Large and negative magnetic anisotropy in pentacoordinate mononuclear Ni(II) Schiff base complexes

摘要: A series of pentacoordinate Ni(II) complexes the general formula [Ni(L5)] (1–6) with various pentadentate Schiff base ligands H2L5 (originating in a condensation aromatic ortho-hydroxy-aldehydes and aliphatic triamines) was synthesized characterized by X-ray structure analysis magnetometry. The alternations substituents on H2L parent ligand resulted geometry varying between square-pyramid trigonal-bipyramid. In compounds whose chromophore is closer to trigonal-bipyramid, large negative uniaxial anisotropy (D = −64 cm−1) identified. Moreover, simple linear expression for axial zero-field splitting (ZFS) parameter, D/cm−1 32.7(4.8) − 151(10)τ, proposed, where τ (in degrees) stands Addison parameter. results magnetic were also supported ab initio CASSCF/NEVPT2 calculations ZFS parameters D E, g tensors. Despite D-values reported compounds, slow relaxation magnetization not observed either zero or non-zero static field, thus no single-molecule behaviour detected.