Figure 1.

The principal building units in the structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) x, −y + 1, z + ; (ii) −x + 1, y, −z + ; (iii) −x + 1, −y + 1, −z + 1; (iv) −x + 2, y, −z + ; (v) −x + 2, −y + 1, −z + 1; (vi) x + , −y + , z + ; (vii) −x + , −y + , −z + 1; (viii) x, −y + 1, z − ; (ix) −x + , y − , −z + ; (x) x + , −y + , z + ; (xi) −x + , −y + , −z + 1; (xii) −x + , y + , −z + ; (xiii) x + , y + , z + 1.]