The role of the donor-acceptor (bonding-antibonding) interactions is exemplified by two limiting cases: ScPhos and ZnPhos (Fig. ). In the case of the substitutionally-doped ZnSPhos system, the interaction shows phosphorene→metal electron delocalization of the BD→pLP* and LP→pLP* type (Fig. , right); this is the P-P bond, and 3p lone pair orbitals of phosphorene delocalize their electrons to the unoccupied 4p orbitals of Zn. The mismatching between the energies of the 4p orbitals of Zn with the 3d orbitals of phosphorene must decrease the stability gained by this electron delocalization, explaining the lowest stability gained by charge transfer (ECT=-4.65 eV) among all the substitutionally-doped systems. Additionally, the electron configuration of Zn ([Ar]3d 10 4s 2 ) indicates electron filled 4s and 3d orbitals; these electrons can be repulsive for electrons delocalized to 4p orbitals of Zn, decreasing the ECT contribution due to steric effects. In this framework, the limit case is the substitutionally-doped ScSPhos system, which