Abstract
This work deals with the calculation of nuclear spin-spin couplings, involving the nuclei in the second-row of the periodic table, in a wide variety of different organic and inorganic molecules by means of the INDO-SCPT approach. Two different basis sets, sp and spd, are used in order to evaluate and compare the relative importance of the three contributing terms to the couplings. The results obtained are analysed in an attempt to gain some understanding of the relation between the couplings and various features of molecular electronic structure. The theoretical background of nuclear spin-spin coupling interactions is introduced in Chapter 1. Chapter 2 is concerned with molecular orbital theory, different approximate MO methods and their application to SOS, FPT and SCPT approaches to spin-spin coupling. The extension of the INDO-SCPT-spd procedure to second-row atoms is described in the last section. All expressions for the couplings are presented in SI units. Chapter 3 presents the INDO-SCPT results for some couplings between 31P and nuclei other than protons, compared with available experimental data. The use of different MO basis sets and a discussion of the relevant factors which may effect the couplings of given coupled atoms are also included. In the last Chapter, the INDO-SCPT theory, with two different basis sets is employed for the calculation of couplings involving 29Si. The relative success and failure of the theory in reproducing signs and magnitudes of the observed couplings are discussed.