Edgar Nachbaur

Force constants, vibrational assignment and equilibrium geometry for isocyanic acid

Abstract Harmonic and several cubic force constants for HNCO have been calculated from ab initio SCF wavefunctions by Pulays force method. An exceptionally large value of 1.1 aJ A−1 is predicted for the stretch-bend coupling constant fR1α (NC, HNC). Comparison is made between the force constants calculated for HNC, HNCO, and HNCH2. In agreement with previous CNDO/2 calculations a nonlinear NCO group has been calculated. The calculations strongly support the assignment of the observed vibrational frequency at 777.1 cm−1 to the out-of-plane vibration.

Mo scf calculations on isocyanates

Abstract Calculations on some isocyanates have been performed by means of semi-empirical MO methods (CNDO/2). The NCO group is found to be nonlinear, in agreement with recent experimental result. Energies, charge densities and bond indices are discussed in relation to the stability of these compounds.

Beiträge zur Chemie der Kohlensäurederivate, 3. Mitt.: Neue Synthesen von Tris(trimethylsilyl) cyanurat,N-Chlorsulfinylimid und Chlorcyan

Tris(trimethylsilyl)cyanurate (I) has been prepared in high yields by silylation of cyanuric acid with trimethylsilyl cyanide, as well as by the reaction of trichloroisocyanuric acid with trimethylsilyl cyanide or trimethylsilylsulfinylimide. The latter reactions, yielding Cl−CN and Cl−NSO resp. as the only by-products, are convenient methods for synthesizing these pseudohalogen-chloride compounds in a very pure state. Starting fromN-chlorocarbonyl isocyanateI is formed in high yields by a complex reaction with trimethylsilylsulfinylimide too. Based on IR, Raman and1H-NMR data the O-silyl structure ofI was confirmed. The formation of products with N-silyl or N,O-silyl structure was never observed.

Kristallstruktur von Monosilber(I)amidosulfat, AgSO3NH2

A crystal structure analysis of the colourless AgSO3NH2 was carried out at room temperature:M=203.95, orthorhombic, Pcab,a=7.809 (2) Å,b=8.067 (2) Å,c=11.682 (3) Å,V=735.9 Å3,Z=8,dx=3.681 Mgm−3,F(000)=760, Mo Kα, λ=0.71069 Å (graphite monochromator), μ=5.77 mm−1,R=4.36% (509 reflections, 56 parameters). The ionic structure shows approximate trigonal bipyramidal coordination around the Ag+-ions.

Kristallstruktur von Trimethylisocyanursäure, (CH3NCO)3, und von Trichlorisocyanursäure-1/2-Ethylenchlorid, (ClNCO)3·1/2C2H4Cl2

X-ray crystal structure analyses of (CH3NCO)3 (M) and (ClNCO)3·1/2C2H4Cl2 (C) were carried out at room temperature (MoKα, graphite monochromator, λ=0.71069 Å): 1.M=171.16, monochlinic, P21/c,a=14.848 (1) Å,b=13.400 (2) Å,c=8.149 (1) Å, β=100.87 (1)°,V=1 592.3 Å3,Z=8,F(000)=720,dx=1.428 Mgm−3, μ=76m−1,R=6.51%,Rw=7.01% (964 reflections, 218 parameters). 2.M=281.89, monochlinic, P 21/c,a=9.416 (3) Å,b=5.728 (1) Å,c=18.199 (8) Å, β=98.64 (2)°,V=970.4 Å3,Z=4,F(000)=556,dx=1.929 Mgm−3, μ=1.11 mm−1,R=3.96%,Rw=3.44% (605 reflections, 132 parameters). The ring systems together with the C atoms of the methyl groups in (M) and with the Cl atoms in (C) are planar and have D3h-symmetry. Bond lengths and bond angles are discussed with regard to14N-NQR,35Cl-NQR and vibrational spectroscopic data.

Eine unerwartet stabile Sulfensäure: 4,6-Dimethoxy-1,3,5-triazin-2-sulfensäure; Synthese, Eigenschaften, Molekül- und Kristallstruktur / Unexpectedly Stable Sulfenic Acid: 4,6-Dimethoxy-1,3,5-triazine-2-sulfenic Acid; Synthesis, Properties, Molecular and Crystal Structure

4,6-Dimethoxy-1,3,5-triazine-2-sulfenic acid (1) was prepared by the reaction of 4,6-dimethoxy-1,3,5-triazine-2(1H)-thion (3) with 2-benzenesulfonyl-3-(p-nitrophenyl)-oxaziridine (2) in THF solution and isolated as a stable crystalline solid. The new compound was characterized by analytical and spectroscopic data (IR, 1H and 13C NMR, UV, MS) supported by MNDO-PM 3 calculations. UV spectrometry was used for exact determination of the ionization constant of 1(pKa = 5.86 ± 0.02 at 20°C). According to 13C NMR data and X-ray analysis the sulfenic acid 1 adopts the sulfenyl structure (R—SOH) in the condensed phase. Crystal data of 1 (90 K): a = 8.418(3), b = 21.289(6), c = 4.411(1) Å, Z = 4, P 21212, R = 0.0304, Rw = 0.0354 for 4105 unique reflections and 122 parameters. In the crystal, the molecules form dimers by two strong intermolecular O—H ••• N hydrogen bonds. The 6-membered ring shows alternating C—N bond lengths and is almost planar. The experimental electron deformation density (EDD) decreases in the order C—N > C—O ≈ C—S > S—O and is described in detail for the vicinity of the S atom.

Kristallstruktur von Sulfamid, SO2(NH2)2

X-ray crystal structure analyses of sulfamide were carried out at 293 K and at 100 K:M=96.10, orthorhombic, Fdd2,Z=8,F(000)=400, Mo Kα, λ=0.71069 Å (graphite monochromator). A) 293 K:a=9.127 (1) Å,b=16.857 (5) Å,c=4.579 (1) Å,V=704.50 Å3,dx=1.812 Mgm−3, μ=0.648 mm−1,R=1.77%,Rw=1.94% (384 reflections, 33 parameters). B) 100K:a=9.059 (1) Å,b=16.780 (8) Å,c=4.517 (1) Å,V=686.63 Å3,dx=1.859 Mgm−3, μ=0.665 mm−1,R=1.78%,Rw=1.95% (404 reflections, 33 parameters). The sulfamide molecule shows at 293 K S-O and S-N distances of 1.429 (1) Å and 1.620 (1) Å, respectively, which are in agreement with IR data. Hydrogen positions could be determined from differenceFourier syntheses. Strong weakening of some intense low order reflections by extinction was observed, their anisotropy depends on the crystal and on temperature.

Cyclotrisulfimide - Synthesis and Properties

Abstract Cyclotrisulfimide (1,3,5,2,4,6- trithiatriazine-1,1,3,3,5,5-hexoxide) (1) has been synthesized successfully from persilylated sulfanuric acid (2) and hydrogen chloride in dichloromethane and has been isolated in pure form. Correlations of infrared and 15N-NMR spectra support assignment of the imide structure of (1). Ring cleavage appears to characterize reactions of (1) with solvolytic reagents. Thermal decomposition of (1) has been studied by TG accompanied by TLC methods. Reaction with diazomethane in dioxane yields the N,N,N-trimethyl derivative (3). Hitherto unknown (2) has been prepared from the trisilver salt of (1) using uimethylchlorosilane. The compound (2) has been characterized by IR, 15N-NMR and by X-ray crystallography. In the structure the S3N3 ring adopts a flattened chair conformation with the silyl groups being axial.

(Nitrito-O, O')bis(triphenylphosphine-P)-silver(I) dichloromethane solvate

In the title complex, [Ag(NO2){(C6H5)3P}2].CH2Cl2, the Ag+ cation exhibits a tetrahedral coordination built up by the two O atoms of the anion [Ag—O 2.386 (3) and 2.481 (3) A] and the two P atoms of the ligands [Ag—P 2.4120 (12) and 2.4401 (12) A], and lies within the plane of the anion [N—O 1.253 (4) and 1.259 (4) A, and O—N—O 114.1 (3)°].

Darstellung und thermische Zersetzung von Lithiumcyanuraten Eine einfache Methode zur Gewinnung von wasserfreiem Lithiumcyanat

The formation of mono-, di- and tri-lithium cyanurate by reaction of LiOH or Li2CO3 with cyanuric acid has been investigated as a solid state reaction and by using high boiling alcohols as reaction medium. For investigating the solid state reactions thermoanalytical methods were used. The reaction with LiOH proceeds in two steps yielding trilithium cyanurate at 400°C. Under the same conditions only dilithium cyanurate is formed by reaction with Li2CO3. Lithium cyanate is obtained in high yields by thermolysis of trilithium cyanurate at 550°C. This procedure is therefore a simple method in synthesizing pure anhydrous lithium cyanate.ZusammenfassungDie Darstellung von Mono-, Di- und Tri-Lithiumcyanurat durch Umsetzung von Cyanursäure mit LiOH bzw. Li2CO3 in hochsiedenden Alkoholen und durch lösungsmittelfreie Festkörperreaktion wird beschrieben. Die Festkörperreaktionen werden mit Hilfe thermoanalytischer Methoden untersucht. Die Reaktion mit LiOH erfolgt in zwei Schritten und ergibt bei 400°C. Trilithium-cyanurat. Unter denselben Bedingungen wird mit Li2CO3 nur Dilithium-cyanurat gebildet. Die Thermolyse von Trilithium-cyanurat bei 550°C liefert in hoher Ausbeute Lithiumcyanat und stellt somit eine einfache Methode zur Darstellung dieser Verbindung in wasserfreier Form dar.