A theoretical study of the acetate C-13 chemical shift tensor in cadmium acetate dihydrate

Theoretical calculations of the C-13 chemical shielding tensor were complet ed on different fragments of the crystal structure of cadmium acetate dihyd rate using the GIAO method. The calculations show the need for including in termolecular interactions in order to reproduce the experimental C-13 chemi cal shift tensors of charged species. When a large enough fragment of the c rystal is included in the calculation, the RMS difference between the exper imental and the theoretical chemical shift tensor is 7 ppm, in comparison t o differences of 64-20 ppm for calculations on isolated acetate anions and on cadmium acetate with and without waters of hydration. This RMS differenc e of 7 ppm is comparable to that obtained by calculations on neutral organi c molecules, completed using similar computational approaches but without t he inclusion of any intermolecular interactions. (C) 1999 Elsevier Science B.V. All rights reserved.