Functionalization of surfaces with spin crossover complexes is an intensively studied topic. Starting from dinuclear iron(III)-salten complexes [Fe(salten)-(pyS)]2(BPh4)2 and [Fe(thiotolylsalten)(NCS)]2 with disulfide-containing bridging ligands, the corresponding mononuclear complexes [Fe(salten)(pyS)]+ and [Fe(thiotolylsalten)-(NCS)] were covalently attached to Au(111) surfaces and analyzed with Infrared reflection absorption spectroscopy (IRRAS). In comparison with the bulk material data of the [Fe(salten)pyS]+ complexes , the surface vibrational spectra show an anomaly regarding the geometry of adsorbed complexes. The salten-ligand is partially decoordinated from the Fe(III)center and one of its phenolate arms binds to the Au(111) surface. To find a system, which retains the geometry on the surface, [Fe(thiotolylsalten)NCS] monolayers were prepared and also investigated on the surface. Here no anomaly was observed, which indicates that the coordination sphere of the complex in the bulk is retained on the surface. The implications of these results with respect to the preparation of surface-adsorbed monolayers of functional transition-metal complexes are discussed.