The paper reports computations for Mg@C74, Ca@C74, Sr@C74, Ba@C74, and all lanthanoids, based on encapsulation into the only C74 IPR (isolated pentagon rule) cage, and for Al@C82, Sc@C82, Y@C82 and La@C82 based on encapsulation into the IPR C2v C82 cage. Their structural and energetic characteristics are used for evaluations of the relative production yields, employing the encapsulation Gibbs-energy terms and saturated metal pressures.
It is moreover shown that the encapsulation potential-energy changes in such series can be well related to the mere ionization potentials of the free metal atoms.