To gain a better understanding of the observed magnitude as well as the sign of D values for the studied complexes, we have analyzed the pattern of molecular d-orbitals splitting of these complexes obtained from AILFT analysis as shown in the top panel of Figure Here, the electron promotes to the states with different |m l | values and the energy difference between the ground and second excited state is quite large (Table ), hence, it gives a small positive contribution to the D value. Since the first excited state lies close to the ground-state, it governs the overall sign and magnitude of D leading to a high negative D value of -109.13 cm -1 for complex 1.