Implementation of the IPPP-CLOPPA-INDO/S method for the study of indirect nuclear spin coupling constants and its application to molecules containingtin nuclei

The inner projection of the polarization propagator, using contributions fr om localized orbitals, IPPP-CLOPPA, and using the intermediate neglect of t he differential overlap model parameterized for spectroscopy, INDO/S, was i mplemented and used to calculate indirect nuclear spin coupling constants. The resulting model was tested on a group of small- and medium-size model c ompounds by comparing its performance with that of other semi-empirical met hods and experiments where available. It is shown that in general the INDO/ S approximation with the use of S-N(2)(O) and (r(N)(-3)) atomic parameters taken from the INDO and AM1 approaches is the most suitable scheme to descr ibe coupling constants. The introduction of atomic parameters for S-N(2)(0) and [r(N)(-3)] in the case of heavy nuclei like Sn, is a critical step. Th e correction of the bonding beta parameter for this nucleus was also necess ary within the INDO/S approximation to improve the accuracy and to better a ccount for indirect relativistic effects. The application of this parameter ization was accomplished in a series of tetrastannacyclohexanes and differe nt pathways for coupling transmission were analyzed. (C) 2000 Elsevier Scie nce S.A. All rights reserved.