EPR of hexakis(1-propyltetrazole)copper(II) tetrafluoroborate and Cu(II)-doped hexakis(1-propyltetrazole)zinc(II) tetrafluoroborate. Dynamic to static Jahn–Teller distortion

EPR studies have been carried out on Cu(ptz)6(BF4)2 and Cu(II)-doped Zn(ptz)6(BF4)2 in single crystal and powder forms. Powder spectra, measured as a function of temperature over a wide range (6–300 K), are explicable in terms of a transition from dynamic to static Jahn–Teller distortion. Angular variation at 77 K has been carried out for single crystals of both diluted and undiluted samples and successfully simulated to match the experimental spectra. Angular variation studies are consistent with the tetragonally elongated geometry, with dx2−y2 ground state, typically found for the static Jahn–Teller effect in CuL62+ systems.