ABSTRACT The recent synthesis of diaminomethane ((NH2)2CH2) under simulated interstellar conditions implies that this molecule is likely present in the interstellar medium (ISM), and this work provides the highly accurate quantum chemically computed rotational constants and IR frequencies for comparison to experiment that may aid in its potential future detection. This simplest geminal diamine of prebiotic note has a transition for its ν18 fundamental frequency at 702.5 cm−1 (14.23 μm) with an intensity on level with that of the antisymmetric stretch in carbon dioxide. Additionally, its 1.72 D dipole moment for the most stable C2v conformer should make it detectable with radiotelescopes as well. The C2 conformer may also be detectable in similar regions where the C2v form is present, but only warmer or higher-energy regions will allow for possible observation of the C1 conformer. In any case, rotational constants for these other two conformers are also provided in addition to the full set of fundamental vibrational frequencies for the C2v conformer. These data will assist with further laboratory classification and possible interstellar detection of this prebiotic molecule.