Cobalt ionic liquids with highly efficient and reversible absorption of NH ₃ through Lewis acid–base and hydrogen bond interactions were designed.

A quasi-planar member of the so-called ‘Wankel motor’ family, B₁₈²⁻, is found.

Several of the lowest energy structures of small and medium sized boron clusters are two-dimensional systems made up of a pair of concentric rings. In some cases, the barriers to the rotation of one of those rings relative to the other are remarkably low. We find that a combination of electronic and geometrical factors, including apparently the relative sizes and symmetries of the inner and outer rings, are decisive for the diminished barriers to in-plane rotation in these two dimensional clusters. A sufficiently large outer ring is important; for instance, expansion of the outer ring by a single atom may reduce the barrier significantly. A crucial factor for an apparent rotation is that the σ-skeleton of the individual rings remains essentially intact during the rotation. Finally, the transition state for the rotation of the inner ring comprises the transformation of a square into a diamond, which may be linked to a mechanism suggested decades ago for the isomerization of carboranes and boranes.

B ₁₂ is a rigid cluster with a high inner ring rotational energy barrier. However, doping it with Ir lowers the barrier significantly, transforming the IrB ₁₂ ⁻ cluster in a Wankel motor.