Synthesis and characterization ofSchiffbases derived from 1:1 and 1:2 condensations of benzoylacetylacetone with N-benzylethylenediamine. Complexes with some divalent metal ions

摘要

The synthesis and characterization of two new ligands derived from the 1:1 and 1:2Schiffbase condensation of benzoylacetylacetone with N-benzylethylenediamine as well as some of their metal complexes are reported. The 1:1Schiffbase1is a potential tetradentate, binucleating ligand with two adjacent coordination sites NNO(X) (X=Cl, NO3) and OO(XY), whereXandYare exogenic donor atoms. The reaction of1with PdCl42−affords a mononuclear, square-planar complex3awith the metal atom coordinated to the NNO site of1and to Cl−. The X-ray structure of this complex shows that the coordination of the Pd atom by an NNO (Cl) moiety reduces the available space in OO(XY) site for coordinating another metal atom; moreover, the small distance between the two oxygen atoms of the “hard base” site OO(XY) suggests the presence of hydrogen bonding and therefore this proton is not easily displaced by a typical soft acid such as Pd2+. When the same ligand reacts with Ni(II) or Cu(II) nitrates, again only mononuclear complexes3band3care obtained with the same donor atoms as for the Pd(II) complex but withX=NO3. The 1:2Schiffbase4, a potentially binucleating ligand with two non-equivalent coordination sites NNO(X), was not isolated as a free ligand. However, it gave the binuclear Hg(II) complex5by the reaction of benzoylacetylacetone and N-benzylethylenediamine in the presence o