ELECTRON-TRANSFER REACTIONS INVOLVING TRANS-[PTH2(PCY3)2] AND FLUORINATED BENZONITRILES

The complex trans-[PtH2(PCy3)2] 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-[PtH{RC6F3CN}(PCy3)2], which have been isolated and fully characterized, and a hydridofluoride trans-[PtH("F")(PCy3)2], 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.