Synthesis and X-ray diffraction study of Zn(II) complexes with o-phthalic acid and aromatic amines

New zinc (II) complexes [Zn(Pht)A(2)], where Pht(2) = dianion of o-phthalic acid. A = pyridine (1), 3-methylpyridine (2). 4-methylpyridine (3) and [Zn(Pht)A] (A = 4-methylpyridine (4)) have been synthesised and characterised by X-ray crystallography. The compounds have polymeric structures due to 1,6-bridging ability of the o-phthalate ligand. Polymeric chains exhibit three types of organisation in the crystal. Complexes 1 and 2 have similar structures. where Zn atom is coordinated by two oxygen atoms of two carboxylate groups and two nitrogen atoms of N-containing ligands. Two independent Zn atoms in 3 have different environments: tetrahedral N2O2 and distorted square-pyramidal N2O3. One of the acid residues behaves as bidentate 1,6-bridge, while the other acts as tridentate (1.6-bridging and 1,3-chelating) ligand. One of the Zn atoms in 4 has a tetrahedral NO, geometry, while the second is characterised by a distorted octahedral NO5 coordination polyhedron. Both phthalate anions are tetradentate and act as syn-syn, syn-anti and monoatomic Zn-O-Zn bridging ligands. The IR spectra are discussed in relation to the crystal structures. (C) 2001 Elsevier Science Ltd. All rights reserved.