  We investigate the properties of clusters formed from two connected
$\mathrm{Ge_{m}}$ cage-like clusters, such as experimentally synthesized
$\mathrm{Au_3Ge_{18}^{5-}}$, using first-principles DFT methods. We focus
particularly on $\mathrm{Au_nGe_{12}^{q-}}$ formed from $\mathrm{Ge_{6}}$,
where $n=0-3$ and $q=0,2$. We examine the geometries, electronic structure, and
thermal excitations of these clusters using the SIESTA code, where we test
stability using short molecular dynamics simulations. Our examination of
intercluster bridges between $\mathrm{Ge_{m}}$, formed of either Ge-Ge or Au-Ge
bonds, indicates that the overlap of interacting molecular orbitals of
$\mathrm{Ge_{m}}$~can either bind a cluster together or tear it apart depending
on the orientation of the bridging atoms with respect to the cages. We
characterize the properties of stable isomers of neutrally charged
$\mathrm{AuGe_{12}}$ and $\mathrm{Au_2Ge_{12}}$, seeing that radially directed
molecular orbitals stabilize $\mathrm{AuGe_{12}}$ while a geometric asymmetry
stabilizes $\mathrm{Au_2Ge_{12}}$ and $\mathrm{Au_3Ge_{18}}$. We examine a
two-dimensional $_2^\infty[\mathrm{Au_2Ge_{6}}]$ structure, finding it more
stable than other periodic $[\mathrm{Au_nGe_{6}}]$ subunits. We observe no
stable neutral isomers of $\mathrm{Au_3Ge_{12}}$, but see that additional
charge supports isomers of both $\mathrm{Au_2Ge_{12}}$ and
$\mathrm{Au_3Ge_{12}}$.
