Synthetic and structural chemistry of nickel(II)/1-methylbenzotriazole complexes

Abstract

A systematic investigation of the NiX 2/Mebta (X = Cl, Br, NCS, NO 3; Mebta = 1-methylbenzotriazole) reaction system in various solvents is described. Particular emphasis has been placed on determining the influence of the Mebta: Ni 11 ratio on the identity of the reaction products. In the nitrate case, the influence of the water concentration in the reaction mixture on reaction products has also been investigated. These combined variations have led to the preparation of 14 discrete six-coordinate complexes with the formulae [Ni(NO) 3) 2(Mebta) 2], [Ni(NO 3)(H 2O) 2(Mebta) 2]NO 3, [Ni(H 2O) 4 (Mebta) 2](NO 3) 2, [Ni(NO 3) 2(Mebta) 3]·CH 3COCH 3, [NiX 2(Mebta) 4](X = ONO 2, NCS, Cl, Br), [NiX 2(Mebta) 2] n (X = Cl, Br), [NiX 2(MeOH) 2(Mebta) 2] (C = Br, NCS) and [NiX 2 (Mebta)] n (X = Cl, Br). Four complexes have been structurally characterized by single-crystal X-ray studies: cis-[Ni(NO 3) 2(Mebta) 2] ( 1), trans-[Ni(H 2O) 4)Mebta) 2](NO 3) 2 ( 3), mer-[Ni(NO) 3) 2((Mebta) 3]·CH 3COCH 3 ) 4) and trans-[Ni(NCS) 2(MeOH) 2(Mebta) 2] ( 6). Mebta behaves as a monodentate ligand binding through N(3). The structures of 3and 6 are stabilized by intermolecular hydrogen bonds. The new complexes were studied by thermal techniques, conductivity measurements, magnetic susceptibilities and spectroscopic (IR, ligand field) methods. Monomeric, trans pseudo-octahedral structures are assigned for the complexes [NiX 2(Mebta) 4] and [NiBr 2(MeOH) 2(Mebta) 2] in the solid state. Polymeric structures are suggested for [NiX 2(Mebta) 2] n and [NIX 2(Mebta)] n with NiX 4N 2 and NiX 5N coordination spheres, respectively.