Palladium(0) and platinum(0) complexes of p,p′-diisopropyldibenzylideneacetone and their NMR spectra

The zerovalent diisopropyldibenzylideneacetone (dipdba, p-i-PrC₆H₄CHCHCOCHCH-p-i-PrC₆H₄) complexes M₂(dipdba)₃ (III, M = Pd; IV, M = Pt) have been prepared and their NMR spectra studied in solution. The ¹H and ¹³C NMR spectra of III and IV show complex patterns which are consistent with the complexes having very asymmetric structures in solution. The metal atoms are π-bonded to the olefins and the frameworks are stereochemically rigid over the temperature range ?90°C to +60°C on the NMR time scale. The ¹H spectra show the aryl groups to be rotating at +25°C but to be frozen out on the NMR time scale at low temperatures.