Synthesis and thermal, fluorescence and structural studies of mixed-ligand lead(II) complexes with 2,2′-diamino-5,5′-dimethyl-4,4′-bithiazole

Abstract

The synthesized ligand (DADMBTZ = 2,2′-diamino-5,5′-dimethyl-4,4′-bithiazole) is used for preparing these two new 1 : 2 adducts of [Pb(DADMBTZ)₂(NO₃)X] X = CH₃COO⁻ (1) and (2) complexes. Characterization was done by IR, ¹H- and ¹³C-NMR spectroscopy, elemental analysis, and single crystal X-ray determination. UV-Vis and fluorescence spectra were studied. Thermal stabilities of 1 and 2 were studied by thermal gravimetric (TG) and differential thermal analysis (DTA). The coordination number of Pb in 1 is seven (four by the chelating DADMBTZ, two oxygens of acetate and one oxygen of nitrate), whereas in 2 it is five (four by the chelating DADMBTZ and one oxygen of nitrate). Coordination geometries of 1 and 2 show a possible vacant site around Pb(II), occupied possibly by a stereoactive lone pair of electrons on lead(II); coordination around lead is hemidirected with a significant gap trans to chelating DADMBTZ, nitrate, and acetate. Both 1 and 2 make 3-D networks via N–H ··· O and N–H ··· N hydrogen bonds; O–H ··· O hydrogen bonds are found in the network for 1.

Keywords:

• X-ray
• Fluorescence
• Thermal
• Coordination
• Bithiazole
• Hemidirected

Acknowledgments

The University of Tehran and Tarbiat Modares University Research Council supported this study. We thank the Institute of Organoelement Compounds of the Russian Academy of Science for determining the crystal structure by X-ray crystallography.