Using an inappropriate spin state from one of these sources forces the reaction pathway through an excited state with an associated energetic penalty. Furthermore, the 3d transition metal porphyrins under study are known to contain low-lying excited states associated with both unoccupied metal and porphyrin orbitals, which make the proper determination of ground states challenging for DFT. Complicating the matter, different functionals tend to favor different spin states, albeit in a somewhat predictable way. In particular, including exact exchange in a functional preferentially stabilizes high-spin states in direct proportion to the percentage of exchange included. f Splitting energy relative to quartet is less than 1 kcal/mol. Table shows the ground state multiplicities that we determined by DFT and DLPNO-CCSD(T) alongside those given by experiments and higher level calculations when available. At first glance, the DFT multiplicities, which were determined by taking the mode of the multiplicities predicted by all functionals, show excellent agreement with DLPNO-CCSD(T) and experimental results.