Showing papers by "George M. Sheldrick published in 1980"
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TL;DR: In this paper, the unstable thionitrosyl fluoride, NSF, can be stabilized by its incorporation as a ligand in transition-metal complexes, and the struc- ture of the Co lI derivative is reported.
Abstract: Co(NSF)6I(AsF6) 2, M r = 827.17, mono- clinic, P2~/n, a = 13.105 (9), b'= 9.201 (7), c = 9-366 (6) A, fl = 90.43 (4) ° , U= 1129 A 3, Z = 2, D x = 2.432 Mg m -3, /t = 4.3 mm -~ (Mo Ka). R = 0. 104 for 1296 unique observed reflexions. The Co atom lies at the origin and is octahedrally coordinated. The S-N and S-F distances are much shorter than in free NSF, but the N-S-F angle is not greatly altered. Introduction. The unstable thionitrosyl fluoride, NSF, can be stabilized by its incorporation as a ligand in transition-metal complexes. We report here the struc- ture of the Co lI derivative. A preliminary note has
12 citations
TL;DR: In this article, the structure of the title compound has been determined from X-ray diffractometer data, and it is isostructural with the cobalt derivative with respect to the graphite derivative.
Abstract: Abstract The structure of the title compound has been determined from X-ray diffractometer data. It is isostructural with the cobalt derivative [1].
10 citations
TL;DR: In this article, the simultaneous 1,3-migration of a trimethylsilyl group from one nitrogen atom to another is demonstrated by the crystal structure determination of the products of two such reactions, with different substituent groups.
Abstract: Abstract N-Organylamino-N′,N′-bis(trimethyl)amino-fluoroorganylsilanes react with butyl-lithium to give the corresponding lithium salts. Further reaction of these lithium salts with fluorosilanes leads to the formation of the expected substituted compounds. Diaza-disilacyclobutanes are formed by thermal LiF elimination in THF. The simultaneous 1,3-migration of a trimethylsilyl group from one nitrogen atom to another is demonstrated by the crystal structure determination of the products of two such reactions, with different substituent groups.
8 citations
TL;DR: In this article, the spectral properties of (N,N -dimethylformamide) 4 H 2 (TeBr 6 ) have been investigated spectroscopically and the spectral data are consistent with the crystal structure of the compound in which short hydrogen bonds are present.
8 citations
TL;DR: The structure of the title compound (a = 1185.4, b = 1197.7, c = 1764.8 pm, β = 73.96°, space group P21/c) has been determined from X-ray diffractometer data as mentioned in this paper.
Abstract: The structure of the title compound (a = 1185.4, b = 1197.7, c = 1764.8 pm, β = 73.96°, space group P21/c) has been determined from X-ray diffractometer data. The molecule is structurally analogous to the tetraborate ion [B4O7]2-. The eight-membered ring is folded by 104° about the B - B vector. The boron atoms are more strongly bonded to the bridging oxygen [B-O(B) 139 pm] than to the other atoms [B-O(C) 155 pm, B-N 160 pm, B-Cl 182 pm].
8 citations
TL;DR: In this paper, the ring contraction of the lithium salts with formation of lithiated (fluorodiorganylsilyl) amino-substituted four-membered rings is observed in THF solution.
Abstract: Abstract l-(Fluorodiorganylsilyl)-2,2,4,4,6,6-hexamethyl-3-(trimethylsilyl)cyclotrisilazanes react with butyllithium to give the corresponding lithium salts. Ring contraction of the lithium salts with formation of lithiated (fluorodiorganylsilyl)amino-substituted four-membered rings is observed in THF solution. The dimerisation of these cyclodisilazanes with elimination of LiF is demonstrated by crystal structure determinations of three products. Monoclinic and triclinic crystalline modifications of one compound could be isolated.
TL;DR: In this paper, an ion was obtained from a reaction between MoCI 3 and NaSPh (1:5 molar ratio) in methanol, followed by treatment with NEt4C1, and was recrystallized from a methyl cyanide-diethyl ether mixture.
Abstract: [N(C2Hs)412[Mo202S2(S2)2], 2CsH20N+.Mo2 O2S~-, M r = 676.6, monoclinic, P2;/c, a = 13.485 (3), b = 1 4 . 3 5 4 ( 3 ) , c = 14. 749 (3) A, f l = 97.50 (2) °, U = 2830.2.3, 3, Z = 4, D x = 1.588 Mg m-3; final R = 0.0358 for 4025 reflexions. The anion contains two Mo v atoms, each with a terminal 0 2and an edge-on ($2) 2ligand, bridged by two S 2ligands, and has approximate C2~ (mm) symmetry. Introduct ion . The compound was obtained from a reaction between MoCI 3 and NaSPh (1:5 molar ratio) in methanol, followed by treatment with NEt4C1, and was recrystallized from a methyl cyanide-diethyl ether mixture. Intensities were collected from a crystal of average dimension 0.28 mm by a profile-fitting procedure (Clegg, 1981) with graphite-monochromated Mo Ka radiation (2 = 0.71069/k) and a Stoe-Siemens AED four-circle diffractometer. 4025 unique reflexions with 7 _< 20 < 60 ° and I >_ 20(I) were measured and corrected for absorption by an empirical method based on measurements of sets of 0567-7408/80/112784-03501.00 reflexions at different azimuthal angles (g = 1.31 mm-~; transmission factors range from 0.588 to 0.654). Cell dimensions were obtained from the diffractometer angles for 50 centred reflexions with 20 _< 20<_ 25°. The structure was solved by Patterson and Fourier methods, and refined to a minimum value of ~. wA 2 [A = l E o 1 IFcl; w -1 = o2(Fo)]. Anisotropic thermal parameters were refined for all non-H atoms. H atoms were assigned isotropic thermal parameters fixed at 1.3 times the equivalent isotropic value for the corresponding C atom. C--H lengths and H--C--H angles were constrained to 0.96 A and 109.5 °. The final R is 0.0358, with R w = (~ wA2/Y WF2o) ~/2 = 0.0291. Coordinates and derived bond lengths and angles are given in Tables 1 and 2.* * Lists of structure factors, H atom coordinates and anisotropic thermal parameters have been deposited with the British Library Lending Division as Supplementary Publication No. SUP 35466 (27 pp.). Copies may be obtained through The Executive Secretary, International Union of Crystallography, 5 Abbey Square, Chester CH 1 2HU, England. © 1980 International Union of Crystallography [ N (C 2H 5)4121Mo20 z 52($2)2] Table 1. Atomic coordinates (x 105) and equivalent isotropic thermal parameters (/k 2 x 104)
TL;DR: In this paper, a silyl-bridged tris(cyclodisilazane) was shown to be a fused ring system, and the mechanism of its formation was discussed.
Abstract: 1,3-Dilithio-5-trimethylsilyl-2,2,4,4,6,6-hexamethylcyclotrisilazane (1) reacts in a 1:2 molar ratio with difluorodimethyl- or trifluoromethylsilane to give substitution at the lithiated N atoms. The reaction of the bis(fluorodimethylsilyl)-substituted compound with more of 1 produces ring contraction, to form a silyl-bridged tris(cyclodisilazane). In the reaction of the bis(difluoromethylsilyl)-substituted cyclotrisilazane with more of 1, however, the title compound, a fused ring system, is formed. This compound has been characterised by crystal structure determination. The mechanism of its formation is discussed.
TL;DR: The structure of gold(III) oxychloride is also polymeric, with square planar co-ordination at the metal atom (by three oxygens and one chlorine) as mentioned in this paper.
Abstract: Of all metals, gold shows the least tendency to form simple compounds with oxygen; anhydrous gold(III) oxide was until recently unknown. We have successfully prepared single crystals of gold(III) oxide and gold(III) oxychloride large enough to permit structure determination by X-ray crystallography. Both preparations (1, 2) involve the heating in sealed quartz tubes of amorphous hydrated gold(III) oxide with perchloric acid and an alkali metal perchlorate — temperatures and pressures of the order of 250°C and 30 MPa are required. Small variations of reagent ratios, temperature and pressure result in different ratios of products and different crystal sizes. X-ray diffraction data for both compounds have been collected on an automated diffractometer, and both structures have been elucidated (3, 4). Gold(III) oxide exhibits the usual square planar coordination of the metal atom as shown here. The asymmetric unit (smallest unique group of atoms) consists of one gold and two oxygen atoms, one oxygen atom lying on a crystallographic two-fold axis. This oxygen atom (02 in the diagram) is co-ordinated to two gold atoms, the other, 01, is co-ordinated to three gold atoms. This is reflected in the stronger (shorter) Au-02 bond. A trans effect is observed, the Au-01 bond trans to 02 being longest. The extended polymeric structure is best seen as a stereoview (3). The structure of gold(III) oxychloride is also polymeric, with square planar co-ordination at the metal atom (by three oxygens and one chlorine); it also shows a trans effect, the AuO bond trans to Cl being longest.