Some mononuclear and dinuclear Ni(ii) complexes with tetradentate Schiff base ligands exhibit zero-field splitting and ferromagnetic coupling, respectively.

Four new complexes, [NiL(NO 3)]⋅CH 3 OH (1), [Ni 2 L 2 (μ-Cl) 2 ] (2), [Ni 2 L 2 (μ 1,1-NCO) 2 ] (3) and [Ni 2 L 2 (μ 1,1-N 3) 2 ] (4) were synthesized from a tetradentate Schiff base (HL), prepared from the condensation reaction of N,N-dimethyldipropylenetriamine and 5-bromosalicylaldehyde. X-ray crystallography reveals that 2-4 are isostructural and isomorphic dinickel(II) compounds with bridging chloride or pseudohalides. All these three dinickel(II) complexes exhibit ferromagnetic interaction through bridging chloride or pseudohalides and their coupling constants are in the order 4 > 2 > 3, a replication of the average strength of exchange interactions found in such complexes characterised magnetically. Most importantly, compound 3 is a precious addition to the only four known examples of this family, and unprecedented high degree of structural and magnetic resemblances observed in 2-4 is the major achievement of the present work.

Tetradentate ligands with {N4}-donor (L1 and L2) and {N3O}-donor (HL3) groups prepared from a traditional Schiff base condensation reaction of N,N-dimethyldipropylenetriamine with pyridine-2-aldehyde or 2-acetylpyridine or 3-ethoxysalicylaldehyde, respectively, were used...

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