PBEPBE works in good way for metal complexes until Osmiun considering the basis set def2svp. The hybrid functional PBEPBE proposed by
Adamo et al. in conjunction with the basis set def2svp. The combination PBEPBE/def2svp has demonstrated to describe analogous systems with a
considerable accuracy. HPC is necessary for complexes with too many atoms but a single point could be done in a laptop, 100 atoms considering 1-3 metal centers if your starting point is from crystal data.