Structural diversity in Cu(II), Cd(II) and Hg(II) coordination complexes with the rigid N,N′-bis(2/3-aryl)-1,4-benzenedicarboxamide ligand

The syntheses and structures of a series of metal complexes, namely Cu2Cl4(L1)(DMSO)2·2DMSO (L1 = N,N′-bis(2-pyridinyl)-1,4-benzenedicarboxamide), 1; {[Cu(L2)1.5(DMF)2][ClO4]2·3DMF}∞ (L2 = N,N′-bis(3-pyridinyl)-1,4-benzenedicarboxamide), 2; {[Cd(NO3)2(L3)]·2DMF}∞ (L3 = N,N′-bis-(2-pyrimidinyl)-1,4-benzenedicarboxamide), 3; {[HgBr2(L3)]·H2O}∞, 4, and {[Na(L3)2][Hg2X5]·2DMF}∞ (X = Br, 5; I, 6) are reported. All the complexes have been characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. Complex 1 is dinuclear and the molecules are interlinked through S⋯S interactions. In 2, the Cu(II) ions are linked through the L2 ligands to form 1-D ladder-like chains with 60-membered metallocycles, whereas complexes 3 and 4 form 1-D zigzag chains. In complexes 5 and 6, the Na(I) ions are linked by the L3 ligands to form 2-D layer structures in which the [Hg2X5]− anions are in the cavities. The L2 ligand acts only as a bridging ligand, while L1 and L3 show both chelating and bridging bonding modes. The L1 ligand in 1 adopts a trans-anti conformation and the L2 ligand in 2 adopts both the cis-syn and trans-anti conformations, whereas the L3 ligands in 3–6 adopt the trans conformation.

Graphical abstractThe synthesis and structures of a series of metal complexes containing the rigid ligands N,N′-bis(2-pyridinyl)-1,4-benzenedicarboxamide) (L1), N,N′-bis(3-pyridinyl)-1,4-benzenedicarboxamide) (L2) N,N′-bis-(2-pyrimidinyl)-1,4-benzenedicarboxamide) (L3) are reported, which show dinuclear, 1D ladder type and zigzag chain, and 2D grid structures. The differences of the L1, L2 and L3 ligands in bonding mode and conformation play important roles in determining the structural diversity.Figure optionsDownload full-size imageDownload as PowerPoint slide