Figure 1 A view of (I) with the unique atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. Minor component of disordered O1 atom as well as H atoms have been omitted. Unlabeled atoms are related to labeled atoms by the symmetry code (x, [{1\over 2}] - y, [{1\over 2}] - z)  [article HTML]