The effect of pH on the coordination sphere of Pb(II) ions and structural diversity of Pb(II) coordination polymers

Abstract Two new lead(II) coordination polymers, [Pb3(2,6-pda)3]n (1) and [NaPb2(2,6-pda)2(OH)(H2O)4]n (2) (2,6-H2pda ​= ​2,6-pyridyldicarboxylic acid) have been solvothermal synthesized and characterized by elemental analysis, IR, single crystal X-ray diffraction. Compound 1 shows a 3D framework structure with the point symbol of {411‧64}{48‧67}2. Compound 2 displays a 1D chain structure by Na(I) ions linking [Pb2(2,6-pda)2(OH)]- fragments. The structural diversity of 1 and 2 indicates that the pH value and anions play significant roles in construction of Pb(II)-CPs. Meanwhile, the hemi-directed or holo-directed coordination geometries rely on coordination numbers of Pb(II) ions. Furthermore, tetrel bonds can improve the structural stability of Pb(II) coordination polymers.