A phenol-based macrocyclic compartmental ligand, (L2;2)2-, having N(amine)22and N(imine)2O2 metal binding sites sharing two phenolic oxygen atoms, has formed the following heterodinuclear MIINiII complexes: [CoNi (L2;2)(AcO)]PF6·CH3CN (1), [NiNi(L2;2)(AcO)]PF6 (2), [CuNi(L2;2)(AcO)]PF6 (3) and [ZnNi(L2;2)(AcO)]PF6·CH3CN (4). Furthermore, [CuNi(L2:2)(CH3CN)](PF6)2 ·CH3CN (3′) was obtained when 3 was recrystallized from acetonitrile. X-ray crystallographic studies for 1, 2, 3′ and 4 demonstrate that the Ma resides in the N(amine)2O2 site and the NiII in the N(imine)2O2 site. The NiII in the N(imine)2O2 site has a planar geometry and is diamagnetic in all the complexes. The CoII of 1 and the NiII of 2 in the N(amine)2O2have a six-coordinate geometry together with a bidentate acetate group. The CuII in 3′ has a five-coordinate geometry together with one acetonitrile molecule, and the ZnII 4 has a square-pyramidal geometry together with a unidentate acetate group. Complex 3′ in DMF combines 1-methylimidazole (MeIm) at the axial site of the NiII and the Melm adduct in frozen DMF solution at 77.4 K shows EPR signals of g∥ = 2.06 and g⊥ = 2.26 with a multi-line structure superimposed on the g∥ component (A∥ = 15.8 × 10-4 cm-1). The EPR signals are ascribed to the spin-doublet ground state (ST = 1/2) of antiferromagnetically coupled CuII(S = 1/2) - NiII(S = 1), and the multi-line structure is explained by considering hyperfine interaction with Cu nucleus (ACu = 50.0 × 10-4 cm-1) and superhyperfine interaction with N nucleus of Melm (AN = 15.0 × 10-4 cm-1).
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