engleski

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

A series of novel complexes, dihalo-bis(N-benzyl-2-oxo-1-naphthylideneamine-O)zinc(II), ZnX2(bznapH)2 (1–3), dihalo-bis(N-p-tolyl-2-oxo-1-naphthylideneamine-O)zinc(II), ZnX2(tolnapH)2 (4–6), of the general formula [ZnX2(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 ZnI2(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 ZnX2(bznapH)2 vs. ZnX2(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.

Zinc complexes ; Schiff-bases ; Crystal structures ; IR ; UV and NMR spectroscopy ; Thermal analysis

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