We have investigated the origin of single molecule magnetic behavior of a series of linear or This observation is rationalized based on different patterns of d-orbital splitting and their ground state occupancy. Moreover, the existence of multiple relaxation pathways with partial relaxation within ground state KDs for complex 2 and barrierless potential well triggering faster relaxation within the ground state KDs in complex 3 provides signatures for the absence of SIM behavior in these complexes. Thus, moderate magnitude of magnetic anisotropy and faster quantum tunneling of relaxation are found to co-exist in these complexes. Moreover, the experimentally synthesized complexes 4 and 5 are characterized with large magnetic anisotropy of -79.06 and -65.10 cm -1 but complex 5 exhibits multiple relaxation pathways with partial tunneling within the ground state KDs. Therefore, it is speculated to possess SIM behavior under applied field. However, complex 4 possessing Ising type anisotropy and TA-QTM provide the potential to behave as superior SIM under zero applied field. Moreover, complex 4 is the second Fe(I) complex to possess large ZFS value of -79.06 cm -1 followed by complex 1 (D=-109.13 cm -1 ) among