Dichloro(4,10-dimethyl-1,4,7,10-tetraazabicyclo[5.5.2]tetradecane)iron(III) hexafluorophosphate

Abstract

The title compound, [FeCl2(C12H26N 4)]PF6, is the first mono-nuclear Fe3+ complex of an ethylene cross-bridged tetraazamacrocycle to be structurally characterized. Comparison with the mononuclear Fe2+ complex of the same ligand shows that the smaller Fe3+ ion is more fully encapsulated by the cavity of the bicyclic ligand. Comparison with the μ-oxo dinuclear complex of an unsubstituted ligand of the same size demonstrates that the methyl groups of 4,10-dimethyl-1,4,7,10-tetraazabicyclo[5.5.2]tetradecane prevent dimerization upon oxidation of the metal centre. Nax-Fe 3+-Nax bond angles (ax is axial), and thus the degree of encapsulation by the ligand, are quite different between the mononuclear and dinuclear μ-oxo species, which is probably the consequence of steric considerations. © 2006 International Union of Crystallography.