We describe the first example of a bis-tridentate heteroleptic iron(III) spin crossover (SCO) complex, [Fe(3-OMe-SalEen)(thsa)]. Compared to the parent homoleptic compounds, the spin crossover features in the heteroleptic species are enhanced with a gradual–abrupt spin transition at 344 K. Clear correlations between π–π interactions and the T_1/2 value have been revealed.