Triethanolaminate iron perchlorate revisited: change of space group, chemical composition and oxidation states in [Fe 7 7 (tea) 3 3 (tea‐H) 3 3 ](ClO 4 4 ) 2 2 (tea‐H 3 3 is triethanolamine)

摘要

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 7 (C 6 H 12 NO 3 ) 3 (C 6 H 13 NO 3 ) 3 ](ClO 4 ) 2 or [Fe 7 (tea) 3 (tea‐H) 3 ](ClO 4 ) 2 (tea‐H 3 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 I 2 1 3 and is reinvestigated in the present study. We find a new space‐group symmetry of Pa 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 II and three Fe III centres. Symmetry relationships between the two space groups and the average supergroup Ia are discussed in detail.