Crystal structure and mass spectrum of µ3-oxo-hexakis(µ-trimethyl-acetato)-trismethanoltri-iron(III) chloride, a trinuclear basic iron(III) carboxylate

Abstract

The crystal structure of the title compound has been determined by single-crystal X-ray diffraction photography, and refined isotropically by the method of least squares to R 0·11 6, based on 552 independent reflections. There are two molecules in a hexagonal unit cell, space group P6₃, with a= 10·43(3) and c= 22·79(5)Å. The structure consists of cations [Fe₃O(piv)₆(MeOH)₃]⁺(piv = CMe₃·CO₂) lying on the three-fold axes, with chloride ions on the screw axes. The cation is analogous to that in the chromium(III) and iron(III) basic acetates, except for the rigorous three-fold symmetry and the fact that the central oxygen atom is displaced 0·24 Å from the Fe₃ plane. The mass spectrum is unusual in showing peaks due to ions containing more than three iron atoms, e.g. Fe₄O(piv)₆⁺ which appears in greater abundance than any trinuciear ion.