Indirect spin-spin coupling constants across noncovalent bonds

Jaźwiński, Jarosław

doi:10.1016/bs.arnmr.2021.05.002

Cited by 4 publications

(3 citation statements)

References 151 publications

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“…These quantities are positive and negative for N and O, respectively. Although there are indications in the literature [54] that these intermolecular coupling constants tend to correlate with bond strength for various sorts of noncovalent bonds, their magnitudes are only very broadly indicative of E int . For example, J(I••N) drops from 278 to 218 Hz when the base coupled with PhI is switched out from NH 3 to NMe 3 , despite the rise in interaction energy.…”

Section: Nmr Datamentioning

confidence: 99%

“…A number of works have considered very small Lewis acids such as dihalogens [45,46,[51][52][53]. NMR coupling constants have been computed for the specific pair of atoms involved directly in the bond [39,[54][55][56] but little attention has been paid to the more peripheral nuclei or to the coupling constants within the Lewis acid unit. In connection with larger systems, a certain amount of attention has been drawn toward halobenzenes [57][58][59][60][61][62] where the X atom is connected to a simple phenyl ring.…”

Section: Introductionmentioning

confidence: 99%

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Relation between Halogen Bond Strength and IR and NMR Spectroscopic Markers

Amonov,

Scheiner

2023

Molecules

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The relationship between the strength of a halogen bond (XB) and various IR and NMR spectroscopic quantities is assessed through DFT calculations. Three different Lewis acids place a Br or I atom on a phenyl ring; each is paired with a collection of N and O bases of varying electron donor power. The weakest of the XBs display a C–X bond contraction coupled with a blue shift in the associated frequency, whereas the reverse trends occur for the stronger bonds. The best correlations with the XB interaction energy are observed with the NMR shielding of the C atom directly bonded to X and the coupling constants involving the C–X bond and the C–H/F bond that lies ortho to the X substituent, but these correlations are not accurate enough for the quantitative assessment of energy. These correlations tend to improve as the Lewis acid becomes more potent, which makes for a wider range of XB strengths.

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Section: Nmr Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Relation between Halogen Bond Strength and IR and NMR Spectroscopic Markers

Amonov,

Scheiner

2023

Molecules

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“…There has been a substantial body of past research regarding the relevance of NMR coupling constants to halogen and related noncovalent bonding. [68,72,[74][75][76][77][78] In particular, the coupling constant between the two atoms directly involved in a XB seems to closely track with the strength of the bond. The pertinent coupling constant between I and N in the halogen bonded systems here is delineated by the red curve in Figure 3 (in units of 100 Hz so as to fit into the figure).…”

Section: Nmr Spectramentioning

confidence: 99%

Influence of Substituents in the Benzene Ring on the Halogen Bond of Iodobenzene with Ammonia

Scheiner

Hunter

2022

ChemPhysChem

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The effects on the CÀ I••N halogen bond between iodobenzene and NH 3 of placing various substituents on the phenyl ring are monitored by quantum calculations. Substituents R = N(CH 3 ) 2 , NH 2 , CH 3 , OCH 3 , COCH 3 , Cl, F, COH, CN, and NO 2 were each placed ortho, meta, and para to the I. The depth of the σ-hole on I is deepened as R becomes more electron-withdrawing which is reflected in a strengthening of the halogen bond, which varied between 3.3 and 5.5 kcal mol À 1 . In most cases, the ortho placement yields the largest perturbation, followed by meta and then para, but this trend is not universal. Parallel to these substituent effects is a progressive lengthening of the covalent CÀ I bond. Formation of the halogen bond reduces the NMR chemical shielding of all three nuclei directly involved in the CÀ I••N interaction. The deshielding of the electron donor N is most closely correlated with the strength of the bond, as is the coupling constant between I and N, so both have potential use as spectroscopic measures of halogen bond strength.

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