We have investigated the physical properties of (n-CnH2n+1)(4)N [(FeFeIII)-Fe-II(dto)(3)](dto = C2O2S2) by means of Fe-57 Mossbauer spectroscopy, magnetic susceptibility, and ESR. From the analysis of Fe-57 Mossbauer spectra and ESR signal, we have discovered a new type of first order phase transition around 120 K for (n-CnH2n+1)(4)N (FeFeIII)-Fe-II(dto)(3)(n = 3, 4), where the charge transfer transition between Fe-II and Fe-III occurs reversibly. In the higher temperature phase, the Fe-III (S = 1/2) and Fell (S = 2) sites are coordinated by six S atoms and six 0 atoms, respectively. In the lower temperature phase, on the other hand, the Fe-III (S = 5/2) and Fe-II (S = 0) sites are coordinated by six 0 atoms and six S atoms, respectively. Moreover, we have found the ferromagnetic phase transition in this system. The ferromagnetic order is induced by the charge transfer interaction between the Fe-III (S = 5/2) and Fe-II (S = 0) sites.