Dyke John M, Emsley James W, Greenacre Victoria K, Levason William, Monzittu Francesco M, Reid Gillian, De Luca Giuseppina
School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K.
Department of Chemistry and Chemical Technologies, University of Calabria, Arcavacata di Rende 87036, Italy.
Inorg Chem. 2020 Apr 6;59(7):4517-4526. doi: 10.1021/acs.inorgchem.9b03630. Epub 2020 Mar 18.
The reaction of PMe or PPh with PF in anhydrous CHCl or hexane forms the white, moisture-sensitive complexes [PF(PR)] (R = Me, Ph). Similar reactions involving the diphosphines -CH(PR) afford the complexes [PF{-CH(PR)}][PF]. The X-ray structures of [PF(PR)] and [PF{-CH(PMe)}][PF] show pseudo-octahedral fluorophosphorus centers. Multinuclear NMR spectra (H, F{H}, P{H}) show that in solution in CHCl/CDCl the structures determined crystallographically are the only species present for [PF(PMe)] and [PF{-CH(PMe)}][PF] but that [PF(PPh)] and [PF{-CH(PPh)}][PF] exhibit reversible dissociation of the phosphine at ambient temperatures, although exchange slows at low temperatures. The complex F{H} and P{H} NMR spectra have been analyzed, including those of the cation [PF{-CH(PMe)}], which is a second-order AA'XX'BM spin system. The unstable [PF(AsMe)], which decomposes in a few hours at ambient temperatures, has also been isolated and spectroscopically characterized; neither AsPh nor SbEt forms similar complexes. The electronic structures of the PF complexes have been explored by DFT calculations. The DFT optimized geometries for [PF(PMe)], [PF(PPh)], and [PF{-CH(PMe)}] are in good agreement with their respective crystal structure geometries. DFT calculations on the PF-L complexes reveal the P-L bond strength falls with L in the order PMe > PPh > AsMe, consistent with the experimentally observed stabilities, and in the PF-L complexes, electron transfer from L to PF on forming these complexes also follows the order PMe > PPh ≈ AsMe.
