We have investigated the spin-crossover behavior for one-dimensional complexes [Fe(trz)(3)](RSO3)(2)(trz= triazole) and two-dimensional mixed-valence complexes (CnH2n+1)(4)N[(FeFeIII)-Fe-II(dto)(3)] (dto= C2O2S2). For the case of [Fe(4-NH(2)trz)(3)](RSO3)(2), we have controlled Tc and the thermal hysteresis width of spin transition by using the isomerization of counter anion or the fastener effect between the alkyl chains of counter anions CnH2n+1SO3-. Moreover, we have synthesized a [Fe(Htrz)(3)] film by using an ion-exchange film having SO3-, which shows the spin transition around room temperature. For the case of (CnH2n+1)(4)N[(FeFeIII)-Fe-II(dto)(3)](n = 3,4), we have found a charge transfer phase transition between Fe-II and Fe-III around 120 K.