A Novel Nonairon(III) Citrate Complex: A "Ferric Triple-Decker"

Avi Bino*, Itzhak Shweky, Shmuel Cohen, Erika R. Bauminger, Stephen J. Lippard

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

69 Scopus citations

Abstract

The novel nonairon(III) citrate complex [Fe9O(cit)8(H2O)3]7- (3) [cit = C(O-)(COO-)(CH2COO-)2] was prepared as its neocuproinium salt by reacting ferric nitrate, sodium citrate, and neocuproine (neo; 2,9-dimethyl-1,10-phenanthroline) in a 1:1:1 ratio in aqueous solution. The compound (Hneo)7·3·neo·61H2O crystallizes in the monoclinic space group P21/c with unit cell parameters of a = 21.910(3) Å, b = 25.788(5) Å, c = 39.653(6) Å, β = 99.47(1)°, V = 22 099(7) Å3, and Z = 4. The anionic complex consists of three parallel triangular Fe3 units, 5.6 Å apart, forming a slightly distorted trigonal prism. The outer two units are connected by three bridging tetradentate cit4- ligands to the central one. and each of the terminal Fe3 units is capped by another cit4- ligand. The central Fe3 unit has the oxo-bridged basic iron carboxylate structure, whereas the two terminal ones have a "voided cubane" structure with an {Fe3O4} core. Mössbauer spectra are composed of two subspectra ("a" and "b") with intensity ratio 2:1, reflecting the existence of two inequivalent trivalent iron sites. Subspectra "a" are assigned to the three equivalent iron atoms of the terminal Fe3 units, and subspectra "b" to the three equivalent iron atoms of the central unit.

Original languageEnglish
Pages (from-to)5168-5172
Number of pages5
JournalInorganic Chemistry
Volume37
Issue number20
DOIs
StatePublished - 1998

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