Experimental charge density in an oxidized trinuclear iron complex using 15 K synchrotron and 100 K conventional single-crystal X-ray diffraction.

The experimental electron density distribution in a crystal consisting of the simplest conceivable trinuclear carboxylate-bridged iron-mu3-oxo dianion with two alpha-picolinium cations has been determined using both synchrotron (15 K) and conventional (100 K) X-ray diffraction data. The constituent trinuclear oxo-centered molecule consists of six mu2-bridging formate groups between the iron pairs, while the axial ligand for all iron atoms is another formate group. The compound {[FeO(HCOO)5(HCOO)3]2-.