Nickel(II) complexes with bridged polyamines

Three nickel(II) complexes [Ni2(μ-trien)(trien)2](ClO4)4 (1), {[Ni2(μ-tren)2(tren)](ClO4)4·3,25H2O}n (2) and [Ni3(μ-tren)2(tren)2(H2O)2]Cl6·2H2O (3) (trien = N,N′-bis(2-aminoethyl)ethane-1,2-diamine, tren = N,N′-bis(2-aminoethyl)-1,2-ethanediamine) were synthesized and structurally characterized. Complex 1 consists of dimeric [Ni2(μ-trien)(trien)2]4+ cation and perchlorate anions, compound 2 contains polymer chain of cation {[Ni2(μ-tren)2(tren)]4+}n, perchlorate anions and uncoordinated water molecules, and structure of 3 consists of [Ni3((μ-tren)2(tren)2(H2O)2]6+ cation, chloride anions and uncoordinated water molecules. All compounds exhibit octahedrally coordinated nickel atoms. Two nickel(II) atoms of [Ni2(μ-trien)(trien)2]4+ cation in 1 are bridged through one trien ligand, which is bidentate to both nickel(II) atoms. The central Ni(II) atom in complex 3 is associated with peripheral atoms with one arm of tren ligand bonded in tridentate fashion, similarly as two nickel(II) atoms in polymer of complex 2. The magnetic behaviour of 1 and 2 complexes have been investigated in terms of magnetic susceptibility and magnetization. The magnetic analyses confirmed weak antiferromagnetic exchange between paramagnetic Ni(II) centres. The experimental observations were further confirmed and studied by DFT method at B3LYP/def2-TZVP level of theory for all compounds.

Three Ni(II) complexes with aliphatic tetradentate ligands have been synthesised and characterized by means of elemental analysis, IR, magnetic measurements and single-crystal X-ray analysis. The structural analyses revealed dinuclear molecular structure in case of trien ligand, [Ni2(μ-trien)(trien)2](ClO4)4 (1), while polymeric and trinuclear compounds {[Ni2(μ-tren)2(tren)](ClO4)4·3,25H2O}n (2) and [Ni3(μ-tren)2(tren)2(H2O)2]Cl6·2H2O (3) were formed by using tren ligand. The magnetic behaviour of 1 and 2 complexes have been investigated in terms of magnetic susceptibility and magnetization. The magnetic analyses confirmed weak antiferromagnetic exchange between paramagnetic Ni(II) centres.Figure optionsDownload as PowerPoint slide