Electron transfer reactions involving trans- and fluorinated benzonitriles

Article abstract of DOI:10.1016/0022-328X(92)83474-V

The complex trans- reacts with activated benzonitriles such as 4-R-C6F4CN (R=F, H, CN, OCH3) bearing electron-withdrawing substituents to give the new platinum(II) aryl complexes trans-(PCy3)2>, which have been isolated and fully characterized, and a hydridofluoride trans-, where F is either F or HF2, which has been detected in solution.These complexes and related by-products from the reaction have been characterized by one- and two-dimensional multinuclear NMR spectroscopy.A reaction mechanism involving rate-determining electron transfer from the dihydride complex to the organic substrate is postulated on the basis of (i) the relative reaction rates for the nitriles (p-C6F4(CN)2 > C6F5CN > p-C6HF4CN > p-C6F4(OCH3)CN > o,o-C6H3F2CN), which parallel their electron affinities, and (ii) the observation of a radical by ESR spectroscopy after spin-trapping with PBN.