학술논문
Molecular orbital studies in95Mo NMR shielding for[MoOnS(4 − n)]2− anions: Relations between chemical shift and molybdenum orbital electron populations
Document Type
Article
Author
Source
Polyhedron; July 1996, Vol. 15 Issue: 13 p2215-2221, 7p
Subject
Language
ISSN
02775387
Abstract
The95Mo NMR chemical shifts of[MoO4−nSn]2− (n = 0–4) have been analysed theoretically by semi-empirical, CNDO andab initio molecular orbital methods. The calculated values of molybdenum chemical shifts by correlating molybdenump- andd-orbital electron populations or the molybdenum total electron charge agreed well with the available experimental data on ¦gDGd¦ 2~ 20 ppm compared with the previously reported ¦gDGd¦ 2~ 140–300 ppm using similar calculation methods. The Mo chemical shift reflects the change in the valence4d- and5p-orbitals of molybdenum, but it is mainly determined by thep-orbital electron population by a factor beyond 10. This unequal contribution to the molybdenum shielding reflects the relevance ofp-orbitals in π-back-bonding for these compounds.