LAUSR

Abstract The work in the present investigation reports the syntheses, crystal structures, ESI-MS (positive) and variable-temperature and variable-field magnetic properties of two Ni4O4 cubane compounds of composition [NiII4L2(µ1,3-HCO2)2](ClO4)2·2H2O (1) and [NiII4L2(µ1,3-o-ClPhCO2)2](ClO4)2·3H2O (2) derived from the Robson type tetraiminodiphenol macrocyclic ligand H2L (2 + 2 condensation of 4-ethyl-2,6-diformylphenol and 2,2-dimethyl-1,3-diaminopropane). All the four oxygen atoms of the distorted cubane are phenoxido oxygen atoms, coming from two deprotonated macrocycle, [L]2−, i.e., these compounds are Ni4(μ3–phenoxido)4 cubanes. The nickel(II) centers in each of the two pairs in two opposite faces of the cube are additionally bridged by a syn–syn carboxylate, formate in 1 and o-chlorobenzoate in 2. Variable-temperature and variable-field magnetization data reveal an overall antiferromagnetic interaction in both 1 and 2, where two of the six pathways are ferromagnetic (4.06 cm−1 in 1 and 1.58 cm−1 in 2) and the remaining four pathways are antiferromagnetic (−3.03 cm−1 in 1 and −1.55 cm−1 in 2). The possibility of a J versus NiII–O(phenoxo)–NiII angle correlation and the roles of carboxylate moiety as well as energy difference between the first excited state and ground state on magnetic properties have been discussed.