Figure 1 The asymmetric unit of the title compound. Displacement ellipsoids are drawn at the 30% probability level. [Symmetry codes: (i) [{1\over 2}] + x, [{3\over 2}] - y, -[{1\over 2}] + z; (ii) [{3\over 2}] - x, -[{1\over 2}] + y, [{1\over 2}] - z; (iii) 2 - x, 1 - y, -z.]  [article HTML]