The Largest <sup>15</sup>N–<sup>15</sup>N Coupling Constant Across an NHN Hydrogen Bond

Pietrzak, Mariusz; Try, Andrew C.; Andrioletti, Bruno; Sessler, Jonathan L.; Anzenbacher, Pavel; Limbach, Hans−Heinrich

doi:10.1002/anie.200704411

Cited by 32 publications

(31 citation statements)

References 37 publications

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“…It is the point of importance that the angle ζ between the H· · ·N hydrogen bond and N-H covalent bond (see Scheme 2) changes on going from the simple N-H· · ·N hydrogen bond in 1-and 2-Z,E to the bifurcated N(O)· · ·H· · ·N hydrogen bond in 1-and 2-Z,Z, this angle being larger by [10][11][12][13][14][15][16][17][18][19][20] • in the former compounds.…”

Section: Resultsmentioning

confidence: 99%

“…[11] Largest value of 2h J(N,N) = 16.5 Hz was determined in the deprotonated anion of 2,3-dipyrrolyl-2-ylquinoxalines. [12] In addition, the 1h J(N,H) value of ca 2 Hz through the intramolecular O-H· · ·N hydrogen bond was measured in some biomolecules. [13] Many articles were devoted to the calculations of the transhydrogen bond coupling constants at the density functional theory (DFT) and ab initio levels.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical study of bifurcated hydrogen bonding effects on the ¹J(N,H), ^1hJ(N,H), ^2hJ(N,N) couplings and ¹H, ¹⁵N shieldings in model pyrroles

Afonin

Vashchenko

2010

Magnetic Reson in Chemistry

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According to the density functional theory calculations, the X...H...N (X=N, O) intramolecular bifurcated (three-centered) hydrogen bond with one hydrogen donor and two hydrogen acceptors causes a significant decrease of the (1h)J(N,H) and (2h)J(N,N) coupling constants across the N-H...N hydrogen bond and an increase of the (1)J(N,H) coupling constant across the N-H covalent bond in the 2,5-disubstituted pyrroles. This occurs due to a weakening of the N-H...N hydrogen bridge resulting in a lengthening of the N...H distance and a decrease of the hydrogen bond angle at the bifurcated hydrogen bond formation. The gauge-independent atomic orbital calculations of the shielding constants suggest that a weakening of the N-H...N hydrogen bridge in case of the three-centered hydrogen bond yields a shielding of the bridge proton and deshielding of the acceptor nitrogen atom. The atoms-in-molecules analysis shows that an attenuation of the (1h)J(N,H) and (2h)J(N,N) couplings in the compounds with bifurcated hydrogen bond is connected with a decrease of the electron density rho(H...N) at the hydrogen bond critical point and Laplacian of this electron density nabla(2)rho(H...N). The natural bond orbital analysis suggests that the additional N-H...X interaction partly inhibits the charge transfer from the nitrogen lone pair to the sigma*(N-H) antibonding orbital across hydrogen bond weakening of the (1h)J(N,H) and (2h)J(N,N) trans-hydrogen bond couplings through Fermi-contact mechanism. An increase of the nitrogen s-character percentage of the N-H bond in consequence of the bifurcated hydrogen bonding leads to an increase of the (1)J(N,H) coupling constant across the N-H covalent bond and deshielding of the hydrogen donor nitrogen atom.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Theoretical study of bifurcated hydrogen bonding effects on the ¹J(N,H), ^1hJ(N,H), ^2hJ(N,N) couplings and ¹H, ¹⁵N shieldings in model pyrroles

Afonin

Vashchenko

2010

Magnetic Reson in Chemistry

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“…[4]). This is due to the importance of nitrogen in biomolecules and in heterocycles and also to the fact that it is much easier to label a molecule with 15 N than with 13 C.…”

Section: Introductionmentioning

confidence: 97%

“…[1,2] There exist many situations for an A-H· · ·B hydrogen bond (HB) in what concerns the nature of A and B. In most cases, A and B are spin 1/2 nuclei such as 13 C, 15 N, 19 F and 31 P but the most studied, both in biomolecules at room temperature and in small organic molecules at very low temperatures, is the case where A = B = 15 N (for a recent theoretical example concerning proton sponges, see Ref. [3] and for another concerning experimental studies of intramolecular HBs, see Ref.…”

Section: Introductionmentioning

confidence: 99%

A theoretical structural analysis of the factors that affect ¹J_NH, ^1hJ_NH and ^2hJ_NN in N–H···N hydrogen‐bonded complexes

Alkorta¹,

Blanco²,

Elguero³

2008

Magnetic Reson in Chemistry

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Calculations of 1 JNH, 1h JNH and 2h JNN spin–spin coupling constants of 27 complexes presenting N–H·N hydrogen bonds have allowed to analyze these through hydrogen‐bond coupling as a function of the hybridization of both nitrogen atoms and the charge (+1, 0, − 1) of the complex. The main conclusions are that the hybridization of N atom of the hydrogen bond donor is much more important than that of the hydrogen bond acceptor. Positive and negative charges (cationic and anionic complexes) exert opposite effects while the effect of the transition states ‘proton‐in‐the‐middle’ is considerable. Copyright © 2008 John Wiley & Sons, Ltd.

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“…[6][7][8] Many experimental studies have considered the bonding situation in proton sponge cations. NMR [8][9][10][11] and IR spectroscopy, [12][13][14][15][16][17] and X-ray diffraction [12][13][14][15] are typical methods used for the examination of such systems. Nevertheless, it is very difficult to draw conclusions regarding the hydrogen dynamic behavior from purely experimental data.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Motion in Proton Sponge Cations: A Theoretical Study

Horbatenko

Vyboishchikov

2011

ChemPhysChem

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This work presents a study of intramolecular NHN hydrogen bonds in cations of the following proton sponges: 2,7-bis(trimethylsilyl)-1,8-bis(dimethylamino)naphthalene (1), 1,6-diazabicyclo[4.4.4.]tetradecane (2), 1,9-bis(dimethylamino)dibenzoselenophene (3), 1,9-bis(dimethylamino)dibenzothiophene (4), 4,5-bis(dimethylamino)fluorene (5), quino[7,8-h]quinoline (6) 1,2-bis(dimethylamino)benzene (7), and 1,12-bis(dimethylamino)benzo[c]phenantrene (8). Three different patterns were found for proton motion: systems with a single-well potential (cations 1-2), systems with a double-well potential and low proton transfer barrier, ΔEe (cations 3-5), and those with a double-well potential and a high barrier (cations 6-8). Tests of several density functionals indicate that the PBEPBE functional reproduces the potential-energy surface (PES) obtained at the MP2 level well, whereas the B3LYP, MPWB1K, and MPW1B95 functionals overestimate the barrier. Three-dimensional PESs were constructed and the vibrational Schrödinger equation was solved for selected cases of cation 1 (with a single-well potential), cation 4 (with a ΔEe value of 0.1 kcal mol(-1) at the MP2 level), and cations 6 (ΔEe = 2.4 kcal mol(-1)) and 7 (ΔEe=3.4 kcal mol(-1)). The PES is highly anharmonic in all of these cases. The analysis of the three-dimensional ground-state vibrational wave function shows that the proton is delocalized in cations 1 and 4, but is rather localized around the energy minima for cation 7. Cation 6 is an intermediate case, with two weakly pronounced maxima and substantial tunneling. This allows for classification of proton sponge cations into those with localized and those with delocalized proton behavior, with the borderline between them at ΔEe values of about 1.5 kcal mol(-1). The excited vibrational states of proton sponge cations with a low barrier can be described within the framework of a simple particle-in-a-box model. Each cation can be assigned an effective box width.

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The Largest ¹⁵N–¹⁵N Coupling Constant Across an NHN Hydrogen Bond

Cited by 32 publications

References 37 publications

Theoretical study of bifurcated hydrogen bonding effects on the ¹J(N,H), ^1hJ(N,H), ^2hJ(N,N) couplings and ¹H, ¹⁵N shieldings in model pyrroles

Theoretical study of bifurcated hydrogen bonding effects on the ¹J(N,H), ^1hJ(N,H), ^2hJ(N,N) couplings and ¹H, ¹⁵N shieldings in model pyrroles

A theoretical structural analysis of the factors that affect ¹J_NH, ^1hJ_NH and ^2hJ_NN in N–H···N hydrogen‐bonded complexes

Hydrogen Motion in Proton Sponge Cations: A Theoretical Study

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The Largest 15N–15N Coupling Constant Across an NHN Hydrogen Bond

Cited by 32 publications

References 37 publications

Theoretical study of bifurcated hydrogen bonding effects on the 1J(N,H), 1hJ(N,H), 2hJ(N,N) couplings and 1H, 15N shieldings in model pyrroles

Theoretical study of bifurcated hydrogen bonding effects on the 1J(N,H), 1hJ(N,H), 2hJ(N,N) couplings and 1H, 15N shieldings in model pyrroles

A theoretical structural analysis of the factors that affect 1JNH, 1hJNH and 2hJNN in N–H···N hydrogen‐bonded complexes

Hydrogen Motion in Proton Sponge Cations: A Theoretical Study

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The Largest ¹⁵N–¹⁵N Coupling Constant Across an NHN Hydrogen Bond

Theoretical study of bifurcated hydrogen bonding effects on the ¹J(N,H), ^1hJ(N,H), ^2hJ(N,N) couplings and ¹H, ¹⁵N shieldings in model pyrroles

Theoretical study of bifurcated hydrogen bonding effects on the ¹J(N,H), ^1hJ(N,H), ^2hJ(N,N) couplings and ¹H, ¹⁵N shieldings in model pyrroles

A theoretical structural analysis of the factors that affect ¹J_NH, ^1hJ_NH and ^2hJ_NN in N–H···N hydrogen‐bonded complexes