STEREOCHEMSTRY OF ARSENIC: PART III. o-PHENYLENEDIARSINE OXYCHLORIDE

1962 ◽  
Vol 40 (6) ◽  
pp. 1113-1117 ◽  
Author(s):  
W. R. Cullen ◽  
J. Trotter

Crystals of o-phenylenediarsine oxychloride, C6H4As2Cl2O, are monoclinic with four molecules in a unit cell of dimensions a = 14.50, b = 8.38, c = 7.66 Å, β = 105.8°, space group C2/c. The structure has been determined from projections along the b and c axes. Each molecule is situated on a 2-fold symmetry axis and is planar except for the chlorine atoms, which lie one on either side of the plane of the other atoms. The values of the bond lengths and valency angles have been obtained. Abnormal valency angles at the arsenic and oxygen atoms are the result of their presence in the five-membered ring, and the unusual stability of the molecule in spite of these angles can be interpreted in terms of aromatic character, involving dπ–pπ bonding. The intermolecular separations correspond to normal van der Waals interactions.

1963 ◽  
Vol 41 (12) ◽  
pp. 2983-2987 ◽  
Author(s):  
W. R. Cullen ◽  
J. Trotter

Crystals of bis(diphenylarsenic) oxide are monoclinic, with four molecules in a unit cell of dimensions a = 11.48, b = 30.2, c = 5.97 Å, β = 93.8°, space group P21/n. The structure has been determined from projections along the a and c axes, using Fourier and difference syntheses. The As—O—As angle is 137°, the increase from the normal oxygen valency angle probably being a result of pπ—dπ bonding involving arsenic 4d orbitals. The As—O distance is 1.67 Å, and all the other bond lengths and angles are normal. The orientations of the substituent phenyl groups have been determined.


1963 ◽  
Vol 41 (1) ◽  
pp. 14-17 ◽  
Author(s):  
J. Trotter

Crystals of tri-p-tolylarsine are rhombohedral, with cell dimensions a = 9.84 Å, α = 80° 2′, and space group [Formula: see text]. There are two molecules in the unit cell, and hence the molecule has symmetry C3. The structure has been determined from a projection along the rhombohedral cell axis, and the bond lengths and valency angles are given. In comparison with an ideal model having maximum interaction between the arsenic lone pair and the aromatic π-electrons, each ring is rotated about its As—C bond by 36°, the three rotations being in the same sense. These displacements increase overcrowded distances in the ideal model to about the normal van der Waals separations, the closest intramolecular contacts between p-tolyl groups being [Formula: see text] and [Formula: see text]. All the intermolecular contacts correspond to van der Waals interactions.


1974 ◽  
Vol 52 (14) ◽  
pp. 2531-2541 ◽  
Author(s):  
Steven J. Rettig ◽  
James Trotter ◽  
W. Kliegel

Crystals of 4,4-dimethyl-2,2-diphenyl-1,3-dioxa-4-azonia-2-boranatacyclopentane are orthorhombic, a = 17.043(3), b = 6.289(1), c = 13.024(2) Å, Z = 4, space group Pna21. The structure was determined by direct methods, and was refined by full-matrix least-squares procedures to R = 0.071 for 1100 reflections with I ≥ 3σ(I). Bond angles in the five-membered ring, which has a distorted half-chair conformation, range from 101.5(4) for OBO to 107.1(4)° for NOB. Bond lengths are: mean B—C, 1.632(8), B—O, 1.506(7) and 1.556(8), N—O, 1.409(5), C—O, 1.378(9), C—N, 1.467–1.509(7–10), mean C—C(aromatic), 1.395(25) Å. The structure consists of discrete molecules separated by normal van der Waals distances.


1978 ◽  
Vol 33 (8) ◽  
pp. 881-883 ◽  
Author(s):  
Wolfgang May ◽  
Hans Georg von Schnering

Abstract By the weak acid interaction of polymeric phosphanes the condensation of ethylendi-amine yields in a small amount bicyclo-[4,4,0]-1,4,6,9-tetraazadecane C6H14N4. The compound crystallizes triclinic in the space group P1̅ with a = 841.6 pm, b - 463.6 pm, c = 529.2 pm, a= 109.05°, β= 108.35°, γ = 84.13° and Z= 1 formula unit per unit cell. The two condensed six-membered rings have chair conformations. The mean N-C bond lengths are 146.0 pm, the bridging C-C bond is 150.3 pm, whereas the other C-C bonds are 155.1 pm. Structure and condensation reaction are discussed.


2004 ◽  
Vol 59 (9) ◽  
pp. 985-991 ◽  
Author(s):  
Sabine Strobel ◽  
Thomas Schleid

Quaternary strontium copper(I) lanthanoid(III) selenides are formed by the oxidation of elemental strontium, copper and the corresponding lanthanoid with selenium. Orange to red needle-shaped single crystals of SrCuPrSe3 and SrCuCeSe3 have been synthesized by heating mixtures of Sr, Cu, Pr / Ce and Se with CsI as a flux in evacuated silica tubes to 800°C for 7 d. Both compounds crystallize orthorhombically in space group Pnma with four formula units per unit cell, but with unlike lattice constants (a = 1097.32(6), b = 416.51(2), c = 1349.64(8) pm for SrCuPrSe3 and a = 846.13(5), b = 421.69(2), c = 1663.42(9) pm for SrCuCeSe3) and therefore different structure types. The Pr3+ cations in SrCuPrSe3 are surrounded octahedrally by six Se2− anions forming chains of edge-sharing [PrSe6]9− octahedra that are joined by common vertices. Together with [CuSe4]7− tetrahedra they form [CuPrSe3]2− layers piled up parallel (001). Between those layers the Sr2+ cations are coordinated by seven Se2− anions in the shape of capped trigonal prisms linking the structure in the third dimension. On the other hand in SrCuCeSe3 the Ce3+ cations as well as the Sr2+ cations adopt a coordination number of seven. Since the bonding distances between cerium and selenium match with those of strontium and selenium the two crystallographically independent sites of these cations are occupied statistically by Ce3+ and Sr2+ with equal ratios. Nevertheless, there is a close structural relationship between SrCuPrSe3 and SrCuCeSe3. Similar to SrCuPrSe3 where Cu+ and Pr3+ cations together with Se2− anions form [CuPrSe3]2− layers parallel (001), the Cu+ cations and [(Ce1/Sr1)Se7]11.5− polyhedra in SrCuCeSe3 build strongly puckered layers which are connected by (Ce2)3+/(Sr2)2+ cations. The copper selenium part in both compounds correlates as well, with [CuSe4]7− tetrahedra linked by common vertices to form [CuSe3]5− chains running along [010].


2007 ◽  
Vol 63 (3) ◽  
pp. o1184-o1185
Author(s):  
Xi-Zhao Wang ◽  
Li-Na Pang ◽  
Jun-Zhi Liu ◽  
Fang-Gang Sun ◽  
Jian-Wu Wang

In the title compound, C15H14Br2ClNO3S, all bond lengths and angles show normal values. The five-membered ring exhibits a twist conformation. The crystal packing is stabilized mainly by van der Waals forces.


1978 ◽  
Vol 56 (19) ◽  
pp. 2526-2529 ◽  
Author(s):  
Chung Chieh ◽  
Laura P. C. Lee ◽  
Cecilia Chiu

Dibromobis(thiosemicarbazide)mercury(II), HgBr2(tsc)2, is isostructural with dichlorobis-(thiosemicarbazide)mercury(II). The crystal is orthorhombic with a = 8.825(9), b = 8.587(11), c = 15.939(22) Å, Z = 4, space group Pbcn. Some bond lengths and angles are: Hg—Br = 2.860(4) Å, Hg—S = 2.45(1) Å, C—S = 1.76(4) Å and [Formula: see text]. In both HgCl2(tsc)2 and HgBr2(tsc)2, the configuration of the coordinated thiosemicarbazide (tsc) is the same as that of the free molecule. The ir and Raman (R) spectra for the complexes and tsc in the region 300–1600 cm−1 are very similar. The strong band at 800 (807 R) cm−1 in the tsc due to v(C—S) is shifted to 773 (796 R), 777 (796 R), and 660 (680 R) cm−1 for HgCl2−(tsc)2, HgBr2(tsc)2, and HgCl2(tsc) correspondingly. A strong band at 368 (R) cm−1 present uniquely for HgCl2(tsc) can be assigned to v(Hg—N), The halides in HgX2(tsc)2 are bonded to one mercury(II) ion and weakly bridged to a neighboring molecule with Hg … Cl = 3.250(3) Å and Hg…Br = 3.436(4) Å. As a result, two Raman bands due to Hg—X are expected. For HgCl2(tsc)2, the two Raman bands occur at 236 and 166 cm−1, whereas for HgBr2(tsc)2, one was observed at 190 cm−1 but the other was masked by lattice modes. In HgCl2(tsc), the two Hg—Cl bonds are different and bands at 220 and 190 cm−1 are assigned to v(Hg—Cl)t.


2019 ◽  
Vol 75 (3) ◽  
pp. 336-341
Author(s):  
Saravanan Raju ◽  
Ray J. Butcher ◽  
Harkesh B. Singh

The structures of the 18-membered diselenide-linked macrocycle 10,27-di-tert-butyl 11,28-dioxo-2,3,19,20-tetraselena-10,12,27,29-tetraazapentacyclo[28.4.0.04,9.013,18.021,26]tetratriaconta-1(30),4(9),5,7,13,15,17,21,23,25,31,33-dodecaene-10,27-dicarboxylate, C36H34N4O6Se4, and its precursor di-tert-butyl 2,2′-[diselane-1,2-diylbis(2,1-phenylene)]dicarbamate, C22H28N2O4Se2, are reported. The precusor to the macrocycle contains two tert-butyl phenylcarbamate arms connected to a diselenide group, with Se—C and Se—Se bond lengths of 1.914 (4) and 2.3408 (6) Å, respectively. The macrocycle resides on a crystallographic center of inversion in space group P\overline{1} with one molecule in the unit cell (Z′ = 1 \over 2). It contains an 18-membered macrocyclic ring with two diselenide linkages. In this macrocycle, there are two free and two protected amino groups.


2018 ◽  
Vol 171 ◽  
pp. 14006
Author(s):  
Volodymyr Vovchenko ◽  
Paolo Alba ◽  
Mark I. Gorenstein ◽  
Horst Stoecker

The quantum van der Waals (QvdW) extension of the ideal hadron resonance gas (HRG) model which includes the attractive and repulsive interactions between baryons – the QvdW-HRG model – is applied to study the behavior of the baryon number related susceptibilities in the crossover temperature region. Inclusion of the QvdW interactions leads to a qualitatively different behavior of susceptibilities, in many cases resembling lattice QCD simulations. It is shown that for some observables, in particular for χBQ11/χB2, effects of the QvdW interactions essentially cancel out. It is found that the inclusion of the finite resonance widths leads to an improved description of χB2, but it also leads to a worse description of χBQ11/χB2, as compared to the lattice data. On the other hand, inclusion of the extra, unconfirmed baryons into the hadron list leads to a simultaneous improvement in the description of both observables.


2007 ◽  
Vol 63 (11) ◽  
pp. o4213-o4213
Author(s):  
Liang-zhong Xu ◽  
Guang-Wei An ◽  
Xu-Dong Yang ◽  
Xu Yi

The title compound, C7H12O3, was synthesized as an intermediate for the synthesis of the selective broad-spectrum nonsystemic acaricide spirodiclofen (trade name Envidor). The cyclohexane ring adopts a chair conformation. The molecules pack in layers, with O—H...O hydrogen bonds connecting the layers on one side and only van der Waals interactions on the other side.


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