What is it about?
This paper describes the synthesis and structural characterization of molecular crystals made from iron-linked carbon spheres, known as metallacarboranes. These spherical carbon-based cages coordinate to an iron atom, forming a unique sandwich-like complex. When combined with an electron-accepting quinone molecule, the system forms a charge-transfer salt—an organized material where positive and negative species alternate in layered structures. Using X-ray crystallography, spectroscopy, and magnetometry, the study shows how oxidation changes the structure and how the resulting material exhibits weak magnetic interactions but no electrical conductivity. These results provide insights into how carbon-based molecular building blocks can be used to create materials with distinct magnetic and electronic behavior.
Featured Image
Photo by benjamin lehman on Unsplash
Why is it important?
This study provides the first crystal structure of a cationic bis(carborane) iron complex, offering direct insight into how molecular structure adapts upon oxidation. It also reveals how weak electrostatic and hydrogen bonding interactions between the iron–carbon spheres and quinone radicals organize the material into layered molecular crystals. Although the resulting compound is not electrically conductive, it demonstrates subtle magnetic behavior and serves as a model for designing functional molecular materials. The work contributes to the broader effort of engineering redox-active solids from spherical carbon-based units and radical anions—an approach relevant to future applications in molecular electronics and magnetic materials.
Perspectives
This was one of my first publications involving the characterization of carbon-based molecular materials, and it sparked a long-standing interest in the structure–function relationships of such systems. The paper captures an intriguing facet of functional materials—how spherical carbon cages can shape the solid-state properties of a molecular crystal through subtle redox and packing effects. It also reminds me of the close and productive collaboration with my direct bench colleague during my time in London, where daily discussions at the lab bench often led to deeper insights and unexpected results. Looking back, this study laid part of the foundation for my later work in carbon-centered chemistry and molecular materials design.
Prof. Dr. Thomas Ernst Müller
Ruhr-Universitat Bochum
Read the Original
This page is a summary of: Synthesis and structure of a charge-compensated ferracarborane, commo-[3,3′-Fe{4-(Me2S)-1,2-C2B9H10}2], and its charge-transfer salt with 2,3-dichloro-5,6-dicyano-p-benzoquinone, Journal of the Chemical Society Dalton Transactions, January 1994, Royal Society of Chemistry,
DOI: 10.1039/dt9940001735.
You can read the full text:
Resources
Contributors
The following have contributed to this page
