Nuclear Magnetic Resonance and Computational Study of trans-(μ₂:η²,η²-1,3-Butadiene)bis(trichloroplatinate(II))

Abstract

The complex bis­(tetrabutylammonium) (trans-μ2:η2,η2-1,3-butadiene)­bis­(trichloroplatinate­(II)), identified from its X-ray single-crystal structure, is formed when tetrabutylammonium hexachloroplatinate­(IV) is irradiated in solution. In principle, the complex can exist in one of four conformers (combining cis and trans isomers of the butadiene and syn and anti arrangements of the two PtCl3 – moieties) and DFT calculations suggest that three of these ought to be stable in solution in CDCl3. However, dissolving the anti,trans conformer (identified from both crystallography and 13C­{1H} MAS NMR spectroscopy) in solution leads to the formation of a second conformer, identified by a combination of NMR experiments, in amounts that depend on the solvent used. Then, on standing in solution, a third species forms that contains a single PtCl3 – moiety. The identification and interconversion of these various species are discussed.