Packing of complexes and intermolecular interactions in the crystals of volatile palladium(II) beta-diketonates, crystal structure of palladium(II) benzoyltrifluoroacetonate

This paper reports on the synthesis and crystal structure analysis of palladium(il) bis-(trans-benzylfluoroacetonate). Crystal data for PdO4C20F6H12 : a = 4.748, b = 22.237, c = 9.410 Angstrom, beta = 105.44 degrees, Z = 2, space group P2(1)/c, d(cale) = 1.86 g/cm(3). CAD-4 diffractometer (MoKalpha), heavy atom method, R = 0.041 for 986 reflections. The structure is molecular; the planar molecules are stacked. The Pd atom is surrounded by a structure of four O atoms (Pd-O = 1.97 Angstrom, chelate angle 94.4 degrees): Pd is involved in additional interactions rr with the Cy atoms of two neighboring molecules (Pd...C gamma congruent to 3.44 Angstrom). The molecular structure of palladium beta-diketonate complexes, molecular packing in crystal, and intermolecular interactions are considered. The van der Waals energies of the crystal lattice are calculated. The results are compared with the experimental values. In the structures of palladium(ll) beta-diketonates, three groups of crystals are isolated: one group with 2 nearest-neighbor interactions (stacks), the second with 4 nearest-neighbor interactions (two-dimensional nets), and the third with nearest-neighbor interaction (dimers). The latter are characteristic of the cis-complexes. The interactions with 10-12 nearest neighbor molecules determine the energetics of the whole crystal. The high volatility of Pd(hfa)(2) is explained by the weaker intermolecular contacts between stacks in crystal.