program package utilizing the Vienna Scientific Cluster (VSC 4) in part. Electronic ground state calculations, including geometry optimizations, frequencies and transition-state searches were carried out with density functional theory (DFT) utilizing ORCA and the TPSSh meta-hybrid functional 66 together with Grimme's D3 dispersion correction and Ahlrichs' def2-SVP basis set. The resolution of identity (RI) approximation was used along with the corresponding auxiliary basis sets to accelerate the calculations. Gibbs free energies at 298 K were calculated using the rigid-rotor harmonic oscillator (RRHO) approximation as implemented in ORCA and real frequencies below 100 cm -1 were raised to 100 cm -1 to improve accuracy. Final single-point energies were calculated with TPSSh/def2-TZVP/D3 or OPBE/def2-TZVP/D3 70,71 on already obtained geometries, while Gibbs energies were obtained by adding zero point energies, thermal and entropic corrections at 298 K. For geometry optimizations and single-point calculations implicit solvation was included via the CPCM model and dichloromethane as solvent. Transition states were localized with the help of the nudged elastic band (NEB) method as implemented in ORCA and confirmed to be first-order saddle points by analysis of the Hessian. Intrinsic reaction coordinate (IRC) calculations have been employed to verify the correct assignment of transition states by following the eigenvector of the corresponding imaginary frequency, starting from the TS structures and connecting with reactants and products. Minimum Energy Crossing Points (MECP) were calculated using the algorithm implemented in ORCA and the SurfCrossOpt keyword. DLPNO-CCSD(T) calculation were performed on previously obtained TPSSh-geometries, using the def2-TZVP basis set and a converged BP86 UKS reference wave function. For the sake of completeness, it should also be mentioned that the wave functions of all Mn complexes were checked for internal stability: This revealed that the S = 0 species derived from 2-Mn exhibit a slight instability towards a unrestricted Kohn-Sham (UKS) wave function. However, the elec-tronic energy differences are negligible (< 1 kcal/mol). Energy Decomposition Analysis (EDA) was specifically performed in ADF using the TPSSh functional together with the TZ2P basis set and no frozen core orbitals. The numerical quality was set to "very good", and the scalar relativistic effects were accounted for using the Zeroth-Order Regular Approximation (ZORA). For the interaction between triplet fragments, the spin polarization was set to +2 for one fragment and -2 for the other to ensure anti-parallel spins during Energy Decomposition Analysis. Orbital plots and graphics were visualized and generated with ChemCraft. Associated Content