Room-Temperature Defluorination of PTFE and SF6 by Magnesium(0), Magnesium(I), and Magnesium-Dinitrogen Compounds

<jats:p> The room temperature reductive defluorination/degradation of the PFAS “forever chemical” PTFE, and the extremely potent greenhouse gas SF <jats:sub>6</jats:sub> , has been achieved by their treatment with either the magnesium(0) [{( <jats:sup>tBu</jats:sup> BDI <jats:sup>TCHP</jats:sup> )MgNa} <jats:sub>2</jats:sub> ] ( <jats:sup>tBu</jats:sup> BDI <jats:sup>TCHP</jats:sup> = [{(TCHP)NC(tBu)} <jats:sub>2</jats:sub> CH] <jats:sup>-</jats:sup> , TCHP = 2,4,6-tricyclohexylphenyl), magnesium-dinitrogen [K <jats:sub>2</jats:sub> {( <jats:sup>Et</jats:sup> NON <jats:sup>TCHP</jats:sup> )Mg} <jats:sub>2</jats:sub> (m-N <jats:sub>2</jats:sub> )] ( <jats:sup>Et</jats:sup> NON <jats:sup>TCHP</jats:sup> = 4,5-bis{(TCHP)N}-2,7-diethyl-9,9-dimethylxanthene) or anionic dimagnesium(I)  [K <jats:sub>2</jats:sub> {( <jats:sup>tBu</jats:sup> NON <jats:sup>Trip</jats:sup> )Mg} <jats:sub>2</jats:sub> ] ( <jats:sup>tBu</jats:sup> NON <jats:sup>Trip</jats:sup> = 4,5-bis{(Trip)N}-2,7-di- <jats:italic toggle="yes">tert</jats:italic> -butyl-9,9-dimethylxanthene, Trip = 2,4,6-triisopropylphenyl) compounds. In all cases, facile E‒F (E = C or S) bond activations occurred, leading to the formation of dimeric, anionic magnesium(II) fluoride products, [{( <jats:sup>tBu</jats:sup> BDI <jats:sup>TCHP</jats:sup> )MgF <jats:sub>2</jats:sub> } <jats:sub>2</jats:sub> (m-Na) <jats:sub>2</jats:sub> ], [{( <jats:sup>Et</jats:sup> NON <jats:sup>TCHP</jats:sup> )MgF} <jats:sub>2</jats:sub> (m-K) <jats:sub>2</jats:sub> ] and [{( <jats:sup>tBu</jats:sup> NON <jats:sup>Trip</jats:sup> )MgF} <jats:sub>2</jats:sub> (m-K) <jats:sub>2</jats:sub> ], respectively. Treatment of two of these with 18-crown-6 led to their de-aggregation, and formation of monomeric magnesium(II) fluorides, <jats:italic toggle="yes">viz.</jats:italic> [( <jats:sup>tBu</jats:sup> BDI <jats:sup>TCHP</jats:sup> )Mg(m-F) <jats:sub>2</jats:sub> Na(k <jats:sup>2</jats:sup> -18-crown-6)] and [( <jats:sup>tBu</jats:sup> NON <jats:sup>Trip</jats:sup> )MgFK(k <jats:sup>6</jats:sup> -18-crown-6)]. Analyses of the dark grey, insoluble products resulting from the reductions of PTFE ( <jats:italic toggle="yes">viz.</jats:italic> PTFE-R) by FTIR spectroscopy, imply they can be formulated as (F <jats:sub>2</jats:sub> C‒CF <jats:sub>2</jats:sub> ) <jats:sub>x</jats:sub> (FC=CF) <jats:sub>y</jats:sub> . The outcome of the sulfur component of SF <jats:sub>6</jats:sub> in its reduction reactions could not be determined. This study highlights the utility that low oxidation state magnesium compounds have for the facile degradation of normally inert PFAS, and related fluorinated, chemicals. </jats:p>