Crystal and molecular structure of bis[(1,2-dihapto-3,5-dimethyl-pyrazolido)-π-allylpalladium(II)]

The crystal and molecular structure of bis[(1,2-dihapto-3,5-dimethylpyrazolido)--allylpalladium(II)], C₁₆H₂₄N₄Pd₂, has been determined by X-ray diffraction techniques. The crystals are monoclinic,P2₁/c (No. 14), witha = 8.752(1),b = 18.932(2),c = 11.780(3) Å, and = 109.78(1) °. The observed crystal density (1.746 g cm^–3) agrees well with that calculated on the basis of four molecules per unit cell (1.754 g cm^–3). The structure has been refined by full-matrix least-squares techniques to a finalR₁ value of 0.045 (R₂ = 0.056) for 2974 unique reflections withI_net7 counts sec^–1. The Pd₂N₄ ring is in a boat conformation in which the two palladium atoms are 1.113 and 1.064 Å out of the plane defined by the four nitrogen atoms. The Pd-C bond distances to the terminal atoms of the -allyl groups (2.12 Å) are longer than those to the central carbon atoms (2.06 Å). The molecule possesses approximatemm2 (C_2v) symmetry.