Electric field effects on the magnetic shielding of first and second row nuclei in some simple molecules

✍ Scribed by Martin Grayson; William T. Raynes

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 632 KB
• Volume: 214
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(93)85669-f

✦ Synopsis

The changes in the components of the nuclear shielding tensors which occur when a molecule is placed in a uniform electric field can be described by a Taylor series expansion. The coefficients in this expansion are sometimes referred to as "shielding polarizabilities". Following a study of electric field effects on '"C nuclear shielding in several organic molecules, values of the first-and second-order electric field coefficients have been obtained for the N, 0, F, Si, P, S and Cl nuclei in a variety of simple molecules and for Ne and Ar nuclei in the neutral atoms. As with the "C coefficients, the paramagnetic part of each coefficient is usually far greater -sometimes much more than one hundred times greater -than the diamagnetic part. For those. nuclei (N, 0, and F) studied in more than one molecule it is clear that the coeffkients are, as for carbon nuclei, strongly dependent on the nature of the bonding.