A variety of complexes - a subset of metallaborane - are known with one or two dicarbollide ligands.  An example of a 1:1 complex is [Mn(CO)(η-7,8-CBH)].
Most heavily studied are complexes with two dicarbollide ligands, especially sandwich complexes. Thus, these are prepared by salt metathesis reactions, as illustrated by the synthesis of the ferrocene  analogue:
:2 NaCBH  +  FeCl  →   Na[Fe(CBH)]  +  2 NaCl
These bisdicarbollide dianions are often readily oxidized. Fe(III), Co(III), Ni(III), and Ni(IV) derivatives are known.  In some cases, the oxidation induces rearrangement of the CB cage to give complexes where the carbon centers are nonadjacent.