Thermally Two-stepped Spin Transitions Induced by Intramolecular Electron Transfers in a Cyanide-bridged Molecular Square

A cyanide-bridged molecular square, [Co2Fe2(CN)(6)(tp*)(2)-(dtbbpy)(4)](PF6)(2)center dot 2MeOH (1) (tp* = hydrotris(3,5-dimethylpyrazol-1-yl) borate and dtbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine) was prepared by the reaction of (Bu4N)[Fe(CN)(3)(tp*)] with Co(CF3SO3)(2)center dot 6H(2)O and dtbbpy in methanol. Variable temperature X-ray structural analyses, magnetic and spectroscopic data revealed that 1 exhibited novel thermal two-stepped spin transitions induced by intramolecular electron transfers.