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Durham University

Department of Chemistry

Publication details for Dr Mark A. Fox

Kahlert,J., Stammler, H.-J. Neumann, B., Harder, R.A. , Weber, L. & Fox, M.A (2014). Crystal structures of the carborane dianions, [1,4-(PhCB10H10C)2C6H4]2- and [1,4-(PhCB10H10C)2C6F4]2-, and the stabilizing role of the para-phenylene unit on unusual 2n+3 SE clusters. Angewandte Chemie International Edition 53(14): 3702-3705.

Author(s) from Durham


While carboranes with 2 n+2 and 2 n+4 (n=number of skeletal atoms) skeletal electrons (SE) are widely known, little has been reported on carboranes with odd SE numbers. Electrochemical measurements on two-cage assemblies, where two C-phenyl-ortho-carboranyl groups are linked by a para-phenylene or a para-tetrafluorophenylene bridge, revealed two well separated and reversible two-electron reduction waves indicating formation of stable dianions and tetraanions. The salts of the dianions were isolated by reduction with sodium metal and their unusual structures were determined by X-ray crystallography. The diamagnetic dianions contain two 2 n+3 SE clusters where each cluster has a notably long carborane C–carborane C distance of ca 2.4 Å. The π conjugation within the phenylene bridge plays an important role in the stabilization of these carboranes with odd SE counts.