New Method to Study Spin-Spin Coupling Constants Involving Heavy Nuclei at the MNDO-RPA Level with Localized Orbitals

GUSTAVO A. AUCAR; RUBÉN H. CONTRERAS

JOURNAL OF MAGNETIC RESONANCE

ACADEMIC PRESS INC ELSEVIER SCIENCE

Lugar: Amsterdam; Año: 1991 vol. 93 p. 413 - 418

1090-7807

The calculation of spin-spin coupling constants has proven to be a very difficult task for molecular orbital theory. The state of the art of such calculations is discussed in detail in the ?Specialist Periodical Reports on Nuclear Magnetic Resonance? published annually by the Royal Society of Chemistry ( 1). Clear accounts of many problems involved in the theoretical analysis can also be found in both of Kowalewski?s reviews (2). At present two different lines of approach for such calculations can be distinguished. They use either very good quality ab initio wavefunctions or semiempirical methods to describe the ground state ( Ia). The obvious advantage of the former approach,w ith respectt o both accuracya nd rigorousnessa, s comparedw ith the second one can hardly be stressed enough. However, precise ab initio calculations are so demanding computationally that systematic calculations for medium-sized molecules have not yet been carried out despite the very large increase in computational facilities. In addition, those calculations have so far been performed only for molecules containing nonheavy nuclei.