Direct C–N Coupling in an in Situ Ligand Transformation and the Self-Assembly of a Tetrametallic [Ni^II₄] Staircase

A [Ni^II₄] 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 HL3^2– and HL4^2–, allowing the [Ni₄] formation. Variable-temperature magnetic behavior of a [Ni₄] complex reveals antiferromagnetic interactions with stabilization of a diamagnetic ground state (S_T = 0).