Spectroscopy and DFT calculations using B3LYP/ZORA-def2-TZVP were further employed to reveal the electronic structure of 4. The EPR spectrum of 4 in 2methyltetrahydrofuran (MeTHF) at 77 K was modeled as an S = 1/2 spin system with g = [2.200, 2.120, 1.998] and coupling to three 31 P nuclei: two with |A| = [71, 83, 71] MHz and one with |A| = [0, 37, 37] MHz (Figure ). Mulliken spin population analysis showed spin populations of -0.036 on the axial phosphorus atoms and -0.019 on the equatorial phosphorus, in agreement with the fit to two equivalent 31 P nuclei having larger A than a third 31 P nucleus. The spin population analysis also showed an averaged spin density of 0.031 on the two ligand nitrogen atoms, though the smaller nuclear magnetic moment of N relative to P likely contributed to smaller, unresolvable N hyperfine splitting, which was modeled by anisotropic H-strain of [66, 27, 0] MHz in the simulation.