Fig. 1. Top, Mössbauer spectrum recorded at 80 K in zero-field of 1^(IV) NTs (left) in acetonitrile and 2^(IV) NTs (right) prepared in acetone. Experimental data are hatched bars and solid lines represent the contributions of 1^(IV) NTs and 2^(IV) NTs. Centre, UV-vis spectrum of oxidation of 1^(II) to 1^(IV) NTs in CH₃CN; kinetic trace shows the evolution of the λ_max = 750 nm feature. Below, HR-MS spectrum of 1^(IV) NTs prepared in CH₃CN exhibiting a base peak at m/z 275.09; inset show amplification of major peak for [Fe^IV(NTs)(MePy₂tacn)]²⁺ species. Proper simulation of the peak requires inclusion of ≈10% of [Fe^III(NHTs)(MePy₂tacn)]²⁺ in the isotopic pattern corresponding to [Fe^IV(NTs)(MePy₂tacn)]²⁺.