Hexacyanometalate Molecular Chemistry : Trinuclear CrNi2 Complexes; MicroSQUID Magnetisation Studies of Intermolecular Interactions

摘要

Three different CrNi2 complexes were synthesized. They differ from each otherby the nature of the terminal ligand and of the counter anion :[Cr(CN)4[CN-Ni(tetren)]2]Cl, that crystallizes in two differentcrystallographic systems and [Cr(CN)4[CN-Ni(dienpy2)]2](ClO4). The ground statespin value is 7/2 for the three systems (ferromagnetic interaction betweenchromium(III) and nickel(II) ions). The magnetisation of the three CrNi2complexes was measured using an array of micro-SQUIDs in a temperature rangebetween 0.04 K and 7 K, under a magnetic field up to 1 T. The three samplespresent a three dimensional magnetic ordering. The correlation between thestructure and the intermolecular coupling is analysed in terms of sterichindrances of the terminal ligand, orientation of the molecules in the unitcell (canted structure) and crystal symmetry.