In the field of synthetic nonheme oxoiron(IV) chemistry the crystallographic characterization of the [FeIV(O)(TMC)(MeCN)]2+ (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) complex by Que and co-workers in 2003 opened up the gates for what could be judged as a flood of related compounds. Despite the large number of complexes reported belonging to the family of oxoiron(IV) complexes, some aspects of their chemistry remain nebulous. In the presentation we report the chemistry of the [FeIV(O)(TMC)(H2O)]2+ complex (Figure 1) in water and the identification of a conjugate acid-base pair. In particular, we have determined the pKa of the H2O ligand bound in the trans position with respect to the oxo unit as a means of assessing the Lewis acidity of an oxoiron(IV) unit in aqueous media. Furthermore, the bonding in the oxoiron(IV) unit will be discussed, as well as how it is reflected by the determined pKa value. The last part of the talk will focus on the role of isomers in the conjugate base [FeIV(O)(TMC)(OH)]+ complex and how it is connected to the role of trace water when studying TMC-based complexes in non-aqueous solvents.

Can FeIV(O)’s swim? The aqueous chemistry of the [FeIV(O)(TMC)]2+ complex

253rd National Meeting (2017)

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