New SubmissionDensity-Functional Calculations on the Spin Dependence of Aminoferrocene on Graphene

Recently, El-Gendy et al. reported strong magnetism in aminoferrocene–graphene molecular magnets [APL 122, 241903 (2023)]. They followed up with a paper analyzing the possibility of a chiral aminoferrocene-hexagon [APL 124, 111903 (2024)]. These results indicate that ferrocene changed its magnetic and electronic properties through addition of functional groups like amino, oxygen exposure to the graphene substrate. The electronic and vibrational spectra of aminoferrocene as a function of charge and spin is interesting because the energy of the neutral molecule exhibits a tiny Hund’s-rule high-spin preference implying vibrational zero-point energies could impact the energy splitting. The charged systems exhibit strong magnetic anisotropy which depends on the degree of ionicity and spin of the system. When the chiral complex is placed above a graphene substrate, the charge transfer depends on the relative electronegativities of the substrate and the ring and the magnetic strength ultimately depends on the charge state. We use density functional theory (DFT) to investigate the electronic and vibrational spectra of aminoferrocene as a function of spin (S=1, 2) and charge (neutral, cationic, anionic). Vibrational modes are examined to determine whether spin and charge states can be distinguished spectroscopically. The charge transfer is quantified by using Janak’s theorem and Mulliken’s formula. We analyze both single aminoferrocenes and chiral aminoferrocene hexagonal rings on graphene.