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  • 1
    ISSN: 0009-2940
    Keywords: (Hydroxymethyl)diorganylsilanes, esters of ; Rearrangement, thermally induced ; Kinetics ; DSC ; Calculations, ab initio ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Esters of (Hydroxymethyl)diorganylsilanes: Synthesis and Thermally Induced RearrangementTwenty silanes of the type R1R2Si(H)CH2OR3 (A) were synthesized [R1, R2 = Me, Ph, 1-naphthyl, PhCH2,Me3SiCH2; OR3 = OC(O)Me, OC(O)Ph, OC(O)CF3, OS(O)2CF3, OP(O)Ph2, OC(O)Cl] and studied for their thermal behaviour. The silanes A undergo a thermally induced rearrangement to give the corresponding silanes R1R2Si(OR3)Me (B). For compounds with OR3 = OC(O)Cl, an additional decarboxylation takes place to yield the chlorosilanes R1R2Si(Cl)Me. Except for the derivatives with OR3 = OC(O)Cl, the energetic (reaction enthalpy) and kinetic data (reaction order, frequency factor, enthalpy and entropy of activation) of these reactions were studied by means of differential scanning calorimetry (DSC). In addition, the kinetics of all reactions were investigated by 1H-NMR spectroscopy. The transition state of the rearrangement was investigated by an ab initio study based on the model compound H3SiCH2OC(O)H [→ MeH2SiOC(O)H]. The theoretical data and the experimentally obtained energetic and kinetic data are discussed in terms of mechanistic aspects of the rearrangement reaction A → B.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0044-2313
    Keywords: Disulfonyl amines ; silver(I) 1,1,3,3-tetraoxo-1,3,2-benzodithiazolide ; aqua(1,1,3,3-tetraoxo-1,3,2-benzodithiazolido)silver(I) ; crystal structure ; thermal analysis ; calorimetry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polysulfonyl Amines. XLII. An Aquasilver(I) Complex with an Ag(m̈-H2O)2Ag Structural Unit: Characterization of Aqua(1,1,3,3-tetraoxo-1,3,2-benzodithiazolido)silver(I) by X-Ray Diffractometry and Thermal AnalysisThe title compound C6H4(SO2)2NAg · H2O, where C6H4(SO2)2Nº is the anion of 1,2-benzenedisulfonimide, crystallizes in the monoclinic space group C2/m with (at -95°C) a = 1 129,7(3), b = 1 196.1(3), c = 810.7(2) pm, β = 124.25(2)°, V = 0.9055 nm3, Z = 4, Dx = 2.524 Mg m-3. The crystal packing consists of [Ag(m̈-H2O)2Ag{m̈-C6H4(SO2)2N}2]n bands with crystallographic mirror symmetry, associated into layers by H-bonds with O(W) - O(S) 289.7 pm. The Ag(m̈-H2O)2Ag moiety forms a planar four-membered ring with Ag—O(W)—Ag 97.3°, O(W)—Ag—O(W) 82.7° and Ag°Ag 372.1 pm. In the Ag{C6H4(SO2)2N}2Ag′ unit, the anions act as tridentate (N, 1-O, 3-O)-ligands: One is N-bonded to Ag and O,O-chelated to Ag′, the other N-bonded to Ag′ and O,O-chelated to Ag. The silver atoms are (O4N)-pentacoordinate, with nitrogen in the apical position of a distorted square pyramid [Ag—N 223.6, Ag—O(W) 247.8, Ag—O(S) 259.4 pm]. The thermochemical behaviour of the hydrate was investigated by thermal analysis and calorimetry. Water is only released at temperatures above 220°C. The dehydration enthalpy at 298 K is + 13.9 kJ mol-1.
    Notes: Die Titelverbindung C6H4(SO2)2NAg · H2O, mit C6H4(SO2)2N- = Anion des 1,2-Benzoldisulfonsäureimids, kristallisiert in der monoklinen Raumgruppe C2/m mit (bei -95°C) a = 1 129,7(3), b = 1 196,1(3), c = 810,7(2) pm, β = 124,25(2)°, V = 0,9055 nm3, Z = 4, Dx = 2,524 Mg m-3. Die Kristallpackung besteht aus Strängen des Typs [Ag(m̈-H2O)2Ag{m̈-C6H4(SO2)2N}2]n mit kristallographischer Spiegelsymmetrie, die über H-Brücken mit O(W)…O(S) 289,7 pm zu Schichten assoziiert sind. Die Ag(m̈—H2O)2Ag-Einheit bildet einen planaren Vierring mit Ag - O(W) - Ag 97,3°, O(W) - Ag - O(W) 82,7° und Ag…Ag 372,1 pm. In der Ag{m̈—C6H4(SO2)2N}2Ag′-Einheit wirken die Anionen als dreizähnige (N, 1-O, 3-O)-Liganden, und zwar das eine als N-Donor gegenüber Ag und als O,O-Chelatligand gegenüber Ag′, das andere umgekehrt als N-Donor gegenüber Ag′ und als O,O-Chelatligand gegenüber Ag. Die Silberatome sind (O4N)-pentakoordiniert mit dem Stickstoffatom am Scheitelpunkt einer verzerrten quadratischen Pyramide [Ag—N 223,6, Ag—O(W) 247,8, Ag—O(S) 259,4 pm]. Das thermochemische Verhalten des Hydrats wurde mit thermoanalytischen und kalorimetrischen Methoden untersucht. Das Wasser wird erst bei Temperaturen oberhalb 220°C abgegeben. Die Dehydratationsenthalpie bei 298 K beträgt + 13,9 kJ mol-1.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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