A Cationic Tetranuclear [Ni II 4 (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 Ni 4 O 2 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 J 1 = 55.8 cm −1 , J 2 = −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)