Preparation, Characterization of Some Lanthanide(III) Complexes of N'-(phenyl(pyridin-2-yl)methylene)nicotinohydrazide

Abstract

The present investigation describes the synthesis and structural study of the ligand N'-(phenyl(pyridin-2-yl)methylene)nicotinohydrazide (HL), which was used to generate two type complexes formulated as [Ln(HL)2(NO3)2(H2O)].(NO3) (Ln = La (1) and Pr (2)) and [Ln(HL)2(NO3)(H2O)2].(NO3)2 (Ln = Nd (3), Sm (4), Gd (5) and Tb (6)). The ligand and the complexes are characterized by NMR, UV-Visible and FTIR spectroscopies, conductivity measurements and room temperature magnetic moment measurements. The [La(HL)2(NO3)2(H2O)].(NO3) compound crystallizes in the orthorhombic space group Pbcn with the following unit cell parameters: a = 16.8634(8) Å, b = 8.0615(4) Å, c = 30.2833(15) Å, V = 4116.8(3) Å3, Z = 8, R1 = 0.049 and wR2 = 0.120. The structure reveals that two neutral ligand molecules in η3-mode, two bidentate nitrate groups in η2-mode and one water molecule coordinate the central La3+. Each organic molecules acts through one carbonyl oxygen atom, one azomethine nitrogen atom and one nitrogen atom from a pyridine ring. The lanthanide ion has a coordination number of 11 and the coordination environment can be described as distorted pentacapped trigonal prism. Numerous hydrogen bonds link the molecules into three-dimensional network.