Cu(II) and Ni(II) complexes with a tri-, tetra- or hexadentate triethanolamine ligand: Structural characterization and properties

Abstract

One Cu(II) (1) and two Ni(II) (2,3) novel compounds based on triethanolamine have been obtained and characterized by elemental and spectral analyses. Single-crystal X-ray crystallography has revealed that the crystal structure of compound 1 results from co-crystallization of ionic dinuclear [Cu2(H3L)2Cl2]Cl2 (1a) and molecular tetranuclear [Cu4(HL)2Cl4] (1b) species in a 1:0.036 ratio, both possessing an atrane structure. The molecular structure of [Ni2(H3L)2Cl2]Cl2 (3) resembles the compound [Cu2(H3L)2Cl2]Cl2 (1a). In both centrosymmetric dinuclear complexes, each metal atom exhibits an octahedral Cl2NO3 coordination provided by a tetradentate non-deprotonated triethanolamine ligand and two bridging chloride anions. The compound [Ni(H3L)2]Cl2 (2) has an ionic crystal structure, where triethanolamine acts as a non-deprotonated tridentate ligand, one of the OH-groups not being involved in coordination to the Ni atom. Analysis of the magnetic susceptibility results for compounds 1–3 reveals the presence of an antiferromagnetic interaction in the case of the Cu-based dimer 1 (J=−1.99(7)cm−1, g=2.07(9)) and a ferromagnetic interaction for the Ni-based dimer 3 (J=+7.17(3)cm−1, g=2.35(2)) with the ground state S=2. A significant zero field splitting (ZFS) effect was found for the Ni(II)-based complexes (D=−6.5cm−1, E=0.4cm−1). The thermal stability of the compounds was studied under a nitrogen atmosphere. The biocidal activities against some fungi (Aspergillus niger ATCC 53346, Penicillium frequentans ATCC 10110, Alternaria alternate ATCC 8741) and bacteria (Pseudomonas aeroginosa ATCC 27813 and Bacillus sp. ATCC 15970) were also evaluated. The moisture behavior of the obtained crystalline compounds was studied by dynamic water vapor sorption analysis.