Syntheses, Crystal Structures, and Magnetic Properties of a Series of Defect‐Dicubane Tetranickel(II) Systems with Variable, Mixed, and Interchangeable µ 3 ‐Core Ligands

The article describes syntheses, crystal structures and magnetic properties of six defective dicubane type Ni II 4 clusters of compositions [Ni II 4 (HL 1 ) 2 (µ 3 ‐X) 2 (µ 1,1 ‐N 3 ) 2 (µ 1,3 ‐carboxylato) 2 ] · n H 2 O ( 1 , X = OMe – , carboxylato = o ‐benzoylbenzoato, n = 0; 2 , X = {(OMe – ) 0.83 (N 3 – ) 0.17 }, carboxylato = phenyl acetato, n = 2; 3 , X = {(OMe – ) 0.80 (N 3 – ) 0.20 }, carboxylato = salicylato, n = 0; 4 , X = OH – , carboxylato = o ‐benzoylbenzoato, n = 2; 5 , X = {(N 3 – ) 0.58 (OMe – ) 0.42 }, carboxylato = o ‐benzoylbenzoato, n = 2) and [Ni II 4 (HL 1 ) 2 (µ 1,1,1 ‐N 3 ) 2 (µ 1,1 ‐N 3 ) 2 (N 3 ) 2 (H 2 O) 2 ] · 4DMF ( 6 ), where H 2 L 1 is 2‐Formyl‐6‐{(2‐hydroxy‐1,1‐dimethyl‐ethylimino)‐methyl}‐4‐ethyl‐phenol, and this is the partially hydrolyzed product of initially employed ligand H 3 L, 2,6‐bis‐{(2‐hydroxy‐1,1‐dimethyl‐ethylimino)‐methyl}‐4‐ethyl‐phenol. Each of the two compartments of each [HL 1 ] – in 1 – 6 is occupied by a Ni II ion, to form a Ni II 2 fragment. The common bridges between the two metal ions in a dinuclear fragment are µ‐phenoxo of [HL 1 ] – and one µ 3 ‐core ligand (methoxo/hydroxo/mixture of methoxo and µ 1,1,1 ‐azido) while the additional bridge in 1 – 5 is a µ 1,3 ‐carboxylato. Two dinuclear fragments are interlinked by two µ 1,1 ‐azido and two µ 3 ‐core ligands. Interestingly, the µ 3 ‐methoxo compound 1 and the µ 3 ‐hydroxo compound 4 are interconvertible in both ways as the function of the solvents. Variable‐temperature and variable‐field magnetic studies reveal overall ferromagnetic interactions in each of 1 – 6 .