Table 4. Binding Energy Trend (E_b^Ni2+ – E_b), Using Different Levels of Theory, of Benzene Coordinated with Fe²⁺ and Ni²⁺.

level of theory	EbNi2+ - Eb (eV)
B3LYP-D2/6-311++G(2d,2p)78	2.97
ωB97X-D/6-311++G(2d,2p)78	2.82
MP2/6-311++G(2d,2p)78	2.84
PBE-D4/CP-DZPa	2.39
DRSLL/CP-DZPa	0.51
CCSD(T)/6-311++G(2d,2p)78	2.53

^aThis work.