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A New Triazine-Based Tricompartmental Ligand for Stepwise Assembly of Mononuclear, Dinuclear, and 1D-Polymeric Heptacoordinate Manganese(II)/Azido Complexes



A new ligand 2,4,6-tris[{N-methyl-N′-(pyridine-2-yl)methylidene}hydrazino]-1,3,5-triazine (L) has been synthesized from cyanuric chloride in two steps. The threefold symmetric L features three potentially tridentate {N3} binding compartments. However, with MnII it binds a single metal ion using one of the triazine N atoms and two chelate arms. This {N5} set forms the equatorial plane of a distorted pentagonal-bipyramidal metal ion environment, with a variety of ligands in axial positions. Five such MnII complexes have been isolated and characterized by X-ray crystallography. Complex 1 features axial water and nitrato-O ligands. In 5, the latter is replaced by dicyanamide. Two terminal azido ligands are found in 3. Depending on the ratio of L:MnII:azide, L may also adopt a bridging mode to give the dimeric species [{(H2O)MnIIL}(μ-1,3-N3){LMnII(NO3)}](NO3)2 (2) or a 1D coordination polymer [(LMnII)(μ-1,3-N3)]n(NO3)n (4). The basic {LMnII} entity undergoes little structural variation in the series of complexes, which can be viewed as structural snapshots for the assembly of a MnII/azido polymeric chain from well-defined mononuclear building units. Magnetic coupling along the μ-1,3-azido linkage in the dimeric and 1D-extended complexes is weakly antiferromagnetic; the strength of the coupling is rationalized on the basis of the Mn–N–N angles and the dihedral angle τ along the azide ligand.