Synthesis and reactions of cyclopalladated compounds derived from N,N'-dialkylbenzene-1,3-dicarbaldimines [alkyl = ethyl (H₂L¹), butyl or octyl] and N,N'-dibenzylbenzene-1,3-dicarbaldimine. Crystal structure of [Pd₂L¹(py)₄][ClO₄]₂(py = pyridine)

Abstract

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-µ-acetato cyclopalladated compounds, [Pd₄L²(O₂CMe)₄], were obtained in which metallation had occurred at the 4,6 positions of the benzene ring. The µ-chloro analogues, [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-methylsalicyiideneimine and sodium N,N'-dipropyldithiocarbamate have also been investigated. The products have been characterized by ¹H ¹³C NMR spectroscopy. The X-ray crystal structure of [Pd₂L¹(py)₄][ClO₄]₂ has been determined which crystallizes in the triclinic space group P with a= 10.889(1), b= 16.981(2), c= 10.227(1Å, α= 92.99(1), β= 93.14(1), γ= 73.65(1)° and Z= 2; refinement led to R= 0.059 and R'= 0.062 using 3620 unique reflections with I ≥3σ(I).