STRUCTURE OF TWINNED [Fe(heed3a)H₂O]. Gernot Zahn¹, Martin Boddin², Roland Meier², Peter Paufler¹, ¹Institut für Kristallographie und Festkörperphysik, Technische Universität Dresden, D 01062 Dresden, German,² Fachgruppe Chemie, Hochschule für Technik, Wirtschaft und Kultur Leipzig, D 04251 Leipzig, Germany

The X-ray single-crystal structure analysis revealed that iron is sevenfold coordinated in the yellow N-hydroxyethyl-ethylendiamine-triacetato iron(III) monohydrate (P 2₁/c, a = 7.375(2), b = 13.062(2), c = 13.856(6) Å,  = 101.91(1)deg.). Evidently yellow phase differs from brown phase in a different packing of complex and its enantiomorphous mirror image in the unit cell. The observed twinning can be described by two laws 1. rotation about [100] or 2. reflection through (001), which is in accordance with the centrosymmetrical space group and results in coinciding 0kl, separated 2kl, 3kl, 6kl, 7kl and overlapping 1kl, 4kl, 5kl reflections.

Fig. 1: Coordination polyhedron Fig. 2: Cell projection along [100]