Triethanolaminate iron perchlorate revisited: change of space group, chemical composition and oxidation states in [Fe7(tea)3(tea-H)3](ClO4)2 (tea-H3 is tri­ethano­lamine)

Abstract

The X-ray crystal structure of tris­[N-(2-hy­droxy­eth­yl)-2,2′-imino­di­ethano­l­ato]tris­(2,2′,2′′-nitrilo­tri­ethano­lato)tetra­iron(II)triiron(III) bis­(perchlorate), [Fe7(C6H12NO3)3(C6H13NO3)3](ClO4)2 or [Fe7(tea)3(tea-H)3](ClO4)2 (tea-H3 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 I213 and is reinvestigated in the present study. We find a new space-group symmetry of Pa\overline{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 FeII and three FeIII centres. Symmetry relationships between the two space groups and the average supergroup Ia\overline{3} are discussed in detail.