All calculations were performed using ORCA 4 1 with models initially geometry optimised in the fully ferromagnetic state of (Mn IV )4. Optimisation calculations used the BP86 functional with the zeroth-order regular approximation (ZORA) Hamiltonian applied to include scalar relativistic effects. ZORA versions of the def2-SVP basis sets were used for C and H atoms. ZORA versions of the def2-TZVP basis set with f functions removed were used for all other atoms. The resolution of identity approximation (RI-J) for coulomb integrals, along with the decontracted general Weigend auxiliary basis sets were used. Dispersion corrections proposed by Grimme with Becke-Johnson damping (D3BJ) were included. The conductor-like polarizable continuum model (CPCM) with a dielectric constant ε = 8.0 was applied in all calculations. Increased integration grids (Grid6 and IntAcc 6 in ORCA convention) and tight SCF convergence criteria were used. All terminal carbon atoms were constrained during optimisation calculations. Heisenberg exchange coupling constants (Jij) and hyperfine couplings were calculated using the broken symmetry DFT (BS-DFT) methodology proposed and justified by Pantazis et al. The hybrid meta-GGA TPSSh functional was used for BS-DFT and EPR calculations. The chain of spheres (RIJCOSX) approximation to exact exchange was applied along with the same decontracted auxillary basis sets involved in geometry optimization calculations. ZORA versions of the def2-TZVP basis set with f functions removed was used for all atoms. Initial BS guesses were constructed using the 'flipspin' feature of ORCA. Convergence to the correct BS and HS states in all calculations was confirmed by examination of the calculated Mulliken spin populations. The 'orca_eca' module within ORCA was used to calculate HDvV spin ladders and spin projection coefficients. Calculation of the hfcs used basis sets for Mn, N and O atoms based on SARC def2-TZVP which have been developed by Neese et al. These basis sets contained fully decontracted s-shells with three additional steep primitives added to the core, in addition to this the def2-TZVP(-f) basis set was used for all other atoms. Increased integration grids were used for Mn, N and O, these were set to 11, 9 and 9, respectively. Picture change effects were applied for the calculation of hfcs. Mn isotropic hfcs were scaled by an empirically derived factor of 1.7 to account for well known deficiencies of the Fermi contact term when calculated using DFT methods. For the S3 state of the WOC with Mn1-4 oxidation states IV-IV-IV-IV, a local Sz of 3/2 for the d ion Mn(IV) is used. The high-spin determinant can be described as |+3/2, +3/2, +3/2, +3/2> (or "αααα", MS = 12) and six BS determinants were created by inverting local spins of Mn ions. For example, |+3/2, +3/2, +3/2, -3/2> ("βααα", MS = 3) or |+3/2,-3/2, -3/2, +3/2>