SYNTHESIS AND REACTIONS OF CYCLOPALLADATED COMPOUNDS DERIVED FROM N,N'-DIALKYLBENZENE-1,3-DICARBALDIMINES [ALKYL = ETHYL (H2L1), BUTYL OR OCTYL] AND N,N'-DIBENZYL-BENZENE-1,3-DICARBALDIMINE - CRYSTAL-STRUCTURE OF [PD2L1(PY)4][CLO4]2 (PY = PYRIDINE)

The reactions of N,N'-dialkylbenzene-1,3-dicarbaldimines (alkyl = Et, H2L1; Bu, H2L2 or C8H17, H2L3) and N,N'-dibenzylbenzene-1,3-dicarbaldimine (H2L4) with Pd(O2CMe)2 have been studied. In all cases tetra-mu-acetato cyclopalladated compounds, [Pd4L2(O2CMe)4], were obtained in which metallation had occurred at the 4,6 positions of the benzene ring. The mu-chloro analgoues, [Pd4L2Cl4], can be obtained either by reaction of the Schiff bases with Li2[PdCl4] or by metathesis of the acetato complexes. Bridge-splitting reactions of [Pd4L2Cl4] with pyridine(py), 4-methylpyridine, pyrazole, 3,5-dimethylpyrazole, amines, and a number of monoprotic bidentate chelating ligands, viz. acetylacetone, dibenzoylmethane and its monothio analogue, ethylacetoacetate, salicylaldehyde, N-methylsalicylideneimine and sodium N,N-dipropyldithiocarbamate have also been investigated. The products have been characterized by H-1 and C-13 NMR spectroscopy. The X-ray crystal structure of [Pd2L1(py)4][ClO4]2 has been determined which crystallizes in the triclinic space group P1BAR with a = 10.889(1), b = 16.981(2), c = 10.227(1) angstrom, alpha = 92.99(1), beta = 93.14(1), gamma = 73.65(1)-degrees and Z = 2; refinement led to R = 0.059 and R' = 0.062 using 3620 unique reflections with I > 3-sigma(I).