Synthesis and physicochemical characterization of two lead(II) complexes with O-, N-donor ligands. Lone pair functionality and crystal structure

Abstract A dinuclear [Pb 2 (4-CHO-5-MeIm) 6 (NO 3 ) 2 ](NO 3 ) 2 ( 1 ) and a polynuclear [Pb(2-pzc) 2 (H 2 O)] n ( 2 ) complexes (where 5(4)-carbaldehyde-4(5)-methylimidazole (5(4)-CHO-4(5)-MeIm) and pyrazine-2-carboxylic acid (2-pzcH)) have been synthesized and characterized by elemental analysis, IR spectroscopy and X-ray crystallography. Structural determination for complex 1 reveals a cationic species [Pb(4-CHO-5-MeIm) 3 ] 2+ connected through bridging nitrate(V) ions. There are also an uncoordinated nitrate ions as counterions. Complex 2 is a three-dimensional architecture consisting of Pb 6 O 12 building units. The pyrazine-2-carboxylato ligand behaves as a chelating agent and a bi-connective bridge. The coordination polyhedra around lead(II) ion could be described as a distorted docecahedron ( 1 ) or monocapped trigonal prism ( 2 ). The luminescent properties of 1 and 2 investigated in the solid state at room temperature indicate structure-dependent photoluminescent properties. The DFT calculations and the X-ray structural data point on rather hemidirected type of coordination around Pb(II) ions of 1 and 2 .