogen bonds, of which two are of the interesting type C–H ⋯ N.

Recent Developments in the Structural Chemistry of Tellurium with Sulfur and Selenium Containing Ligands

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

Synthesis, X-ray structural and spectroscopic study of [bis(1,10-phenanthrolinium)](1+) {3,3′-commo-bis-[η5-1,2-dicarba-(3)-nickel(III)-closo-dodecaborate]}(1-), [H(1,10-C12H8N2)2]+{NiIII[η5-(3)-1,2-B9C2H11]2}−

Abstract: A new compound comprising a Ni(III) di-carbollide cluster anion [H(Phen)2][Ni(B9C2H11)2], Phen = 1,10-phenanthroline, has been prepared and structurally characterized. Crystal data: C28H39B18N6Ni, M = 684.92, monoclinic, space group P21/n; unit cell parameters: a = 19.337(3) A, b = 6.9968(8) A, c = 25.630(4) A; β = 101.69(1)°; V = 3395.8(9) A3, Z = 4, dcalc = 1.340 g/cm3, T = 293 K, F(000) = 1412, μ = 0.602 mm−1. The structure was solved by the direct and Fourier methods and refined in the full-matrix anisotropic approximation (isotropic for hydrogen atoms) to final agreement factors R1 = 0.0372, wR2 = 0.0887 for 4136 Ihkl ⩾ 2σI from 5445 measured Ihkl (an Enraf-Nonius CAD-4 diffractometer, λMoKα, graphite monochromator, ω-scanning). The structure is built from [H(Phen)2]+ cations and [Ni(C2B9H11)2]− anions. The anions have a usual for commo-metal carboranes sandwich structure consisting of two icosahedra {NiC2B9} sharing a common Ni vertex. EPR technique shows that nickel ion has the electron state 3d7 with S = 1/2. The angular dependence of single-crystal EPR spectra was used to calculate g-factors (g1 = 2.0803, g2 = 2.0229 and g3 = 1.9810) and to assign principal values of the g-tensor to the directions in the crystal structure, in accord with which g1 is directed along the Cb-Ni-Cb axis, while the direction and the value of g2 is determined by a distortion introduced by the cation. The compound has been characterized by IR and Raman spectroscopy.