  Chemical bonding in 2D layered materials and van der Waals solids is central
to understanding and harnessing their unique electronic, magnetic, optical,
thermal and superconducting properties. Here we report the discovery of
spontaneous, bidirectional, bilayer twisting (twist angle ~ 4.5{\deg}) in the
metallic kagom\'e MgCo6Ge6 at T = 100(2) K via X-ray diffraction measure-ments,
enabled by the preparation of single crystals by the Laser Bridgman method.
Despite the appearance of static twisting on cooling from T ~ 300 K to 100 K,
no evidence for a phase transition was found in physical properties
measurements. Combined with the presence of an Einstein phonon mode
contribution in the specific heat, this implies that the twisting exists at all
temperatures but is thermally fluctuating at room temperature. Crystal Orbital
Hamilton Population analysis demonstrates that the cooperative twisting between
layers stabilizes the Co-kagom\'e network when coupled to strongly bonded and
rigid (Ge2) dimers that connect adjacent layers. Further modelling of the
displacive disorder in the crystal structure shows the presence of second,
Mg-deficient, stacking sequence. This alternative stacking sequence also
exhibits inter-layer twisting, but with a different pattern, consistent with
the change in electron count due to removal of Mg. Magnetization, resistivity,
and low-temperature specific heat measurements are all consistent with a Pauli
paramagnetic, strongly correlated metal. Our results provide crucial insight
into how chemical concepts lead to interesting electronic structures and
behaviors in layered materials.
