Synthesis and characterization of a nickel(II) complex of 9-methoxy-2,3-dihydro-1,4-benzoxyzepine derived from a Schiff base ligand and its ligand substitution reaction

A Schiff base ligand (2-{(E)-[2-bromoethyl)imino]methyl}-6-methoxy phenol (LH) has been synthesized and characterized by NMR, IR spectroscopy and elemental analysis. The reaction of LH with nickel acetate tetrahydrate results in the formation of a nickel(II) complex (1). The ligand (LH) has been converted into a heterocyclic moiety, 9-methoxy-2,3-dihydro-1,4-benzoxyzepine (L) in 1 and coordinated to nickel(II) ion. Ligand substitution reaction of 1 with 3-aminopyridine leads to the formation of 3-aminopyridine derivative of complex 1, [{3-(NH2-Py)}4Ni(H2O)2]Br2⋅2(CH2Cl2) (2). Complexes 1 and 2 were characterized by using standard analytical techniques and their solid-state structures were confirmed by single crystal X-ray diffraction studies. Complex 1 crystallizes in orthorhombic space group Pccn with cell dimensions of a = 7.8483(10) Å, b = 30.662(3) Å, c = 9.3872(11) Å, Z = 4 and complex 2 crystallizes in orthorhombic space group Fddd with cell dimensions of a = 8.8108(4) Å, b = 21.0583(11) Å, c = 34.1913(17) Å, Z = 8. The optical properties and thermogravimetric analyses of complexes 1 and 2 are also reported.