Density Functional Calculations of NMR Chemical Shifts with the Inclusion of Spin−Orbit Coupling in Tungsten and Lead Compounds

Both the Pauli spin−orbit Hamiltonian and the relativistic zero order regular approximation (ZORA) have been used in conjunction with the gauge including atomic orbital (GIAO) method based on density functional theory (DFT) to calculate 207Pb and 183W NMR chemical shifts. For the tungsten series WO3S2-, WO2S22-, WOS32-, WS42-, WO42-, W(CO)6, WCl6 and WF6, one finds the 183W chemical shift to be dominated by paramagnetic contributions, whereas the Fermi-contact contribution induced by spin−orbit coupling is of less importance. On the other hand, in the lead series Me3PbCl, Me3PbBr, Me3PbI, Me3PbOMe, Me3PbSMe, Me3PbSeMe, Me3PbNEt2, Me2PbCl2, and PbX4 (X = Cl, Br, I), the Fermi-contact term is the trend setting contribution. It is shown that ZORA in general provides chemical shift in better agreement with experiment than the simpler Pauli spin−orbit scheme.