Figure 1 A fragment of the molecular layer showing a dimeric moiety with atom labelling scheme and 50% probability displacement ellipsoids. Symmetry code: i -x + [{1\over 2}], y - [{1\over 2}], -z + [{3\over 2}]; ii -x, -y,-z + 1; iii x - [{1\over 2}], -y + [{1\over 2}], z + [{1\over 2}].  [article HTML]