Intermediate exchange rates were modelled using EXPRESS. Input NMR parameters were taken from DFT/MD results. The relative chemical shift anisotropy (CSA) and EFG Euler angles were obtained using MagresView 99 where one angle set was arbitrarily defined as [0 0 0] with powder averaging providing iteration over all orientations. For the 'fast-intermediate' case, the MD averaged tensor was used as an input in MagresView. The rate constants used for each EXPRESS simulation were: MFU-4l -2.4 x 10 5 Hz, KHCO 3 (s) 1.4 x 10 14 Hz and K 2 CO 3 .1.5H 2 O(s) 1 x 10 4 Hz.