Double exchange in a mixed-valent octanuclear iron cluster, [Fe8(μ4-O)4(μ-4-Cl-pz)12Cl4](-). by Zueva, E, Herchel, R, Borshch, SA, Govor, E, Sameera, WM, McDonald, R, Singleton, J, Krzystek, J, Trávníček, Z, Sanakis, Y, McGrady, J, Raptis, R