𝔖 Bobbio Scriptorium
✦   LIBER   ✦

DFT studies of the conformational/structural dependencies of geminal 1H,1H scalar coupling 2J(H,H′) in substituted methanes

✍ Scribed by Michael Barfield

Publisher
John Wiley and Sons
Year
2007
Tongue
English
Weight
356 KB
Volume
45
Category
Article
ISSN
0749-1581

No coin nor oath required. For personal study only.

✦ Synopsis

A study is presented of the structural dependencies for scalar, interproton J-coupling across two bonds in a series of substituted methanes. The coupled perturbed, density functional theory method with a B3PW91 functional and aug-cc-pVTZ-J basis sets is used to examine coupling between geminal protons 2 J(H,H ) in methane and a series of substituted compounds CH 3 X (X = CH 3 , CH 2 CH 3 , CH CH 2 , CH O, and NH 2 ) as functions of the dihedral angle j measured about the C1-X2 bonds. All four contributions are obtained but all conformational effects are dominated by the Fermi contact term. Simple linear combination of atomic orbitals (LCAO)-molecular orbital (MO) sum-over-states methods are used to examine the relationships of the coupling constants with dihedral angles as well as internal H-C-H and H-C1-X2 angles. This study explores some novel aspects of geminal H-H coupling including an analysis of the asymmetry in the conformational dependencies arising from non-next-nearest neighbor interactions. For each of the substituted methanes, explicit trigonometric/exponential expressions are given and these accurately reproduce the 2 J(H,H ) structural dependencies with standard deviations usually less than 0.03 Hz. The molecular structures for representative bicyclic molecules were fully optimized, and DFT results for 2 J(H,H ) reproduce all the trends in the experimental data. A discussion is given on the applicability of the equations for H-H coupling in the substituted methanes to coupling in the bicyclic molecules. Copyright

📜 SIMILAR VOLUMES

DFT/FPT studies of the structural depend
DFT/FPT studies of the structural dependencies of long-range 1H,1H coupling over four bonds 4J(H,H′) in propanic and allylic systems
✍ Michael Barfield 📂 Article 📅 2003 🏛 John Wiley and Sons 🌐 English ⚖ 424 KB

## Abstract A study is presented of the structural dependencies for scalar __J__‐coupling across four bonds in propanic and allylic systems. Density functional theory (DFT) and finite perturbation theory (FPT) were used to obtain the Fermi contact (FC) contributions to ^1^H,^1^H coupling. Interprot

Angular dependence of geminal spin–spin
Angular dependence of geminal spin–spin coupling constants in a prototype CH2 group. J(H,H) versus interbond angle in methane
✍ Jan Geertsen; Jens Oddershede; William T. Raynes 📂 Article 📅 1993 🏛 John Wiley and Sons 🌐 English ⚖ 383 KB

## Abstract Correlated __ab initio__ calculations of the dependences of the proton–proton spin–spin coupling constant __J__(H~1~, __H__~2~) in methane with the variation of the H~1~CH~2~ interbond angle are reported. The other coupling constants, including __J__(C, H), were simultaneously calcula

1H-detected studies of geminal 29Si13C c
1H-detected studies of geminal 29Si13C couplings: Dependence of coupling sign and magnitude on molecular structure
✍ Ēriks Kupč; Bernd Wrackmeyer 📂 Article 📅 1992 🏛 John Wiley and Sons 🌐 English ⚖ 343 KB

## Abstract The magnitude and signs of geminal ^29^SiZ^13^C coupling constants were determined for nine derivatives of representative organosilicon compounds [Z = C(sp^2^, sp^3^), N, O, (two‐ and three‐coordinate), Si, S] from ^1^H‐detected two‐dimensional (2D) Ψ‐BIRD‐HSQC and Ψ‐BIRD‐HMQC pseudo‐

Structural trends of 77Se1H spin–spin co
Structural trends of 77Se1H spin–spin coupling constants and conformational behavior of 2-substituted selenophenes
✍ Yury Yu. Rusakov; Leonid B. Krivdin; Stephan P. A. Sauer; Ekaterina P. Levanova; 📂 Article 📅 2009 🏛 John Wiley and Sons 🌐 English ⚖ 218 KB

## Abstract Experimental measurements and second‐order polarization propagator approach (SOPPA) calculations of ^77^Se^1^H spin–spin coupling constants together with theoretical energy‐based conformational analysis in the series of 2‐substituted selenophenes have been carried out. A new basis set

Density functional theory studies of tra
Density functional theory studies of transannular 1H1H J-coupling in half-cage alcohols and rigid 1,3- and 1,4-diols: conformational dependencies and implications for intramolecular hydrogen bond detection in carbohydrates
✍ Michael Barfield; Jon M. Bergset; Daniel J. O'Leary 📂 Article 📅 2001 🏛 John Wiley and Sons 🌐 English ⚖ 426 KB

Density functional theory (DFT) methods were used to investigate the conformational dependence of transannular H-H coupling constants in half-cage alcohols and cage diols. Finite perturbation theory (FPT) was used to obtain the Fermi contact (FC) contributions to scalar coupling constants in three h