A highly distorted high spin Fe(ii)-complex, [Fe(1-BPP-COOC2H5)2](ClO4)2·CH3CN, with a trans-N(pyridine)-Fe-N(pyridine) angle (φ) of 158.83(17)° showed lattice solvent dependent bi-stable spin-state switching characteristics with T1/2 = ca. 233 K and a high thermal hysteresis width (ΔT) of 101 K, for the first cooling and heating cycle, unprecedented for the [Fe(BPP)2]2+ series of complexes; the results presented in this study are fundamentally important and have implications towards the realization of device architectures based on bi-stable SCO complexes.