Figure 1 Molecular structure showing the labelling scheme and the inter- and intra-molecular hydrogen bonding. Hydrogen atoms have been omitted for clarity. The non-hydrogen atoms are represented by displacement ellipsoids at the 20% probability level. Symmetry transformations used to generate equivalent atoms: (i) x + 1, y, z; (ii) -x, y - [{1\over 2}], -z; (v) -x, y - [{1\over 2}], -z + 1; (vi) x - 1, y, z + 1.  [article HTML]