  Context. The detection of NH2CH2CH2OH (ethanolamine) in molecular cloud
G+0.693-0.027 adds an additional player to the prebiotic molecules discovered
so far in the interstellar medium (ISM). As this molecule might be formed
through condensed-phase hydrogenation steps, detecting one or more of the
molecules involved might help to elucidate the chemical pathway leading to its
production. Aims. The chemical path involves the formation of four chemical
species. In this work, we study the energies of the isomers involved, indicate
the best candidates for detection purposes, and provide the distortion
constants of the most energetically favoured isomers undetected so far.
Methods. We used highly accurate CCSD(T)-F12/cc-pCVTZ-F12 computations to
predict the lowest energy isomers as well as their spectroscopic constants,
taking corrections for core electron correlation and scalar relativity into
account. Results. We studied 14 isomers. We find that the lowest energy isomer
proposed in previous studies is not the actual minimum. We provide a set of
rotational and distortion constants of the two new most stable isomers together
with their fundamental vibrational frequencies in order to guide the search for
these important astrochemical precursors of prebiotic molecules in the ISM.
