The performance of multiconfigurational second order perturbation theory has been analyzed for the description of the bonding in CuH, Cu₂, NiH, and Ni₂. Large basis sets based on atomic natural orbitals (ANOS) were employed. The effects of enlarging the active space and including the core-valence correlation contributions have also been analyzed. Spectroscopic constants have been computed for the corresponding ground state. The Ni₂ molecule has been found to have a 0_g⁺ ground state with a computed dissociation energy of 2.10 eV, exp. 2.09 eV, and a bond distance of 2.23 Å. The dipole moments of NiH and CuH are computed to be 2.34 (exp. 2.4 ± 0.1) and 2.66 D, respectively.