1229smoothly from visual models to packing refinement to 'before and after' views, all within a few minutes. This would not only lead to quicker model evaluation, but would also help avoid the occasional problem of false minima that can arise when PCK5 is used blindly. The crystal and molecular structure of ~-hydroxy-l,l-dimethylpyrrolidinium bromide 0~-phenyl-2-thiopheneglycolate (e heteronium bromide) Cash 22NOaSBr, was determined by single-crystal X-ray diffraction techniques. The crystals were orthorhombic, Din= 1"5 g cm -a, space group Pna2~, Z=4, a= 18-596 (1), b= 8.049 (9), and c= 12.297 (8)/~. The structure was solved using 1671 observed independent reflections to yield a final R value of ?-044.