Dimethyloxonium and Methoxy Derivatives of nido-Carborane and Metal Complexes Thereof

9-Dimethyloxonium, 10-dimethyloxonium, 9-methoxy and 10-methoxy derivatives of nido-carborane (9-Me2O-7,8-C2B9H11, 10-Me2O-7,8-C2B9H11, [9-MeO-7,8-C2B9H11]−, and [10-MeO-7,8-C2B9H11]−, respectively) were prepared by the reaction of the parent nido-carborane [7,8-C2B9H12]− with mercury(II) chloride in a mixture of benzene and dimethoxymethane. Reactions of the 9 and 10-dimethyloxonium derivatives with triethylamine, pyridine, and 3-methyl-6-nitro-1H-indazole result in their N-methylation with the formation of the corresponding salts with 9 and 10-methoxy-nido-carborane anions. The reaction of the symmetrical methoxy derivative [10-MeO-7,8-C2B9H11]− with anhydrous FeCl2 in tetrahydrofuran in the presence of t-BuOK results in the corresponding paramagnetic iron bis(dicarbollide) complex [8,8′-(MeO)2-3,3′-Fe(1,2-C2B9H10)2]−, whereas the similar reactions of the asymmetrical methoxy derivative [9-MeO-7,8-C2B9H11]− with FeCl2 and CoCl2 presumably produce the 4,7′-isomers [4,7′-(MeO)2-3,3′-M(1,2-C2B9H10)2]− (M = Fe, Co) rather than a mixture of rac-4,7′- and meso-4,4′-isomers.

Teaching an old dog new tricks: new directions in fundamental and applied closo-carborane anion chemistry

In this feature article we cover new directions in the fundamental and applied chemistry of the closo-carborane anions [HCB11H11]−1 and [HCB9H9]−1, including energy storage applications, ionic liquids, anionic carborane fused heterocycles/radicals, ligand substituents, and ligands for catalysis and coordination chemistry.

Below the 12-vertex: 10-vertex carborane anions as non-corrosive, halide free, electrolytes for rechargeable Mg batteries

The synthesis and application of the first high voltage, non-corrosive, Mg battery electrolyte based on small carborane anions are reported. This electrolyte displays equal oxidative stability compared to its larger 12-vertex cousin, but is more cost effective to prepare.

Inductive effects of 10 and 12-vertex closo-carborane anions: cluster size and charge make a difference

The inductive effects of 10 and 12-vertex closo-carborane anion ligand substituents are elucidated for the first time. It is found that both of these cluster substituents are potent electron donating groups, which is in contrast to C-functionalized o-carborane. The fact that the 10-vertex cluster displays the strongest electron donating ability can be rationalized by its charge and size.