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Ammonium pertechnetate reacts in mixtures of trifluoromethanesulfonic anhydride and trifluoromethanesulfonic acid under final formation of ammonium pentakis(trifluoromethanesulfonato)oxidotechnetate(V), (NH 4 ) 2 [TcO(OTf) 5 ]. The reaction proceeds only at exact concentrations and under the exclusion of air and moisture via pertechnetyl trifluoromethanesulfonate, [TcO 3 (OTf)], and intermediate Tc VI species. 99 Tc nuclear magnetic resonance (NMR) has been used to study the Tc VII compound and electron paramagnetic resonance (EPR), 99 Tc NMR and X-ray absorption near-edge structure (XANES) experiments indicate the presence of the reduced technetium species. In moist air, (NH 4 ) 2 [TcO(OTf) 5 ] slowly hydrolyses under formation of the tetrameric oxidotechnetate(V) (NH 4 ) 4 [{TcO(TcO 4 ) 4 } 4 ] ⋅10 H 2 O. Single-crystal X-ray crystallography was used to determine the solid-state structures. Additionally, UV/Vis absorption and IR spectra as well as quantum chemical calculations confirm the identity of the species., (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Combination of three radical anionic Ph-BIAN ligands (Ph-BIAN=bis-(phenylimino)-acenaphthenequinone) with lanthanoid ions leads to a series of homoleptic, six-coordinate complexes of the type Ln(Ph-BIAN) 3 . Magnetic coupling data were measured by paramagnetic solution NMR spectroscopy. Combining 1 H NMR with 2 H NMR of partially deuterated compounds allowed a detailed study of the magnetic susceptibility anisotropies over a large temperature range. The observed chemical shifts were separated into ligand- and metal-centered contributions by comparison with the Y analogue (diamagnetic at the metal). The metal-centered contributions of the complexes with the paramagnetic ions could then be separated into pseudocontact and Fermi contact shifts. The latter is large within the Ph-BIAN scaffold, which shows that magnetic coupling is significant between the lanthanide ion and the radical ligand. Pseudocontact shifts were further correlated to structural data obtained from X-ray diffraction experiments. Ligand-field parameters were determined by fitting the temperature dependence of the observed magnetic susceptibility anisotropies. The electronic structure determined by this approach shows, that the Er and Tm analogues are candidates for single molecule magnets (SMM). These results demonstrate the possibilities for the application of NMR spectroscopy in investigations of paramagnetic systems in general and single molecule magnets in particular., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)