Ab initio calculations of 31P NMR chemical shielding tensors in alkyl phosphorus compounds and comparison with experimental values

Ab initio calculations of P-31 nuclear shielding were performed as a function of the number of carbon atoms in twelve alkyl phosphorus compounds: PH3, PH2(CH3), PH(CH3)(2), P(CH3)(3), P(C2H5)(CH3)(2,) P(C2H5)(2)(CH3), P(C2H5)(2)(CHC2H6), P(C2H5)(CHC2H6)(2), P(CHC2H6)(3), P(CHC2H6)(2)(C(CH3)(3)), P(CHC2H6)(2)(C(CH3)(3))(2) and P(C(CH3)(3))(3). The calculation of the P-31 shielding tensors employed the GAUSSIAN 98 implementation of the gauge-including atomic orbital (GIAO) and continuous set of gauge transformations (CSGT) by using 6-311 ++G(2d,2p) basis set methods at both the Hartree-Fock (HF) and density functional levels of theories (DFT). A good linear correlation between the calculated chemical shielding at gas-phase and experimental shift values was obtained. (c) 2008 Elsevier B.V. All rights reserved.