Crystal structure of the synthetic analog of radtkeite Hg<Subscript>3</Subscript>S<Subscript>2</Subscript>Cl<Subscript>1.00</Subscript>I<Subscript>1.00</Subscript>

The results of structural studies of the synthetic analog of the radtkeite mineral Hg₃S₂Cl_1.00I_1.00 are analyzed. The crystal structure of the compound has been refined; the unit cell parameters are a _m = 16.827(4) , b _m = 9.117(1) , c _m = 13.165(5) , = 130.17(2)°, V = 1543.3(8) ³, space group C2/m, Z = 8, R = 0.0527. A possible transition a ₀ = a _m; b ₀ = a _m + 2c _m; c ₀ = –b _m to the pseudo-orthorhombic F cell previously determined for radtkeite, where one of the angles ( ₀ ) is slightly different from 90° (89.55°), has been found. Each sulfur atom in the structure is bonded to three mercury atoms, forming SHg₃ umbrellas with distances 2.240(6) –2.474(8) and angles HgSHg 94.7(2)°–102.9(2)°. The SHg₃ fragments are linked through Hg vertices to form corrugated [Hg₁₂S₈] layers. The halogen atoms lie inside and between the [Hg₁₂S₈] layers; the distances are Hg-Cl and Hg-I 2.783(7) , 2.961(7) , and 3.083(4) –3.311(3) , respectively.Original Russian Text Copyright © 2004 by N. V. Pervukhina, S. V. Borisov, S. A. Magarill, D. Yu. Naumov, V. I. Vasiliev, and B. G. NenashevTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 755–758, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Crystal structure of polymorphous modifications of Tm2S3 and related compounds

The role of symmetry in crystal structure formation is revealed for the polymorphous modifications of Tm₂S₃ and related compounds Tm₁₅S{ib22}, Tm₅S₇, and Tm₈S₁₁ using the procedure of selecting and analyzing closepacked planes with cationic, anionic, and combined motifs. The laws of mutual agreement between the cation and anion matrices determining the size of the unit cells are examined, and relationships between the specific cation volumes and symmetry are traced. Translated fromZhumal Strukturnoi Khimii, Vol. 39, No. 4, pp. 669–675, July–August, 1998.     

[Hg3]4+ Cation in Inorganic Crystal Structures

The crystal-chemical structure of the minerals and inorganic compounds kuznetsovite [Hg₃](AsO₄)Cl and terlinguaite [Hg₃][HgO₂]Cl₂, as well as [Hg₃]₃(AsO₄)₄ and [Hg₃]₂[HgO₂](PO₂ and their analogs, is considered from the viewpoint of the packing of large supramolecular atomic groups. The cationic layer of polyhedra around the large [Hg₃]⁴⁺ cations, alternating with the anionic layer of [HgO₂]^2-, (AsO₄)^3-, (PO₄)^3-, Cl^-, plays the major role in structure formation. Segregation of mercury cations of different valences possibly reflects the solid-state transformations occurring in nature and accompanied by mercury liberation.     

On the symmetry of iron(III) tris-acetylacetonate crystals

The crystal structure of iron tris-acetylacetonate is re-determined. Crystal data at 293 K are: a = 15.4524(5) Å, b = 13.5876(4) Å, c = 16.5729(7) Å, Z = 8; at 150 K: a = 15.2541(4) Å, b = 13.4451(3) Å, c = 16.4256(5) Å, Z = 8. The structure is molecular and comprises isolated molecules. The coordination polyhderon of iron is an almost regular octahedron, Fe-O bond lengths are 1.977–2.003 Å (293 K) and 1.982–2.006 Å (150 K). In the crystalline state, the molecules are arranged in layers, and iron atoms are located on a plane yielding an almost regular trigonal net with the Fe...Fe separations of 7.558–8.103 Å (293 K) and 7.472–8.017 Å (150 K). The adjacent layer is positioned exactly over the first one with a Fe...Fe distance of 8.303 Å (293 K) and 8.236 Å (150 K).     

Potential of X-Ray Diffractometry in Structure Identification of Holmium Polysulfides

A series of experiments have been carried out to synthesize holmium polysulfides at temperatures from 600 to 840°C and sulfur vapor pressures of (2.1, 6.5, 16.7)á10⁵ Pa. Polysulfide crystals sized up to 2 mm and micron-sized powders were investigated thereafter by powder diffractometry. Powder diffraction patterns were calculated based on our previous X-ray structural data. Characteristic reflections have been revealed for the individual monoclinic and tetragonal phases, and X-ray phase analysis (XRPA) has been performed for all batches of the synthesis. The monoclinic phase is shown to prevail irrespective of the synthetic conditions. The tetragonal phase was found in amounts of up to 10 wt.%.     

Crystal Structures of Two Re(V) Complexes of 3,5-Dimethylpyrazole with Linear and Bent [OReOReO]4+ Fragments

The crystal structures of two new dimer compounds of Re(V) containing an [OReOReO]⁴⁺ fragment have been studied. Re₂O₃Cl₄(3,5-Me₂pzH)₄ (I): space group P2¹/n, Z = 4, a = 10.180(3), b = 18.132(3), c = 16.601(2) , = 94.60(2)°, V = 3054.4(1) ³, d _calc = 2.059 g/cm³, R ₁ = 0.0513, wR₂ = 0.1493 for 4701 I_hkl > 2 _I of 4926 measured reflections; Re₂O₃Cl₂(-3,5-Me₂pz)₂(3,5-Me₂pzH)₂2[(3,5-Me₂pzH₂)Cl] (II): space group P2₁/n, Z = 4, a = 16.904(2), b = 14.573(1), c = 17.401(2) , = 107.23(1)°, V = 4094.2(7) ³, d _calc = 1.848 g/cm³, R ₁ = 0.025, wR₂ = 0.0514 for 6102 I_hkl > 2 _I of 6315 measured reflections (Enraf-Nonius CAD-4 diffractometer, MoK, graphite monochromator). Compound I has a molecular structure, where molecules are dimers Re₂O₃Cl₄(3,5-Me₂pzH)₄ with a bridging O atom. In II, the dominant motif is the ReOCl(3,5-Me₂pzH) fragments bridged by the pyrazole molecules and the O atom.     

Investigation of conjugated dinitrones — derivatives of pyrroline oxide

The molecular structure of three derivatives ofbis(2- R- 5,5- dimethyl- 3- oxo- 1- oxide pyrrolin- 1- ylidene- 3),where R =CH ₃ (@#@5a @#@), C ₆H₅ (@#@5b @#@), C(CH ₃)₃ (@#@5c @#@), and of the complex of 5b with copper(II)hexafluoroacetylacetonate [Cu(hfac) ₂ (@#@5b @#@)] was investigated by X- ray diffraction analysis in the framework of our studies of the possible tautomeric equilibrium conjugated dinitrone ? nitroxide biradical. The pyrroline rings of the molecules under analysis are planar (rms deviations of atoms are no more than 0.041 å), and the interplanar angles are 32.01(5), 42.84(9), and 51.45(7)? for 5a,5b,and 5c,respectively. It is established that the bond lengths of the C(2)- C(3) =C(3a)- C(2a) fragment are equalized to C(2)- C(3) 1.42 and C(3)- C(3a) 1.40 å. The N→O bond lengths of the nitrone group are within 1.250(4)- 1.282(4) å) [in Cu(hfac)₂ (5b)]. The geometrical data obtained do not permit us to make an unambiguous choice between the tautomeric structures. The magnetic susceptibility measurements of the Cu(hfac)₂ solid complex (5b) and the absence of paramagnetism in solid compounds 5 indicate that they are diamagnetic.     

Covalent Interactions in Mercury Oxohalides and Their Role in Crystal Structure Fragmentation

An [Hg₆O₂]-cationic (r) octahedron atomic group has been isolated in a number of mercury oxohalide structures. The octahedron is constructed from two edge-sharing oxo-centered [Hg₄O] tetrahedra. For -Hg₃O₂Cl₂, -Hg₃O₂Cl₂, Hg₂OI, [Hg₂]₃O₂Cl₂, [Hg₂]₃HgO₃Cl₂, Hg₅O₄Cl₂, and some other compounds, the geometrical parameters of their crystal structures depend on the dimensions and mutual packing of the cationic r-octahedra and the individual [Hg₄O] tetrahedra, if any.     

Complex of bis(hexafluoroacetylacetonato)copper(II) with a stable acyclic nitroxide (tert-butyl)(3-keto-2-methylbutyl-2) nitroxyl oxime

A complex of bis(hexafluoroacetylacetonato)copper(II) with a stable acyclic nitroxide (tert-butyl)(3-keto-2-methylbutyl-2)nitroxyl oxime (L), Cu(hfac)₂L, has been synthesized. The structure of the complex was studied by X-ray diffraction analysis. The compound has a molecular structure with chelate coordination of the nitroxide. The tetragonally distorted octahedral environment of the copper(II) ion is formed by the oxygen atoms of the hfac anions and by the nitrogen and oxygen atoms of the oxime and nitroxyl groups of L, respectively. The nitroxyl group lies in the equatorial plane of the octahedron (d_Cu?O=1.907 Å). This type of N?O coordination leads to strong antiferromagnetic exchange interactions between the unpaired electrons of the copper(II) ion and the coordinated nitroxyl group and, as a consequence, to diamagnetism of Cu(hfac)₂L.     

X-ray study of volatile Ni(II), Cu(II), and Pd(II) complexes of β-ketoimine pivalyltrifluoroacetone

Synthesis of volatile complexes based on -ketoimine pivalyltrifluoroacetone, C(CH₃)₃C(NH)CH₂COCF₃, is described. The general formula of the complexes is M(L)₂, where M = Cu, Ni, Pd. Complexes of this kind with Ni and Pd were obtained for the first time. The Cu and Pd complexes were found to be isostructural. A comprehensive crystal-chemical study showed that all structures are molecular and built of trans-complexes. The central atom has a square plane environment. The average M-O and M-N distances are nearly equal in all compounds: 1.84 , 1.92 , and 1.98 for Ni, Cu, and Pd complexes, respectively; the mean values of the O-M-N chelate angles are 93.4°, 91.9°, and 92.7°, respectively.Original Russian Text Copyright © 2004 by I. A. Baidina, G. I. Zharkova, N. V. Pervukhina, S. A. Gromilov, and I. K. IgumenovTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 713–722, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.