Synthesis and crystal structures of metallomacrocyclic and helical Hg(II) complexes with two bis(pyridylurea) ligands

Abstract Two complexes, [Hg 2 L 1 2 Cl 4 ]·2DMF ( 1 ) and {[Hg L 2 Br 2 ]·2DMSO} n ( 2 ), have been synthesized and characterized from two flexible bis(pyridylurea) ligands ( L 1 and L 2 ) with mercury(II) halides respectively. In the two complexes, both Hg(II) centers adopt four-coordination mode, but they present different architectures with slightly adjusted 3- and 4-position of nitrogen atom in the pyridyl ring. Complex 1 exists as a centrosymmetric metallamacrocycle with L 1 as bidentate ligand bridging two HgCl 2 units, and complex 2 exists as a 1 D helical chain coordination polymer with L 2 as bridging ligand and Br − as terminal ligand, which indicates that the nature of the ligand plays an important role in the coordination networks.