Abstract:In this contribution, we present the first crystal structure of iron(III) salicylate without additional counterions. The octahedral complex contains two salicylate and two water molecules as ligands. One salicylate is mono-anionic while the other is di-anionic. Because of the centrosymmetry of the complex, the acidic hydrogen atom is disordered on the midpoint between two salicylate oxygens. The structure determination of the tiny crystal indicates the presence of reticular twinning. The structure solution of the twin is shown and an explanation based on the crystal packing is provided.

Two independent copper(II) cations with coordination numbers of 4 and 6 are bridged by dianionic salicylate anions into chains extending parallel [001]. O—H⋯O hydrogen-bonding inter­actions involving both the coordinating and the lattice water mol­ecules result in the formation of a three-dimensional network.

The X-ray crystal structure of tris[N-(2-hydroxyethyl)-2,2'-iminodiethanolato]tris(2,2',2''-nitrilotriethanolato)tetrairon(II)triiron(III) bis(perchlorate), [Fe(CHNO)(CHNO)](ClO) or [Fe(tea)(tea-H)](ClO) (tea-H is triethanolamine), is known from the literature [Liu et al. (2008). Z. Anorg. Allg. Chem. 634, 778-783] as a heptanuclear coordination cluster. The space group was given as I23 and is reinvestigated in the present study. We find a new space-group symmetry of Pa-3 and could detect O-H hydrogens, which were missing in the original publication. Consequences on the Fe oxidation states are investigated with the bond-valence method, resulting in a mixed-valence core of four Fe and three Fe centres. Symmetry relationships between the two space groups and the average supergroup Ia-3 are discussed in detail.