Dynamic and static Jahn-Teller distortions in a CuN₆ cage complex

EPR studies of pure and doped (in an isostructural diamagnetic zinc lattice) polycrystalline [Cu(di(amH)sar)](NO3)4 over a wide range of temperature (7–280 K) show that both undergo a transition from dynamic to static Jahn-Teller distortions. The spectra were simulated to get the g- and A-tensors. The transition temperature for the pure polycrystalline sample is ⩽120 K and for the doped one it is above room temperature. There is evidence for the existence of cooperative and localized Jahn-Teller distortions respectively in pure and doped crystals. From the g-tensors of the pure polycrystalline sample there is evidence, supported by single-crystal results, of rapid electronic exchange between two inequivalent Cu(II) sites