Main Group Metal Ion Chemistry in Cold Interstellar and Circumstellar Environments Available to Purchase

High‐level ab initio calculations, using the CP‐dG2thaw method and related approaches, are combined with VTST computations of radiative association rate coefficients to explore the reactivity of atomic metal ions and metal‐containing molecular ions with abundant interstellar and circumstellar neutrals. Consequences of the calculated energetics and kinetics of the metal ion / ligand chemistry are surveyed with particular reference to the refractory metals Mg and Ca. The likely composition of the metal‐containing populations and the accompanying formation of neutral species like MNC, MCN and MC₃N are examined for three different C‐rich environments, typified by the cold dark interstellar cloud TMC‐1, the outer circumstellar envelope of the AGB star IRC+10216 and the post‐AGB object CRL 618, and are discussed with reference to molecular detections within these three objects.