Fig. 2. ¹H VT NMR spectra in methanol-d ₄ of H₃CP256 (bottom) and [Zr(CP256)]⁺ demonstrating high fluxionality of the complex. Intensity of signal >5.5 ppm is magnified (×8) relative to region <5.5 ppm. ¹H protons of acetylacetonate ligand have exchanged with deuterons.