Results 261 to 270 of about 1,481,196 (275)

B−N Distance Potential of CH₃CN−BF₃ Revisited:  Resolving the Experiment−Theory Structure Discrepancy and Modeling the Effects of Low-Dielectric Environments

The Journal of Physical Chemistry B, 2007
We have re-examined the B-N distance potential of CH3CN-BF3 using MP2, DFT, and high-accuracy multicoefficient methods (MCG3 and MC-QCISD). In addition, we have solved a 1-D Schrödinger equation for nuclear motion along the B-N stretching coordinate, thereby obtaining vibrational energy levels, wave functions, and vibrationally averaged B-N distances ...
James A, Phillips, Christopher J, Cramer
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Asymmetric Synthesis and Application of Homologous Pyrroline‐2‐alkylboronic Acids: Identification of the B–N Distance for Eliciting Bifunctional Catalysis of an Asymmetric Aldol Reaction.

Asian Journal of Organic Chemistry, 2013
AbstractHomoboroproline has been shown to be an efficient bifunctional catalyst for the aldol reaction of acetone with p‐nitrobenzaldehyde by using in situ Lewis acid tuning of the boronic acid esterification with a diol. Herein, asymmetric syntheses of homologues of this catalyst are developed to compare their catalytic capability and chemical ...
Batsanov, A. S., Georgiou, I., Girling, P. R., Pommier, L., Shen, H. C., Whiting, A.   +5 more
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Frequency Selective Heteronuclear Dipolar Recoupling in Rotating Solids:  Accurate¹³C−¹⁵N Distance Measurements in Uniformly¹³C,¹⁵N-labeled Peptides

Journal of the American Chemical Society, 2001
We describe a magic-angle spinning NMR experiment for selective (13)C-(15)N distance measurements in uniformly (13)C,(15)N-labeled solids, where multiple (13)C-(15)N and (13)C-(13)C interactions complicate the accurate measurement of structurally interesting, weak (13)C-(15)N dipolar couplings. The new experiment, termed FSR (frequency selective REDOR),
C P, Jaroniec, B A, Tounge, J, Herzfeld, R G, Griffin   +3 more
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Investigation of the double-well potential of the NH⋯N hydrogen bond of the guanine-cytosine base pair for different NN distances

Journal of Molecular Spectroscopy, 1968
Abstract The double-well potential of the NH⋯N hydrogen bond of the guanine-cytosine base pair was computed for different NN distances. For the calculations both the method of Rein and Harris and a corrected form of the semiempirical Lippincott-Schroeder method, which takes into account the change of the distribution of the π electrons caused by ...
D.K. Rai, J. Ladik
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ChemInform Abstract: Asymmetric Synthesis and Application of Homologous Pyrroline‐2‐alkylboronic Acids: Identification of the B—N Distance for Eliciting Bifunctional Catalysis of an Asymmetric Aldol Reaction.

ChemInform, 2014
AbstractThe influence of the chain length in homoboroproline homologues on their catalytic activity in aldol reactions is examined.
Andrei S. Batsanov, Irene Georgiou, P. Ricardo Girling, Laure Pommier, Hong C. Shen, Andrew Whiting   +5 more
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15N,15N spin-spin coupling constants across N?H?N and N?H+?N hydrogen bonds: can coupling constants provide reliable estimates of N?N distances in biomolecules?

Magnetic Resonance in Chemistry, 2001
Predictive quantum chemical methods based upon coupled cluster theory of spin–spin coupling constants offer a direct tool to explore a variety of questions concerning the relationship between coupling constants and intermolecular distances, molecular orientation, changes in hybridization and related issues.
Janet E. Del Bene, S. Ajith Perera, Rodney J. Bartlett   +2 more
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Scalar Coupling between the ¹⁵N Centres in Methylated 1,8‐Diaminonaphthalenes and 1,6‐Diazacyclodecane: To What Extent is ^2HJ_NN a Reliable Indicator of NN Distance?

Chemistry – A European Journal, 2003
AbstractThe scalar couplings between hydrogen bonded nitrogen centres (2HJNN) in the free‐base and protonated forms of the complete series of [15N2]‐N‐methylated 1,8‐diamino naphthalenes in [D7]DMF solution have been determined, either directly (15N{1H} NMR), or, indirectly (13C{1H} NMR and simulation of the X part of the ABX spectrum (X=13C, A,B=15N)).
Lloyd-Jones, GC, Harvey, JN, Hodgson, P, Murray, M, Woodward, RL   +4 more
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¹³C/¹⁵N distance determination by CPMAS NMR in uniformly ¹³C labeled molecules

Magnetic Resonance in Chemistry, 2005
AbstractThe REDOR and CPMAS techniques are applied for measuring 13C15N dipolar coupling constants in glycine. It is shown that the selective CP or SPECIFIC CP technique removes the coherent evolution of the spin system under homonuclear 13C13C J couplings.
Maggy, Hologne, Jésus, Raya, Jérôme, Hirschinger   +2 more
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On the Aggregation of n-distances

2022
Tomasa Calvo Sánchez, Pilar Fuster-Parra   +1 more
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On the Relationship Between Multidistances and n-Distances Revisited

2023
Tomasa Calvo Sánchez, Pilar Fuster-Parra   +1 more
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