A Cationic Tetranuclear [NiII4(MeOH)2(pko)6]2+ Cluster Showing Antiferro- and Ferromagnetic Features

The majority of reported nickel tetranuclear clusters have a dicubane-like structural core. The compound presented here is the second example possessing an Ni4O2 core based on a chair or butterfly “out-of-face” topology. This compound also belongs to the family of compounds characterized as metallacrowns with an [Ni−N−O−]n linkage and is the only example with three Ni−O−N−Ni strands bridging the nickel atoms. The values obtained from the fitting procedure are J1 = 55.8 cm−1, J2 = −67.2 cm−1, g = 2.2, ρ = 1.1%. These values suggest the presence of both ferromagnetic and antiferromagnetic interactions, while a small paramagnetic impurity is also present. This magnetic behaviour with antiferromagnetic internal coupling and ferromagnetic spin-alignment is the second example in the literature and the first in the metallacrown family. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)