The wavefunction-based complete active space self-consistent field (CASSCF) calculations complemented by N-Electron valence state perturbation theory (NEVPT2) to capture dynamical correlations were performed on the most stable optimized geometries obtained from DFT. All the CASSCF/NEVPT2 calculations were performed in the high-spin state. The same basis set i.e., def2-TZVP for all the metals and the O atom while def2-SVP basis for C and H, as used in DFT was employed in all multireference calculations. The active space configuration encompasses five electrons in the five 3dorbitals of each spectator Fe atom, represented as (5,5) for one Fe and another (5,5) for the second Fe, alongside the n electrons in n singly-occupied orbitals (n,n) of the active metal, where n denotes the count of unpaired electrons. Additionally, the active space includes two electrons in a single orbital (2,1) from the carbon/hydrogen directly bonded to the central metal atom. Collectively, the baseline active space from the two Fe atoms and the carbon/hydrogen is standardized to (12,11), which then varies based on the active metal's electron configuration. For Fe 2 Ni and Fe 2 Cu with Ni and Cu contributing two and one unpaired electron respectively, the total active space expands to (14,13) and (13,12) for Fe 2 Ni and Fe 2 Cu respectively. For a Fe 3 system, considering four unpaired electrons and one doubly occupied orbital from the third Fe, the active space comprises of (18,16). For the cases where the spectator atom is varied, the active space consists of two electrons in two orbitals (2,2) of the active Ni atom and two electrons in one orbital