Two Discoveries in One Crystal: -Type Oxime Radical as an Unforeseen Building Block in Molecular Magnetics and Its Spatial Structure

Inthe present work, the study of the unusual interaction betweencopper hexafluoroacetylacetonate and the diacetyliminoxyl radicalresulted in two discoveries from different fields: the determinationof the oxime radical spatial structure and the introduction of anoxime radical into the field of molecular magnetic material design.Oxime radicals are key plausible intermediates in the processes ofoxidative CH-functionalization and in the synthesis of functionalizedisoxazolines from oximes. Due to the lack of X-ray diffraction datafor oxime radicals, the knowledge about their structure is based mainlyon indirect approaches, spectroscopic methods (electron paramagneticresonance and IR), and quantum chemical calculations. The structureof the oxime radical was determined for the first time by stabilizingthe diacetyliminoxyl radical in the form of its complex with copper(II) hexafluoroacetylacetonate (Cu(hfac)(2)), followed bysingle-crystal X-ray diffraction analysis. Although oxime radicalsare known to undergo oxidative coupling with acetylacetonate ligandsin transition-metal complexes, a complex is formed with intact hfacligands. X-ray diffraction studies have shown that the oxime radicalis coordinated with copper ions through the oxygen atoms of the carbonylgroups without the direct involvement of the C UN-O-& BULL; radical moiety. The structure of the coordinated diacetyliminoxylis in good agreement with the density functional theory (DFT) predictionfor free diacetyliminoxyl due to the very weak interaction of theradical molecule with copper ions. Remarkably, both weak ferromagneticand antiferromagnetic interactions between Cu (II) and oxime radicalshave been revealed by modeling the temperature dependence of magneticsusceptibility and confirmed by DFT calculations, rendering diacetyliminoxyla promising building block for the design of molecular magnets. Oxime radical was identified as unexpectednew type of buildingblock for molecular magnetic synthesis with record spin content peratom count. First X-ray data for the oxime radical was achieved.