  We report on the high pressure synthesis of BiMn$_7$O$_{12}$, a manganite
displaying a "quadruple perovskite" structure. Structural characterization of
single crystal samples shows a distorted and asymmetrical coordination around
the Bi atom, due to presence of the $6s^{2}$ lone pair, resulting in
non-centrosymmetric space group Im, leading to a permanent electrical dipole
moment and ferroelectric properties. On the other hand, magnetic
characterization reveals antiferromagnetic transitions, in agreement with the
isostructural compounds, thus evidencing two intrinsic properties that make
BiMn$_7$O$_{12}$ a promising multiferroic material.
