✍ Scribed by Janet E. Del Bene; S. Ajith Perera; Rodney J. Bartlett
No coin nor oath required. For personal study only.
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. Of particular interest are 2h J. 15 N, 15 N/ couplings across hydrogen bonds. In this work we present EOM-CCSD coupling constants [ 2h J. 15 N, 15 N/] for a series of cationic complexes stabilized by either traditional or protonshared N -H + -N hydrogen bonds, and relate these to 15 N, 15 N coupling constants in neutral complexes with N -H -N hydrogen bonds. The computed 15 N, 15 N coupling constants in these complexes vary smoothly with N -N distance, regardless of the charge or the particular binding at the N atoms. We propose that the curves which show this dependence have sufficient generality that they should be useful for determining N -N distances from experimentally measured coupling constants.
📜 SIMILAR VOLUMES
## Abstract An indirect method is employed for determining the ^15^N parameters at the natural abundance level in a series of simple acyclic and cyclic amides. The one bond coupling constant, ^1^__J__(^15^N^1^H), and the ^15^N chemical shift are measured as a function of the carbonyl substituent gr
The sign 'J(NN) of 2-chlor0-6-methyl-['~N,]pyrimidine has been determined by 'H-('H (selective), "N (selective)} and 13C-(1H (noise), I5N (selective)} triple resonance techniques. The sign was proved to be negative (-1.6 Hz); consequently, chlorine substitution at C-2 was found to make ' . I ( " ) m
Natural abundance 13C and 15N NMR studies were carried out on a series of N -methylated and N -tert -butylated tetrazoles. Longrange 13C,1H and 15N,1H NMR coupling constants together with 1J (15N,13C) allowed unequivocal assignments of 13C and 15N chemical shifts for isomeric 1,5-and 2,5-disubstitut
The two-bond "N,H coupling constant in 3,5dimethylpyridine was determined in 30 solvents and shown to vary between -11 and -3 Hz. An increasing ability of the solvent to form hydrogen bonds causes a steady decrease in I \*J("N,H) I , which is also observed with some selected pyridine derivatives wit