Ligand substitution effects on the charge transport properties of the spin crossover complex [Fe(Htrz) (trz) (NHtrz) ](BF)y·nHO.

The complex dielectric permittivity of a series of spin crossover complexes, with variable ligand stoichiometry [Fe(Htrz) (trz) (NHtrz) ](BF) ·nHO, has been investigated as a function of temperature in a wide frequency range. In each compound, a substantial drop of the conductivity and permittivity is evidenced when going from the low spin to the high spin state, albeit with decreasing amplitude for increasing ligand substitution (i.e.

Broad-Band Dielectric Spectroscopy Reveals Peak Values of Conductivity and Permittivity Switching upon Spin Crossover.

We use broad-band dielectric spectroscopy to investigate the spin-state dependence of electrical properties of the [Fe(Htrz)(trz)](BF) spin crossover complex. We show that the Havriliak-Negami theory can fully describe the variation of the complex dielectric permittivity of the material across the pressure-temperature phase diagram. The analysis reveals three dielectric relaxation processes, which we attribute to electrode/interface polarization, dipole relaxation, and charge transport relaxation.