Herein, two new groups of isomeric bimetallic nickel(II) and copper(II) complexes containing pyrazine or pyrimidine rings are synthesized and examined. The complexes exhibit liquid-crystalline columnar phases in a broad temperature range. For the copper(II) complexes, super-exchange coupling between two Cu(II) ions is observed. For the pyrimidine derivative in which the paramagnetic Cu(II) ions are separated only by three atoms, an antiferromagnetic spin alignment is detected. When the distance between Cu(II) ions increases to four atoms in the pyrazine derivative, the magnetic interaction becomes significantly weaker.

The magnetic properties of Ni(II) and Cu(II) complexes were measured. In the case of Ni(II) samples strong enhancement of the magnetic susceptibility below 23 K was observed. The model of structural transition was proposed to explain this behavior.