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1. |
The n.m.r. of paramagnetic complexes of vanadyl acetylacetonate with organic phosphites and hydroperoxides |
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Organic Magnetic Resonance,
Volume 9,
Issue 2,
1977,
Page 61-63
D. G. Pobedimskii,
Sh. A. Nasybullin,
P. A. Kirpichnikov,
R. B. Svitych,
O. P. Yablonskii,
A. L. Buchachenko,
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摘要:
AbstractThe vanadium IV ion in vanadyl acetylacetonate (VIV) forms labile paramagnetic complexes with organic phosphites in the first coordination sphere. The enthalpy of complex formation between VIVand triphenyl phosphite was 2.6 kcal mol−1. Complex formation enthalpies ΔHand the activation energiesEof ligand (hydroperoxide) escape from the metal ion sphere were determined from the temperature dependence of paramagnetic broadening of the n.m.r. lines of hydroperoxides in the presence of vanadyl acetylacetonate. At low temperatures the phosphite sharply weakens the bond between the metal ion and hydroperoxide in the second coordination sphere (ΔHdecreases fivefold). Taken in excess, phosphite displaces the hydroperoxide molecules from the coordination sphere of the VIVion and thus blocks it. The observed n.m.r. characteristics of the paramagnetic complexes explain, on the model level, the kinetic regularities of the reaction of hydroperoxides with phosphite catalysed by transient metal i
ISSN:0030-4921
DOI:10.1002/mrc.1270090202
出版商:John Wiley&Sons Limited
年代:1977
数据来源: WILEY
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2. |
Zur theoretischen Interpretation von NMR‐chemischen Verschiebungen tetrakoordinierter zentralatome. IV—CNDO/2‐Berechnungen von29Si‐NMR‐chemischen Verschiebungen. Der Einfluß der ΔE‐Näherung |
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Organic Magnetic Resonance,
Volume 9,
Issue 2,
1977,
Page 64-68
R. Wolff,
R. Radeglia,
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摘要:
AbstractAuf der Basis des CNDO/2‐Verfahrens werden paramagnetische Abschirmungskonstanten für das Zentralatom tetrasubstituierter Siliciumverbindungen Me4–nSiXn(X = F, OMe, NMe2, C1) mit und ohne ΔE‐Näherung berechnet und mit den experimentellen29Si‐NMR‐chemischen Verschiebungen verglichen. Die aus dem Vergleich der berechneten Werte erhaltenen ‘mittleren Anregungsenergien’ ΔEsind von der Ladung am Zentralatom abhängig und können für quantitative Betrachtungen nicht als konst
ISSN:0030-4921
DOI:10.1002/mrc.1270090203
出版商:John Wiley&Sons Limited
年代:1977
数据来源: WILEY
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3. |
Vicinal13CH coupling through olefinic double bonds |
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Organic Magnetic Resonance,
Volume 9,
Issue 2,
1977,
Page 69-70
Alan W. Douglas,
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摘要:
AbstractValues of long range13CH coupling through the double bond in a number of isopropenyl compounds are reported. There is evidence that substituent dependence of3J(CH) is not related linearly to that of HH couplings in vinyl compounds. The ratio of3J(CH) to3J(HH) in analogous pairs of compounds appears to increase with decreasing substituent polarity and increasing steric bul
ISSN:0030-4921
DOI:10.1002/mrc.1270090204
出版商:John Wiley&Sons Limited
年代:1977
数据来源: WILEY
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4. |
1H n.m.r. investigation on the site of hydration in the asymmetric diazanaphthalenes |
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Organic Magnetic Resonance,
Volume 9,
Issue 2,
1977,
Page 71-74
Peter van de Weijer,
Douwe van der Meer,
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摘要:
AbstractThe site of hydration for 1,6‐ and 1,7‐naphthyridine has been determined by specific line broadening in the1H n.m.r. spectra on the addition of water. The site of hydration appears to be the same as the site of protonation (β‐nitrogen atom). The site of hydration in quinazoline has been shown to be the α‐nitrogen atom. This strongly indicates that the site of protonation in this compound will also be at that
ISSN:0030-4921
DOI:10.1002/mrc.1270090205
出版商:John Wiley&Sons Limited
年代:1977
数据来源: WILEY
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5. |
Nuclear magnetic resonance studies: VII—13C and15N n.m.r. of diazo compounds |
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Organic Magnetic Resonance,
Volume 9,
Issue 2,
1977,
Page 75-79
Thomas A. Albright,
Walter J. Freeman,
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摘要:
AbstractThe13C and15N n.m.r. results for a series of diazo compounds are reported. It is found that the diazo carbon is shielded by an extraordinary amount compared with normal sp2hybridized carbons. The15N chemical shifts reveal that the terminal nitrogen is deshielded relative to the central one. This is contrary to that expected from charge effects but support is found for this phenomenon in other systems. One‐bond13C14N coupling in diazomethane is also reported for the first time. INDO MO calculations of the charges and finite perturbation calculations of13C14N and CH couplings are compared with the experimental
ISSN:0030-4921
DOI:10.1002/mrc.1270090206
出版商:John Wiley&Sons Limited
年代:1977
数据来源: WILEY
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6. |
Conformational analysis ofN,N‐diisopropylamides by combined use of n.m.r. lanthanide‐induced shifts and conformational energy calculations |
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Organic Magnetic Resonance,
Volume 9,
Issue 2,
1977,
Page 80-89
Laurine L. Graham,
Garret Vanderkooi,
Joseph A. Getz,
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摘要:
AbstractA new method of conformational analysis has been developed, in which energy minimization calculations are combined with lanthanide‐induced shift data. First, exhaustive energy calculations are carried out on the free molecules in order to determine the conformations of lowest energy. Then, the coordinates of all low energy conformations or pairs of conformations are used in the pseudocontact shift equation for lanthanide‐induced shifts in order to find which of the theoretically obtained conformation(s) gives the best agreement with experiment. The molecules complexed to the lanthanide shift reagent wereN,N‐diisopropylformamide (DIPF) andN,N‐diisopropylacetamide (DIPA). Two different lanthanide shift reagents were used, Eu(fod)3Fod is the anion of 1,1,1,2,2,3,3‐heptafluoro‐7,7‐dimethyl‐4,6‐octanedione‐d27.and Pr(fod)3, in order to check the validity of the method. Proton magnetic resonance spectra were taken at 6 °C in carbon tetrachloride solution. The principal conformation found was different for each amide. DIPF was found to exist as a mixture of I (39 mol%) and II (61 mol%) with Eu(fod)3, and a mixture of I (37%) and II(63%) with Pr(fod)3. DIPA was found to exist as a mixture of I (79%) and IV (21%) with Eu(fod)3and a mixture of I (87%) and IV (13%) with Pr(fod)3. For both molecules, the two conformations of lowest computed energy were also the pair which gave the best fit to the lanthanide shift reagent data. The location of the principal magnetic axis of the complex was found to lie between 0° and 14° from the lanthanide atom–oxygen atom bond axis. The technique of combining lanthanide shift reagent data with energy calculations shows great promise in
ISSN:0030-4921
DOI:10.1002/mrc.1270090207
出版商:John Wiley&Sons Limited
年代:1977
数据来源: WILEY
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7. |
NMR‐Untersuchungen an Dicyclopentadienderivaten: III—Stereochemische Zuordnung von überbrücktenendo‐Dicyclopentadienderivaten und deren Wagner‐Meerwein‐Umlagerungs‐produkten mit Hilfe der NMR‐Spektroskopie |
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Organic Magnetic Resonance,
Volume 9,
Issue 2,
1977,
Page 90-97
E. Kleinpeter,
H. Kühn,
M. Mühlstädt,
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摘要:
AbstractDie1H‐NMR‐Spektren einer Reihe substituierter Oxa‐ bzw. Azatetracycloundecane werden aufgezeigt und an ausgewählten Beispielen mit Hilfe von Spin‐Spin‐Entkopplung und Eu(fod)3—paramagnetischen Verschiebungsversuchen eingehend analysiert. Aus den mit angeführten13C‐NMR‐Spektren werden die einzelnen C‐Resonanzen unter Verwendung bekannter Substituenteneffekte und paramagnetischer Signal‐verschiebungen zugeordnet. Die paramagnetischen Verschiebungswerte ΔEu werden hinsichtlich ihrer Kontakt‐ und Pseudoko
ISSN:0030-4921
DOI:10.1002/mrc.1270090208
出版商:John Wiley&Sons Limited
年代:1977
数据来源: WILEY
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8. |
Therα‐structure of partially orientedm‐dichlorobenzene as determined from its proton magnetic resonance spectrum including the carbon–13 satellites |
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Organic Magnetic Resonance,
Volume 9,
Issue 2,
1977,
Page 98-100
P. Diehl,
H. Bösiger,
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摘要:
AbstractThe proton spectrum, including13C satellites at natural abundance, of partially orientedm‐dichlorobenzene was analysed. Carbon–carbon, carbon–hydrogen and hydrogen–hydrogen internuclear distance ratios, as well as bond angles were derived and corrected for harmonic vibrations (rα‐
ISSN:0030-4921
DOI:10.1002/mrc.1270090209
出版商:John Wiley&Sons Limited
年代:1977
数据来源: WILEY
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9. |
Determination of3J(31P31P) and13C31P coupling constants in 1,6‐diphosphatriptycene from carbon‐13 n.m.r. lone pairs effects on13C31P couplings |
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Organic Magnetic Resonance,
Volume 9,
Issue 2,
1977,
Page 101-104
S. Sørensen,
H. J. Jakobsen,
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摘要:
AbstractThe31P31P and13C31P coupling constants in 1,6‐diphosphatriptycene have been obtained from analysis of its proton decoupled13C n.m.r. spectra. More accurate data, however, resulted from simultaneous analysis of the proton decoupled13C spectra and31P(13C) satellite spectra. The13C31P couplings are strongly influenced by the proximity and orientation of the phosphorus lone pair electrons. The first31P31P coupling in an aromatic diphosphine is
ISSN:0030-4921
DOI:10.1002/mrc.1270090210
出版商:John Wiley&Sons Limited
年代:1977
数据来源: WILEY
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10. |
1H‐ und13C‐NMR‐untersuchungen an dibromoxabicyclo[n.2.1]alkanen |
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Organic Magnetic Resonance,
Volume 9,
Issue 2,
1977,
Page 105-107
E. Kleinpeter,
G. Haufe,
M. Mühlstädt,
J. Graefe,
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摘要:
AbstractDie1H‐NMR‐Spektren einer Reihe von Dibromoxabicyclo[n.2.1]alkanen werden zur Bestimmung der Konfiguration und Konformation herangezogen. Die13C‐NMR‐Spektren bestätigen die ermittelte Stereochemie. Mit zunehmender Ringgröße verlagern sich die13C‐chemischen Verschiebungen der heteroatomsubstituierten C‐Atome kontinuierlich nach
ISSN:0030-4921
DOI:10.1002/mrc.1270090211
出版商:John Wiley&Sons Limited
年代:1977
数据来源: WILEY
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