Finding a logical relation between the IC50 values of anticancer drugs and a computationally calculated physical quantity of them can be very useful in predicting and designing new drugs, reduces the time and cost and helps the society. In this work, we want to investigate the possible relation between the experimental IC50 values of two different series of drugs, with general formula [(NHC)M(L)](PF6) and [(NHC')M'(L')], and the calculated energies for (NHC)M–L and (NHC')M'−L' interactions, respectively, inside them. In above complexes NHC (NHC'), M (M') and L (L') refer to an N-hetrocyclic carbene ligand, a group 10 (11) metal ion and the second bonded ligand, respectively (illustrated in Schemes 1 and 2). Indeed, in the series of [(NHC)M(L)](PF6) complexes the NHC ligand, in [(NHC')M'(L')] ones the L' ligand and in both series of complexes the metal ion (M or M') is changed. All calculations were done at the PBE-D3/def2TZVP level of theory. The nature of (NHC)M–L and (NHC')M'−L' bonds was analyzed by utilizing natural bond orbital (NBO), atoms in molecules (AIM), energy decomposition analysis (EDA), and extended transition state natural orbital for chemical valence (ETS-NOCV). Fortunately, in all cases a good correlation between the IC50 values and the calculated interaction energies were observed.
