𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Study of solvent effects on the nitrogen NMR shieldings of some indolizines

✍ Scribed by M. Witanowski; W. Sicińska; Z. Grabowski; G. A. Webb

Publisher
John Wiley and Sons
Year
1990
Tongue
English
Weight
528 KB
Volume
28
Category
Article
ISSN
0749-1581

No coin nor oath required. For personal study only.

✦ Synopsis

Abstract

Solvent effects on the nitrogen NMR shieldings of indolizine and three azaindolizines are presented for a range of thirteen solvents. The results are discussed in terms of hydrogen‐bonding an solvent polarity effects. ‘Pyridine‐type’ nitrogen atoms show a much larger range of solvent effects than do ‘pyrrole‐type’ nitrogens; solvent to solute hydrogen bonding is the dominant contribution to the changes in shielding for the ‘pyridine‐type’ nitrogen atoms as the solvent is varied. Solvent polarity effects are important for both types of nitrogen atom in azaindolizines and can be attributed to a solvent‐induced electronic charge separation between the nitrogen atoms concerned.

Quantum chemical calculations involving the solvaton model are used to provide supporting evidence for the importance of solvent polarity effects on nitrogen shieldings in azaindolizines.

📜 SIMILAR VOLUMES

Solvent-Induced Effects on the Nitrogen
Solvent-Induced Effects on the Nitrogen NMR Shieldings of Some Nitrosobenzene Systems
✍ M. Witanowski; Z. Biedrzycka; W. Sicinska; G. A. Webb 📂 Article 📅 1997 🏛 John Wiley and Sons 🌐 English ⚖ 260 KB 👁 2 views

High-precision 14N NMR measurements of solvent-induced shielding variations are reported for some nitrosobenzene systems. These variations are shown to result from a combination of three major factors, solvent to solute hydrogen bonding where the solute nitrogen lone pair electrons are involved, sol

Study of hydrogen bonding and solvent po
Study of hydrogen bonding and solvent polarity effects on the nitrogen NMR shieldings of N,N-dimethylacetamidine
✍ Michal Witanowski; Wanda Sicinska; Zenobia Biedrzycka; Graham A. Webb 📂 Article 📅 2000 🏛 John Wiley and Sons 🌐 English ⚖ 148 KB 👁 2 views

Solvent effects on the nitrogen shieldings of N,N-dimethylacetamidine (1) were found to be extremely large for the imino group (about 120 ppm) and for the amino moiety (about 50 ppm). A detailed analysis of the solvent-induced variations revealed contributions from three large interactions. These ar

Effects of solute–solvent interactions o
Effects of solute–solvent interactions on the nitrogen nuclear shieldings of some alkyl cyanides
✍ M. Witanowski; W. Sicinska; G. A. Webb 📂 Article 📅 1989 🏛 John Wiley and Sons 🌐 English ⚖ 520 KB

It was found that the range of solvent effects on the nitrogen NMR shielding of the cyano group appears to he almost independent of the nature of the attached alkyl group and to be in excess of 20 ppm. Effects due to both the polarity of the medium and hydrogen bonding are observed to contribute alm