The [2 × 2] grid tetranuclear Fe(II) and Mn(II) complexes: Structure and magnetic properties

Tetranuclear complexes, [Fe4(HL)4](ClO4)4·5H2O (1) and [Mn4(HL)4](ClO4)4·2MeCN·2H2O (2) with [2 × 2] rectangle and square grid structure were self-assembled using the flexible ligand, 1,5-bis(1-(pyridine-2-yl)ethylidene)carbonohydrazide. The structures and magnetic properties were characterized by single crystal X-ray diffraction and variable temperature magnetic susceptibility measurements, respectively. For 1, the iron(II) centers are in distorted octahedral environment with N4O2 or N5O coordination spheres through two bridging enolyl oxygen atoms and two bridging N-N single bonds. Whereas, for 2, all four manganese(II) centers are in a distorted octahedral geometry with N4O2 coordination spheres through enolyl oxygen atoms connecting two adjacent metal ions. The magnetic properties of 1 and 2 show intramolecular antiferromagnetic exchanges.