Pentacoordinate Ni(II) complex: Synthesis, crystal structure and magnetism

Ni(II) complex [Ni(na-dmdpa)] (H2(na-dmdpa) =1,1 '-((1E,1 ' E)-(((methylazanediyl)bis(propane-3,1iyl))bis(aza-neylylidene))bis(methaneylylidene))bis(naphthalen-2-ol) has been synthesized using Schiff-base type pentadentate ligand formed by condensation of 2-hydroxynaphthaldehyde with 3,3 '-diamino-N-methyldipropylamine. The crystal structure is built up of com-plex molecules [Ni(na-dmdpa)]. The Ni(II) centre exhibits pentacoordination and its coordination sphere is formed by deprotonated Schiff base acting as doubly chelating pentadentate dianionic ligand. Calculated tau value for complex [Ni(na-dmdpa)] indicates that the coordination polyhedron is an intermediate between trigonal bipyramid and square pyramid. Complex is stable at RT. From the magnetic study follows that the axial zero-field splitting parameter is significantly negative (D/hc =-51 cm-1) and the value of rhombicity is moderate (E/hc =2.4 cm-1). Theoretical calculations support the magnetic experimental result. The out-of-phase component of the AC susceptibility is silent