SHORT INTRA-MOLECULAR HYDROGEN-BOND - CRYSTAL-STRUCTURE OF A TETRADENTATE ALPHA-AMINE OXIME COMPLEX OF PALLADIUM(II)

The crystal structure of [N,N'-(1, 3-propanediyl)bis(2-amino-2-methyl-3-butanone oximato)]palladium(II) nitrate, [Pd-(PnAO-H)](NO3), [Pd(C13H27N4O2)]NO3, has been determined from three-dimensional X-ray diffraction counter data. Unit cell dimensions are a = 11.0424 (5), b = 12.9114 (5), and c = 12.5871 (7) Å. The density of 1.65 g/cm3 calculated for four formula units per unit cell agrees with the flotation density of 1.66 g/cm3 The space group is P212121. A full-matrix least-squares refinement with 2838 independent reflections gave a final R(F2) value of 0.050. The structure consists of discrete, nearly square-planar palladium(II) complex cations and nitrate ions. A network of hydrogen bonding between amine nitrogens of the cation and oxygens of nitrate stabilizes the crystal structure. The steric requirements of the tetradentate PnAO are quite similar to two-coordinated bidentate AO ligands (C5H12N2O), and a propylene bridge does not impose any significant constraint on the coordination geometry. Similarly, the size of the metal ion in going from palladium(II) to platinum(II) does not change the molecular parameters because of lanthanide contraction in the case of platinum(II). The average Pd-N(amine) and Pd-N(oxime) distances are 2.040 (4) and 1.969 (4) Å, respectively. These distances are quite similar to the comparable distances in related platinum(II) complexes. The short intramolecular 0(l)⋯O(2) hydrogen bond (2.474 (5) Å) is apparently quite asymmetric and is equal to the corresponding bond in platinum(II) complexes, but significantly (0.05 Å) longer than that observed in the case of nickel(II) complexes. Other important average bond distances are N-O = 1.352 (5), C-N(oxime) = 1.278 (6), and C-N(amine) = 1.512 (6) Å. © 1979, American Chemical Society. All rights reserved.