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

Abstract

Two complexes, [Hg2L12Cl4]·2DMF (1) and {[HgL2Br2]·2DMSO}n (2), have been synthesized and characterized from two flexible bis(pyridylurea) ligands (L1 and L2) 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 L1 as bidentate ligand bridging two HgCl2 units, and complex 2 exists as a 1D helical chain coordination polymer with L2 as bridging ligand and Br− as terminal ligand, which indicates that the nature of the ligand plays an important role in the coordination networks.