Knowledge Bank

Ions of abundant metals, including Na$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$, K$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$, Mg$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$, Ca$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$ and Fe$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$, are likely to play an important role in the chemical evolution of metal-containing interstellar and circumstellar environments. The ionic reaction networks include a variety of efficient radiative association, ligand-switching, clustering and recombination processes. High-level ab initio calculations, using the CP-dG2thaw method and related approaches, are combined here with VTST computations of reaction kinetics to explore the reactivity of the atomic metal ions and metal-containing molecular ions with abundant neutrals. The likely composition of the metal-containing populations and the accompanying formation of neutral species like MNC, MCN and MC$3$N 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.