We accept in this work the reaction mechanism suggested in prior studies for aliphatic C-H fluorination with Mn complexes. In the resting state (1), the catalyst consists of Mn(III) coordinated to tetramesitylporphyrin (TMP) in the equatorial plane and fluoride in an axial position, with the other axial position being vacant (Figure ). Oxidation of this resting state intermediate results in a highly reactive oxomanganese species (2), Mn(V)=O(TMP)F (Figure ). This reactive Mn(V)-oxo intermediate abstracts a hydrogen atom from the substrate to form Mn(IV)-hydroxo intermediate (3), Mn(IV)(OH)(TMP)F, and a radical located on a carbon atom of the substrate (Figure ). The next step involves the formation of a difluoro intermediate (4), Mn(IV)(TMP)F2, by replacing OH with F in the catalyst in the reaction with AgF (Figure ). The fluoride in the axial position of the Mn(IV)(TMP)F2 intermediate then combines with the substrate radical to form the fluorinated product. This step is believed to be rate-limiting in the mechanism of the fluorination reaction. After this stage, the catalyst returns to its resting state (Figure ). Manganese exhibits different oxidation states in the intermediates formed during the catalytic cycle which gives rise to the possibility of multiple spin states for each intermediate. In this work, we modeled all the intermediates in all possible spin states to identify the ground spin state for each intermediate.