The unsymmetrical N-heterocyclic ligand 1-[(benzotriazol-1-yl)methyl]-1H-1,3-imidazole (bmi) has three potential N-atom donors and can act in monodentate or bridging coordination modes in the construction of complexes. In addition, the bmi ligand can adopt different coordination conformations, resulting in complexes with different structures due to the presence of the flexible methylene spacer. Two new complexes, namely bis{1-[(benzotriazol-1-yl)methyl]-1H-1,3-imidazole-κN}dibromidomercury(II), [HgBr(CHN)], and bis{1-[(benzotriazol-1-yl)methyl]-1H-1,3-imidazole-κN}diiodidomercury(II), [HgI(CHN)], have been synthesized through the self-assembly of bmi with HgBr or HgI. Single-crystal X-ray diffraction shows that both complexes are mononuclear structures, in which the bmi ligands coordinate to the Hg ions in monodentate modes. In the solid state, both complexes display three-dimensional networks formed by a combination of hydrogen bonds and π-π interactions. The IR spectra and PXRD patterns of both complexes have also been recorded.

Subtle modifications of N-donor ligands can result in complexes with very different compositions and architectures. In the complex catena-poly[[bis{1-[(1H-benzotriazol-1-yl)methyl]-1H-imidazole-κN}copper(II)]-μ-benzene-1,3-dicarboxylato-κO,O:O], {[Cu(CHO)(CHN)(HO)]·2HO}, each Cu ion is six-coordinated by two N atoms from two crystallographically independent 1-[(1H-benzotriazol-1-yl)methyl]-1H-imidazole (bmi) ligands, by three O atoms from two symmetry-related benzene-1,3-dicarboxylate (bdic) ligands and by one water molecule, leading to a distorted CuNO octahedral coordination environment. The Cu ions are connected by bridging bdic anions to generate a one-dimensional chain. The bmi ligands coordinate to the Cu ions in monodentate modes and are pendant on opposite sides of the main chain. In the crystal, the chains are linked by O-H...O and O-H...N hydrogen bonds, as well as by π-π interactions, into a three-dimensional network. A thermogravimetric analysis was carried out and the fluorescence behaviour of the complex was also investigated.

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