Direct C–N Coupling in an in Situ Ligand Transformation and the Self-Assembly of a Tetrametallic [NiII4] Staircase

A [NiII4] staircase complex was serendipitously prepared from the reaction of the binucleating Schiff base proligand 2,6-bis­[[(3-hydroxypropyl)­imino]­methyl]-4-methylphenol (H3L2) and 3,5-dimethylpyrazole (Me2pzH) with nickel­(II) nitrate in a reaction at room temperature, initially aimed to yield a dinuclear complex. From a room temperature metal ion/ligand reaction, the proligand H3L2 in situ transformed to modified forms HL32– and HL42–, allowing the [Ni4] formation. Variable-temperature magnetic behavior of a [Ni4] complex reveals antiferromagnetic interactions with stabilization of a diamagnetic ground state (ST = 0).