The quantum chemical calculations for investigating the structural and electronic properties of phenPer and Rh III phenPer were performed with the Gaussian 16 program. Initially, the angle between the perylene (Per) and phenanthroline (phen) moiety of phenPer was scanned to find a fully relaxed equilibrium geometry of phenPer. That geometry was employed in the optimization of the structure of the respective Rh III complex (Rh III phenPer). The optimized singlet structures were obtained at the density functional level of theory (DFT) by means of the B3LYP XC functional. The def2-SVP basis as well as the respective core potentials (Rh) were applied for all atoms. A vibrational analysis was performed to verify that a minimum on the potential energy (hyper-)surface (PES) was obtained.