Direct observation of an equilibrium between two anion-cation orientations in olefin Pt(ii) complex ion pairs by HOESY NMR spectroscopyElectronic supplementary information (ESI) available: details of the experimental measurements and calculations, along with the NMR intramolecular characterization of complexes 1–3. See http://www.rsc.org/suppdata/nj/b2/b212088g/