  We demonstrate cryogenic buffer-gas cooling of gas-phase methyltrioxorhenium
(MTO). This molecule is closely related to chiral organometallic molecules
where the parity-violating energy differences between enantiomers may be
measurable. The molecules are produced with a rotational temperature of
approximately 6~K by laser ablation of an MTO pellet inside a cryogenic helium
buffer gas cell. Facilitated by the low temperature, we demonstrate absorption
spectroscopy of the 10.2~$\mu$m antisymmetric Re=O stretching mode of MTO with
a resolution of 8~MHz and a frequency accuracy of 30~MHz. We partially resolve
the hyperfine structure and measure the nuclear quadrupole coupling of the
excited vibrational state.
