Two new heteroleptic complexes [Fe(1bppCOOH)(3bpp-bph)](ClO 4 ) 2 •solv (1•solv, solv = various solvents; 1bppCOOH = 2,6-bis(1H-pyrazol-1-yl)isonicotinic acid; 3bpp-bph = 2,6-bis(5-([1,1'-biphenyl]-4-yl)-1H-pyrazol-3-yl)pyridine) and [Fe(1bppCOOH)(1bppCOOEt)](ClO 4 ) 2 •0.5Me 2 CO (2•0.5Me 2 CO, 1bppCOOEt = ethyl 2,6bis(1H-pyrazol-1-yl)isonicotinate) have been designed and prepared. The heteroleptic compound 1•solv was obtained by the combination of stoichiometric amounts of Fe(ClO 4 ) 2 , 1bppCOOH and 3bpp-bph, and it was designed to fine tune the spin crossover (SCO) properties with respect to the previously reported homoleptic compound [Fe(1bppCOOH) 2 ](ClO 4 ) 2 . Indeed, the introduction of a new substituted 3bpp ligand induces a weaker ligand field in addition to promoting the formation of π•••π and C−H•••π intermolecular interactions through the biphenyl groups. For the desolvated counterpart 1, this results into a shift of the SCO curve towards room temperature and the observation of a 13 K hysteresis width. Besides, compound 2•0.5Me 2 CO, which represents the first example of a heteroleptic complex containing two 1bpp tridentate ligands, stabilizes the LS state at room temperature confirming the same trend observed for the corresponding homoleptic compounds. Interestingly, both 1 and 2•0.5Me 2 CO heteroleptic complexes exhibit photo-switchable properties when irradiating with a 523 nm laser at 10 K. Preliminary characterization of the deposited complexes on native SiO 2 by X-Ray Absorption (XAS) measurements suggests oxidation and decomposition of the complexes.