Abundances calculated with the chemical model for Mg- and Na-bearing cyanides in IRC +10216. The initial abundance of Mg and the branching ratios of the dissociative recombination of metal-bearing cation complexes were chosen to reproduce the observed values. For example, the observed column density of MgNC is 1.3 × 10¹³ cm⁻² (Cabezas et al. 2013) while the calculated value, evaluated as twice the radial column density, is 1.1 × 10¹³ cm⁻². Closed shell species, such as HMgNC, HMgC₃N, NaCN, and NaC₃N, extend further than open shell ones because we assume that they do not react with H atoms and electrons.