Proton ENDOR spectroscopy of bis(2,2,6,6-tetramethylheptane-3,5-dionato)copper(II) and crystal structure of bis(2,2,6,6-tetramethylheptane-3,5-dionato)palladium(II)

Abstract

The proton electron nuclear double resonance spectroscopy of a single crystal of bis(2,2,6,6-tetramethylheptane-3,5-dionato)copper(II) in the palladium analogue has been studied. Tensors could be determined for the γ-proton and two nearest Bu^t protons as well as six protons on the nearest-neighbour palladium complex. The assignment of most of these was enabled by the comparison with theoretically calculated tensors. This calculation procedure has been described previously: it uses the molecular orbital coefficients as obtained from an extended Huckel calculation and includes all two- and three-centre contributions. The remaining experimental curves could not be fitted to calculated tensors. The structure of the palladium analogue, C₂₂H₃₈O₄Pd, was determined by X-ray crystallography at 140 K: monoclinic, space group P2₁/n, a= 11.245(3), b= 12.008(8), c= 9.851(3)Å, β= 110.17(3)°, and Z= 2 (Mo-K_α radiation, graphite crystal monochromator). Final conventional R= 0.029, R′= 0.044 for 1 654 unique reflections and 186 variables.