The co-ordinates and an isotropic atomic displacement parameter were refined for all atoms, including the hydrogens. Ellipsoids showing isotropic refinement of atomic displacement parameters are shown in Figure .2. Intensity statistics (specifically, Rsigma i values for different resolution bins) were used to assess the quality of the data and therefore an appropriate cut-off resolution for the final refinement. Based on this, the refinement resolution was truncated to 0.90 Å, resulting in an R-factor of 10.93%. In the final cycle of refinement, there was no need for any geometric or atomic displacement restraints on the model. Table .2 summarises all relevant crystallographic information.