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Unique collaboration results in cover for Angewandte Chemie

vollhardt

by Michael Barnes

When Peter Vollhardt heard that a molecule he had synthesized would appear on the cover of Angewandte Chemie, he began to look for a suitable background image. He didn't have to look far. The image was hanging in his living room, a painting by artist (and spouse) Marie Sat. This unique collaboration has resulted in the cover for the March 3rd issue of the journal.

The molecule, technically a ferrocene-substituted cyclopentadienyl metal complex, is the result of a decade of work in Vollhardt's lab. It is a beautifully symmetrical combination of metal atoms and carbon pentagons, a five-pointed molecular version of a child's pinwheel.

moleculeOn each of the tips of the pinwheel resides a molecule called ferrocene, an iron-carbon 'sandwich' first synthesized in 1951. Each sandwich consists of two flat five-sided carbon rings surrounding an atom of iron. The synthesis of ferrocene over 50 years ago led to an explosion of interest in metal-carbon bonds and helped form the basis for the field of organometallic chemistry.

Each of the five ferrocene molecules in Vollhardt's creation is bonded to a central pentagon of carbon atoms. However, the central carbon pentagon is not part of an iron-carbon sandwich. Rather, this central ring is a ligand, sharing electrons with an atom of manganese that is itself bonded on its other side to a tripod of three carbon monoxide molecules (see illustration).

Vollhardt credits the creation of this new metal complex (and several related structures) to the hard work of his lab group, especially post-doc Yong Yu. The research was supported by the U.S. Department of Energy.

journal cover

Chemists have been delighted by this new metal complex, which was featured in Nature and Chemical and Engineering News (C&EN), along with the cover story in Angewandte Chemie. Guy Bertrand of the University of California, Riverside, told C&EN that this new metal complex is "just amazing." "I am quite convinced that very unusual chemistry will be found with these molecules," he adds.

This new molecule and its relatives may form the bases for materials with unusual electronic and magnetic properties, and may be useful as new catalysts. Moreover, if the ten hydrogens close to the central five-membered ring are stripped away by 'annealing' and the peripheral pentagons thus joined by five new carbon-carbon bonds, the result would be yet another elusive molecule—the 'half buckyball,' or semibuckminsterfullerene (C30H10). These half buckyballs could serve as open-faced models for the end caps of carbon nanotubes.

With the synthesis of the metal complex, Vollhardt and colleagues have created a molecule that does not exist in nature. "Our work lies in the realm of creating something new, something interesting or challenging," says Vollhardt. "We hope other researchers can take our results and develop them into useful products. The symmetry of the molecule, like the painting in the cover illustration, makes it aesthetically pleasing, and we suspect this symmetry will give it unique chemical properties as well."

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