Structural chemistry of halogenated monocarbaboranes: the extended structures of Cs[1-HCB9H4Br5], Cs[1-HCB11H5Cl6] and Cs[1-HCB11H5Br6]

The crystal structures of the Cs+ salts of the halogenated monocarbaborane anions [closo-1-HCB9H4Br5](-), [closo-1-HCB11H5Cl6](-) and [closo-1-HCB11H5Br6](-) have been determined. The structures show two-dimensional extended-sheet or three-dimensional lattice structures and feature unusual distorted cuboctahedral and tetrakis hexahedral coordination geometries about Cs+. Incidental to the structural work, new convenient preparations of the precursive non-halogenated monocarbaborane anions [closo-1-HCB9H9](-) and [closo-1-HCB11H11](-) are presented.