Polynuclear Nickel(II) Complexes: Preparation and Magnetic Properties of NiII₄, NiII₅, and NiII₆ Species with Ligands containing O∩X∩O (X = S, Se or N) Donor Atoms

A family of bisphenol‐containing ligands with XO 2 donor atoms, where X = S, Se, or N, yields [Ni II ] 4 ( 1 ) and ( 2 ), [Ni II ] 5 ( 3 ), and [Ni II ] 6 ( 4 ) complexes. Complex 2 , 3 , and 4 have been structurally characterised by X‐ray diffraction. The compounds were characterised spectroscopically and by variable‐temperature (2−295 K), variable‐field (1, 4, and 7 T) magnetic susceptibility measurements. Analysis of the magnetic data shows predominant ferromagnetic interactions between the nickel centres ( S Ni = 1) indicating “high‐spin” ground states for 1 , 2 , and 3 , whereas complex 4 shows antiferromagnetic interactions. A plot of J vs. Ni−O−Ni angles for all structurally characterised Ni 4 O 4 cubane cores, including 2 , irrespective of their symmetry, shows a large variation of J values within a small range of Ni−O−Ni angles. A simple two‐ J model was found to be adequate to describe the magnetic properties of the hexanuclear complex, 4 . (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)