Theoretical and experimental H-1, C-13, N-15, and O-17 NMR chemical shiftsfor 5-halogenouracils

Theoretical and experimental H-1, C-13, N-15, and O-17 NMR chemical shifts for uracil and 5-halogenouracils were determined and analyzed. The theoreti cal NMR chemical shifts were calculated based on the HF and MP2 GIAO approa ch using the 3-21G**, MIDI!, polarized double zeta Hansen-Bouman, and the p olarized triple zeta Sadlej basis sets. The solvent effect was checked at t he HF/3-21G** level by surrounding the uracil molecule by seven water molec ules. For all the nuclei studied in the series of halogenouracils, linear c orrelation was tested between the chemical shift (both experimental and the oretical) and halogen electronegativity. All the carbon-proton and one-bond carbon-carbon spin-spin coupling constants were measured and used to assig n the carbon signals. (C) 2000 Elsevier Science B.V. All rights reserved.