Complexes of zinc(II) halides with N-benzyl- and N- p-tolyl-2-oxo-1-naphthylideneamine – preparation and characterization

Abstract

A series of novel complexes, dihalo-bis( N-benzyl-2-oxo-1-naphthylideneamine- O)zinc(II), ZnX 2(bznapH) 2 ( 1– 3), dihalo-bis( N- p-tolyl-2-oxo-1-naphthylideneamine- O)zinc(II), ZnX 2(tolnapH) 2 ( 4– 6), of the general formula [ZnX 2(LH) 2] X=Cl, Br, I, have been prepared. The crystal structures of four compounds ( 1– 4) reveal four coordinated zinc centres by two halogen and two oxygen atoms from the Schiff-base in the form of distorted tetrahedra. Complex 4 crystallizes as the one-to-one solvate with ethanol. The tetrahedral distortion is most pronounced in the structure of ZnI 2(bznapH) 2 complex. X-ray structural data showed that the Schiff-base ligand in the naphthylideneamine tautomeric form is weakly bound to Zn atom in 1– 4 (being in the range from 1.952(3) Å in 2 to 2.002(3) Å in 4). The molecular structures of 1– 4 are governed by the type of halide and the corresponding Schiff-base. Although the structure comparison of ZnX 2(bznapH) 2 vs. ZnX 2(tolnapH) 2 leads to the conclusion that ligand spatial accomodation (non-planar bznapH with aliphatic interruption vs. aromatic tolnapH) is the dominating factor in the crystal structures. The crystal structures of 2– 4 are dominated by van der Waals forces. There is a weak intermolecular hydrogen bond of the C–H⋯Cl type in 1 (3.710(5) Å joining molecules into endless chains. The UV–Vis and 1H NMR spectra, obtained in ethanolic and acetone solution indicate that the complexes do not exist in the solutions.