Synthesis, characterization, and study of octanuclear iron-oxo clusters containing a redox-active Fe4O4-cubane core

Baran, P., Boca, R., Chakraborty, I., Giapintzakis, J., Herchel, R., Huang, Q., McGrady, J. E., Raptis, R. G., Sanakis, Y. and Simopoulos, A. (2008) Synthesis, characterization, and study of octanuclear iron-oxo clusters containing a redox-active Fe4O4-cubane core. Inorganic Chemistry, 47(2), pp. 645-655. (doi: 10.1021/ic7020337)

Abstract

A one-pot synthetic procedure yields the octanuclear Fe-III complexes Fe-8(mu(4)-O)(4)(mu-PZ*)(12)X-4, where X = Cl and pz* = pyrazolate anion (PZ = C3H3N2-) (1), 4-Cl-pz (2), and 4-Me-pz (3) or X = Br and pz* = pz (4). The crystal structures of complexes 1-4, determined by X-ray diffraction, show an Fe4O4-cubane core encapsulated in a shell composed of four interwoven Fe(mu-pz*)(3)X units. Complexes 1-4 have been characterized by H-1 NMR, infrared, and Raman spectroscopies. Mossbauer spectroscopic analysis distinguishes the cubane and outer Fe-III centers by their different isomer shift and quadrupole splitting values. Electrochemical analyses by cyclic voltammetry show four consecutive, closely spaced, reversible reduction processes for each of the four complexes. Magnetic susceptibility studies, corroborated by density functional theory calculations, reveal weak antiferromagnetic coupling among the four cubane Fe centers and strong antiferromagnetic coupling between cubane and outer Fe atoms of 1. The structural similarity between the antiferromagnetic Fe-8(mu(4)-O)(4) core of 1-4 and the antiferromagnetic units contained in the minerals ferrihydrite and maghemite is demonstrated by X-ray and Mossbauer data.

• Item Type: Articles
• Keywords: ANION ATOMS BR CENTERS CL CLOSTRIDIUM-PASTEURIANUM CLUSTER CLUSTERS COMPLEX COMPLEXES CORE CRYSTAL Crystal structure Crystal structures CRYSTAL-STRUCTURE CRYSTAL-STRUCTURES CUBANE-LIKE DENSITY Density functional theory DIFFRACTION ELECTROCHEMICAL DETECTION ELECTRON-TRANSFER FE FE-III HYPERTHERMOPHILIC ARCHAEON IRON(III) COMPLEX METAL-SULFUR CLUSTERS MINERALS NMR OCTANUCLEAR ONE-POT PYROCOCCUS-FURIOSUS RAMAN RAMAN-SPECTROSCOPY REDUCTION SHELL SIMILARITY SINGLE-MOLECULE MAGNET SPECTROSCOPY STEREOCHEMICAL CONSEQUENCES Structure UNIT UNITS WEAK X-RAY X-ray diffraction X-RAY-DIFFRACTION
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: McGrady, Prof John
• Authors: Baran, P., Boca, R., Chakraborty, I., Giapintzakis, J., Herchel, R., Huang, Q., McGrady, J. E., Raptis, R. G., Sanakis, Y., and Simopoulos, A.
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: Inorganic Chemistry
• ISSN: 0020-1669