The coordination environment of inorganic compounds defines its chemical properties. Thus, synthesizing compounds with unusual geometries is appealing because of the possible new characteristics they may have, which may be important for applications varying from magnetism to catalysis. In particular, it is appealing to expand our knowledge of iron chemistry because of its low toxicity and cost relative to other transition metals. In 2011, Kl�fers described the first molecular square-planar high-spin Fe(II) compound, and since then only two other examples have been reported, all of which contain the metal center in a FeO42- environment. These findings revealed that such a geometry and electronic structure was possible even in the absence of macrocyclic ligands to enforce it and helped elucidate the requirements to favor this type of compound. Even though the synthesis of the first square-planar high-spin compounds represented a significant advancement, their reactivity remains unexplored, as well as the possibility of going beyond the FeO42- motif. Pincer ligands provide a convenient starting-point for expanding square-planar S = 2 Fe(II) centers beyond the homoleptic FeO42- unit. Pincer ligands can be modified easily to fine-tune the electronic and steric properties imparted to the metal center, thus opening up the possibility of selectively accessing the S = 1 and S = 2 states, which could have potential applications in spin-crossover materials. Pincer ligands have been used in numerous catalytic applications, and they have been expanded to include not only monoanionic variants but also trianionic analogues. In this work, we present the synthesis and characterization of the first trianionic pincer supported Fe(II) square planar complex in a S = 2 high spin state. Notable advances include the first high-field EPR characterization and expansion beyond an FeO42- core.

Square-planar high-spin Fe(II) center stabilized by a trianionic pincer-type ligand

248th National Meeting (2014)

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