A scan of the potential energy surface (PES) was then performed by displacing the geometry along the harmonic normal mode (Q i ) prior to mass weighting in Cartesian increments of 0.25 for Cr 2 (mhp) 4 and and Cr 2 (dmp) 4 . Single point CASPT2 calculations are performed using the same level of theory previously described. Coordinates are provided as supporting information for each displacement. Since there is literature precedent that the Cr-Cr bond distance is affected by the choice of zeroth-order Hamiltonian, analogous CASPT2 calculations were performed along the normal mode using the OpenMolcas program package. An imaginary shift of 0.2 a.u. and the so-called IPEA shift of 0.25 was employed. ANO-RCC basis sets were used (see caption of DFT geometry optimizations and harmonic vibrational frequencies were computed as implemented in the Turbomole program package. The M06 functional was used with the def2-TZVP basis set. Singlet and triplet spin states were considered. Attempts to optimize the geometry with a broken-symmetry singlet routinely relax to the closed-shell singlet.