CLOPPA RPA-AM1 ANALYSIS OF THE ANISOTROPY OF NMR (1)J(XY) COUPLING TENSORS IN ME(3)XY COMPOUNDS (X=C-13, SI-29, SN-119, PB-207, Y=F-19, CL-35)

In this work, the CLOPPA approach is extended to allow the bond-contri bution analysis of the anisotropic part, Delta J, of the indirect nucl ear spin-spin coupling tensor, J. As an example this method is applied to study the role played by the X-Y bond, its antibonding orbital, an d the Y lone pairs in determining the Fermi contact-spin dipolar cross contribution to Delta(1)J(XY) in compounds of type Me(3)X-Y (X = C, S i, Sn, Pb; Y = F, Cl). That contribution is found to be the main one, except for X = Pb, in this series of compounds. Calculations are carri ed out using semiempirical AM1 ground-state wave functions. (C) 1997 J ohn Wiley & Sons, Inc.