QM evaluation of the intramolecular aromatic π-π interactions of Ir(I) complex transition states

•The intramolecular aromatic π-π interactions were investigated by high-level quantum mechanical methods in the transition states of Ir(I)-catalyzed alkane CH activation.•The truncated phenyl radical model was applied for the computation of intramolecular π-π interactions.•The intramolecular π-π interaction forces were found to be slightly repulsive.•Comparison of calculation results were made between restricted open shell and unrestricted open methods.•The DFT M06HF functional provided a reasonable interaction energy compared with that of CCSD(T) method.