Mechanistic Aspects of the Photofunctionalisation of Tetraalkylammonium Cations by [PtCl6]2−

Unexpected activation of the tetrabutylammonium cation in the presence of hexachloroplatinate(IV) under light to give a dinuclear complex of trans-μ2:η2,η2-1,3-butadiene-bis(trichloroplatinate(II)) along with a proposed mechanism of the activation has been reported. The mechanism has been investigated using a combination of photodissociation photodetachment mass spectrometry, and frozen-matrix EPR spectroscopy, in addition to 1D and 2D NMR spectroscopy. In addition to the Bu4N+ salts of [PtCl6]2− that were part of the original observations, the reactivity of Bu4P+, Pr4N+, and Pe4N+ (Pe = pentyl) salts has also been investigated, and, in addition, the possible involvement of η2-butene complex intermediates has been investigated. The combined results provide additional evidence and support for the originally proposed mechanism of activation of the Bu4N+ cation.