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  • 1
    Electronic Resource
    Electronic Resource
    13C-CP/MAS-NMR spectroscopy of tridentate diacidic ligands and their titanium(IV) chelates. molecular structure of bis[benzoylacetone thiobenzoylhydrazonato(2-)]titanium(iv) (1997)
    Springer
    Structural chemistry 8 (1997), S. 211-216 
    Details
    ISSN: 1572-9001
    Keywords: Titanium(IV) chelates ; tridentate diacidic ligands ; donor set ONO(S) ; 13C-CP/MAS-NMR spectra ; crystal structure of bis[benzoylacetone thiobenzoylhydrazonato(2-)]titanium(IV)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A series of tridentate diacidic ligands having the donor set ONO(S) as well as the corresponding titanium(IV) chelates were studied by13C-CP/MAS-NMR spectroscopy. Structural changes caused by the complex formation are discussed. The crystal structure of bis[benzoylacetone thiobenzo-ylhydrazonato(2-)]titanium(IV) was determined by X-ray analysis as to be distorted trigonal prismatic. Orthorhombic space group Pca2l,Z=4, 3304 observed independent reflections, unit-cell parameters at 298 K:a=22,808(2) å,b=13,073(4) å,c=10,450(4) å.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02263509
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  • 2
    Electronic Resource
    Electronic Resource
    Zur Interpretation 29Si-NMR-chemischer Verschiebungen (1973)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 5 (1973), S. 561-566 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The 29Si-NMR chemical shifts δ(29Si) of (CH3)4-nSiXn compounds and some 13C-NMR chemical shifts δ(13C) of analogous carbon compounds are discussed by means of relative paramagnetic screening constants σ*, calculated by a simplified model. In this model only the Si(3P)- and C(2P)-orbitals are considered; for the calculations, the electronegativities of Si, C and the X-substituents and a single empirical parameter are necessary. The calculated values of σ* are in good agreement with the change of the chemical shifts which are observed for the (CH3)4-nMXn compounds with different X and n. These results clearly show that δ(29Si) and δ(13C) depend primarily on the σ-charge of the Si- and C-atom, and that (P—d)π-interactions on the Si-atom are of minor importance.
    Notes: Zusammenfassung-die 29Si-NMR-chemischen Verschiebungen δ(29Si) einer größeren Zahl von Verbindungen des Typs (CH3)4-nSiXn sowie δ(13C) einiger analoger Kohlenstoffverbindungen werden mit Hilfe von relativen paramagnetischen Abschirmungskonstanten σ* diskutiert, die nach einem vereinfachten Berechnungsverfahren bestimmt werden. Für die Berechnung von σ* werden nur p-Orbitale berücksichtigt, als Ausgangsgrößen sind lediglilch die Elektronegativitäten von Si, C und X sowie ein einziger empirischer Korrekturfaktor erforderlich. Die berechneten Änderungen von σ* befinden sich in guter Übereinstimmung mit dem Gang der experimentellen Verschiebungen, die in den (CH3)4-nMXn-Verbindungen in Abhängigkeit von Zahl und Art der Substituenten X beobachtet werden. Die erhaltenen Ergebnisse zeigen, daß δ(29Si) und δ(13C) im wesentlichen durch die σ-Ladung am Si-bzw. C-Atom bestimmt werden und daß (p - d)π Wechselwirkungen am Si-Atom nur eine untergeordnete Bedeutung besitzen.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270051203
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  • 3
    Electronic Resource
    Electronic Resource
    A comment on the interpretation of 13C n.m.r. δ-syn-axial substituent effects in cyclic moleculesPart IV in the series ‘Stereochemical investigations by 13C-NMR’; for part III, see Ref. 1. (1976)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 8 (1976), S. 655-657 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An alternative explanation for δ-syn-axial substituent effects of 13C chemical shifts is given using the concept that the δ-syn-axial interaction in the substituted compound replaces the γ-gauche interaction in the parent molecule. The application of this principle to substituted norbornanes and steroids leads to the conclusion that the ‘net steric’ δ-syn-axial shift is upfield rather than downfield.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270081213
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  • 4
    Electronic Resource
    Electronic Resource
    29Si NMR spectra of methylphenylcyclotri-and -tetrasilazanes (1982)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 18 (1982), S. 71-73 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 29Si NMR spectra of various methylphenyl-substituted cyclotri- and -tetrasilazanes, composed of different combinations of the units d = Me2SiNH, dph = MePhSiNH and dph2 = Ph2SiNH, have been investigated. For most of the compounds having more than one asymmetric centre, the spectra of both the individual isomers and their mixtures have been studied, and the signals of the individual isomers have been assigned. The effect of a different arrangement of phenyl groups in the rings, and the influence of the stereochemistry of the isomers on the 29Si chemical shifts in cyclotri- and -tetrasilazanes have been studied. The 29Si chemical shifts in cyclotrisilazanes are additive and can be represented as the sum of increments corresponding to the number and positions of the phenyl groups in the rings. In these compounds, the spatial structure of the isomers does not exert any noticeable effect on the spectra. On the contrary, chemical shifts are not simply additive in cyclotetrasilazanes: a pronounced stereochemical dependence is apparent.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270180204
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  • 5
    Electronic Resource
    Electronic Resource
    Application of the attached proton test technique in 31P NMR spectroscopy (1984)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 22 (1984), S. 376-378 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intensity modulated 31P NMR spectra were obtained using the pulse sequence published by Patt and Shoolery. This attached proton test (APT) technique for signal assignment could be applied to systems with long-range heteronuclear couplings in P—O—C—H fragments. In a model system derived from the alcoholysis of P4S10 the six reaction products were assigned to the six signals in the 31P NMR spectrum.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270220606
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  • 6
    Electronic Resource
    Electronic Resource
    Gaschromatographische und 29Si-NMR-spektroskopische Untersuchungen an Kieselsäuretrimethylsilylestern (1976)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 424 (1976), S. 115-127 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Gaschromatographic and 29Si-NMR Spectroscopic Investigations on Silicic Acid TrimethylsilylestersSilicic acid trimethylsilylesters of different constitutions are characterized by gaschromatographic retention index and retention temperatures. It is shown that the retention indices of the esters depend mainly on the number of trimethylsilylgroups in the molecule and exhibit only small effects of the constitution of the silicic acid framework. The 29Si-n.m.r. spectra of 9 silicic acid TMS-esters of different constitutions are recorded and the assignment of the signals to the individual building units of the esters are discussed. On the basis of these results the constitutions of hexamer silicic acid-TMS-esters is investigated. Two isomers of the bicyclo-hexasilicic acid ester [(CH3)3Si]10 [Si6O17] could be identified.
    Notes: Kieselsäuretrimethylsilylester unterschiedlicher Konstitution werden mit Hilfe der Gaschromatographie hinsichtlich ihres Retentionsindex und der Retentionstemperatur charakterisiert. Es wird gezeigt, daß die Retentionsdaten der Ester im wesentlichen von der Anzahl der Trimethylsilylgruppen im Molekül abhängen und nur wenig von der Konstitution des Kieselsäuregerüstes beeinflußt werden. Die 29Si-NMR-Spektren von neun Kieselsäure-TMS-Estern unterschiedlicher Konstitution wurden aufgenommen und die Zuordnung der Signale zu den einzelnen Baugruppen der Ester diskutiert. Auf der Grundlage dieser Ergebnisse wurden Konstitutionsuntersuchungen an hexameren Kieselsäure-TMS-Estern durchgeführt, die zur Identifizierung von zwei Isomeren des Bicyclohexakieselsäureesters [(CH3)3Si]10[Si6O17] führten.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19764240205
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  • 7
    Electronic Resource
    Electronic Resource
    Darstellung und spektroskopische Untersuchungen von hoch-verzweigten funktionellen SiloxanenProfessor Wolfgang Wieker zum 60. Geburtstage am 19. April 1987 gewidmet (1987)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 547 (1987), S. 100-108 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Spectroscopic Investigations of Highly Branched Functional SiloxanesThe preparation of the siloxanes [(Me3SiO)3SiO]n(Me3SiO)3-nSiX and (Me3SiO)3Si[OSi(OSiMe3)2]2X (n = 1-3, X = H, Cl, OC2H5, OH) is described.The hydride-siloxanes and the siloxanoles have been investigated by i.r. and 29Si-n.m.r. spectroscopy. The frequencies of the Si—H stretching vibration, the 29Si—1H coupling constants and the 29Si-chemical shifts of the Si(H) signal for the hydride-siloxanes as well as the frequencies of the (Si)O—H stretching vibration, the relative (Si)O—H acidity, and the 29Si-chemical shifts of the Si(OH) signal for the siloxanoles show a dependence on the number of the (Me3SiO)3SiO groups. The spectroscopic data are discussed with respect to the silicate environment of the Si(H) and Si(OH) atom, respectively.In the siloxanoles intramolecular hydrogen bondings were observed.
    Notes: Die Darstellung der Siloxane [(Me3SiO)3SiO]n(Me3SiO)3-nSiX und (Me3SiO)3Si[OSi(OSiMe3)2]2X (n = 1-3, X = H, Cl, OC2H5, OH) wird beschrieben.Die Hydridsiloxane und Siloxanole wurden IR- und 29Si-NMR-spektroskopisch untersucht. Sowohl die Bandenlagen der Si—H-Valenzschwingung, die 29Si—1H-Kopplungskonstanten und die 29Si-chemischen Verschiebungen des Si(H)-Signals der Hydridsiloxane als auch die Bandenlagen der (Si)O—H-Valenzschwingung, die relative (Si)O—H-Acidität und die 29Si-chemischen Verschiebungen des Si(OH)-Signals der Siloxanole zeigen eine Abhängigkeit von der Anzahl der (Me3SiO)3SiO-Gruppen. Die spektroskopischen Daten werden unter dem Aspekt der silicatischen Umgebung des Si(H)-bzw. Si(OH)-Atoms diskutiert.In den Siloxanolen wurden intramolekulare Wasserstoffbrückenbindungen beobachtet.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19875470411
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  • 8
    Electronic Resource
    Electronic Resource
    Über die Reaktion der käfigartigen vinylsilylierten Doppelvierringkieselsäure [(CH2=CH)(CH3)2Si]8Si8O20 mit HSi≡-haltigen Verbindungen und die Herstellung eines neuen Polymers (1990)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 583 (1990), S. 133-144 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Reaction of the Cage-like Vinylsilylated Double Four-ring Silicic Acid [(CH2=CH)(CH3)2Si]8Si8O20 with HSi≡ Containing Compounds and the Preparation of a New PolymerBy means of 29Si, 13C and 1H NMR it has been shown that the compounds ((CH3)3SiO)2CH3SiH and (C2H5)3SiH react completely with the eight vinyl groups of the cage-like silicic acid derivate [(CH2=CH)(CH3)2Si]8Si8O20 (Q8M8V). The reactions do not follow the Markovnikov rule and give derivatives of the formula [((CH3)3SiO)2CH3Si(CH2)2Si(CH3)2]8Si8O20 and [(C2H5)3Si(CH2)2Si(CH3)2]8Si8O20, respectively. The reaction of Q8M8V with the likewise cage-like silicic acid derivative Q8M8H in the molar ratio of 1:1 results in an insoluble polymer consisting of cross-linked double fourring silicic acid units. Due to the sterical hindrance the polymer includes parts of unreacted vinyl and H groups. Molar ratios of 〉 1 result in increasing amounts of a soluble polymer.
    Notes: Mit Hilfe der 29Si-, 13C- und 1H-NMR wird gezeigt, daß mit ((CH3)3SiO)2CH3SiH und (C2H5)3SiH eine vollständige Addition der acht Vinylgruppen des käfigartig aufgebauten Kieselsäurederivats [(CH2=CH)(CH3)2Si]8Si8O20 (Q8M8V) erfolgt. Die Addition verläuft entgegen der Markovnikov-Regel unter Bildung der Kieselsäurederivate [((CH3)3SiO)2CH3Si(CH2)2Si(CH3)2]8Si8O20 bzw. [(C2H5)3Si(CH2)2Si(CH3)2]8Si8O20. Die Reaktion des Q8M8V mit dem ebenfalls käfigartig aufgebauten Kieselsäurederivat Q8M8H führt bei einem Molverhältnis (MV) von 1:1 zu einem unlöslichen Polymer, das aus vernetzten Doppelvierringkieselsäureeinheiten aufgebaut ist und aus sterischen Gründen Anteile unumgesetzter Vinyl- und H-Gruppen enthält. Bei einem MV 〉 1 bilden sich zunehmend in organischen Lösungsmitteln lösliche Polymere.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19905830116
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  • 9
    Electronic Resource
    Electronic Resource
    Spektroskopische Untersuchungen zu Substituenteneffekten in Silylmethylsilanen (1990)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 583 (1990), S. 195-204 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Spectroscopic Investigations on Substituent Effects in SilylmethylsilanesThe silanes Me3-n(Me3SiCH2)nSiH (n = 1-3), (RMe2SiCH2)3SiH (R = n-Bu, n-Pr, Et, PhCH2, Ph) and Me3ElCH2SiMe2H (El = Ge, Sn) were prepared. The frequencies of the Si—H stretching vibration, the 29Si—1H coupling constants and the 29Si n.m.r. chemical shifts were measured. The ṽ(SiH) and J(29Si—1H) values in the silanes Me3-n(Me3SiCH2)nSiH depend on the number of trimethylsilymethyl groups. There is hardly an influence of the substituents R on these values in the silanes (RMe2SiCH2)3SiH. The frequencies of the Si—H stretching vibrations in the silanes Me3ElCH2SiMe2H (El = Si, Ge, Sn) show the order Si=Ge 〉 Sn. The 29Si n.m.r. chemical shifts of the Si(H) signals are approximately equal in the silanes Me3-n(Me3SiCH2)nSiH and (RMe2SiCH2)3SiH.
    Notes: Die Silane Me3-n(Me3SiCH2)nSiH (n = 1-3), (RMe2SiCH2)3SiH (R = n-Bu, n-Pr, Et, PhCH2, Ph) und Me3ElCH2SiMe2H (El = Ge, Sn) wurden dargestellt. Die Bandenlagen der Si—H-Valenzschwingungen, die 29Si—1H-Kopplungskonstanten und die 29Si-NMR-chemischen Verschiebungen wurden gemessen. Die ṽ(SiH)- und J(29Si—1H)-Werte der Silane Me3-n(Me3SiCH2)nSiH sind von der Anzahl der Trimethylsilylmethylgruppen abhängig. Die Substituenten R haben auf diese Werte in den Silanen (RMe2SiCH2)3SiH kaum einen Einfluß. Für die Frequenzen der Si—H-Valenzschwingungen in den Silanen Me3ElCH2SiMe2H (El = Si, Ge, Sn) ergibt sich die Abstufung Si=Ge 〉 Sn. Die 29Si-NMR-chemischen Verschiebungen des Si(H)-Signals der Silane Me3-n(Me3SiCH2)nSiH und (RMe2SiCH2)3 SiH sind annähernd gleich.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19905830124
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  • 10
    Electronic Resource
    Electronic Resource
    NMR-spektroskopische Untersuchung der Reaktion von 3-Aminopropyltriethoxysilan mit Kieselsäurelösungen (1990)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 588 (1990), S. 199-207 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: N.M.R. Spectroscopic Investigation on the Reaction of 3-Aminopropyltriethoxysilane with Silicic Acid Solutions29Si and 14N NMR spectroscopic investigations on the reaction of aminopropyltriethoxysilane (APTS) and Silicic acid (KS) in an acidic water solution (molar ratio APTS/KS = 1:1; CSiO2 = 0.45 M; pH = 2.3) showed a strongly retarded condensation reaction of silicic acids. As motive cocondensation reactions of APTS with KS and the existence of —NH3+…-OSi≡ bonds are discussed. Due to the domination of —NH3+ against —NH2 groups up to pH 10.1 there exist also in neutral and alkaline APTS/KS solutions silicic acids and silicate anions, resp., stable against condensation. By concentration of APTS/KS solutions water soluble solids rich in silicic acid can be prepared.
    Notes: 29Si- und 14N-NMR-Untersuchungen der Reaktion von Aminopropyltriethoxysilan (APTS) und Kieselsäure (KS) in sauren wäßrigen Lösungen (Molverhältnis APTS/KS = 1:1, CSiO2 = 0,45 M; pH = 2,3) zeigen, daß durch APTS die Kondensationsreaktionen der KS stark verlangsamt werden. Als Ursachen werden partielle Kokondensationsreaktionen des APTS mit der KS und das Vorliegen von —NH3+…-OSi≡ Bindungen diskutiert. Durch die Dominanz von —NH3+ gegenüber —NH2-Gruppen bis pH 10,1 liegen auch in neutralen und schwach basischen APTS/KS-Lösungen kondensationsbeständige Kieselsäuren bzw. Silicatanionen vor. Durch Konzentrieren der APTS/KS-Lösungen sind kieselsäurereiche, wasserlösliche Feststoffe darstellbar.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19905880123
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