In the case of complexes 2 and 5, the computed transveral-magnetic-moment is 0.14 and 0.1 respectively in the ground state suggesting partial QTM to be operative through the ground state KDs. The larger magnitude of transition-magnetic-moment matrix elements of 1.3 and 1.1 for 2 and 5 respectively for the first excited state for both the complexes mark the major relaxation to proceed through this state. Besides, the off-diagonal matrix elements between the ground and first excited KDs of opposite magnetization are also moderate (0.42 and 1.0) opening up further relaxation pathways via Orbach relaxation. Therefore, for these complexes, multiple relaxation pathways are operational. On the other hand, for complex 3, the m J = ±1/2 is the ground state with a barrierless potential well which is also signified by the high magnitude of transition-magnetic-moment matrix element i.e., 1.8, suggesting faster relaxation within the ground state for this complex. These relaxation pathways provide the plausible reason for no SIM behaviors under any applied field for complexes 2 and 3 as observed by Meng et al. Since for complex 2, due to multiple relaxation pathways i.e., partial QTM through the ground-state KDs and Orbach relaxation, the complex shows absence of SIM behavior. In contrast, complex 3 possessing barrierless potential well leads to relaxation within the ground-state KDs. Thus, both the complexes do not show any signatures of SIM behavior.