Synthesis and Magnetism of Co2III₂IIICo5II₅II and Co2III₂IIICo6II₆II Complexes, and the Role of the Free Choice of Local Coordinate Frames for Interpreting Magnetic Parameters

Two new polynuclear high‐spin Co coordination clusters have been synthesised using the proligand ‐allyldiethanolamine (2,2′‐(allylazanediyl)bis(ethan‐1‐ol), adeaH). The heptanuclear coordination cluster [CoCo(adea)(‐OH)(‐OMe)(‐OMe)(piv) (MeOH)]2MeOH () possesses a disk‐like core motif and was used as a starting material for the syntheses of the octanuclear coordination cluster [CoCo(adea)(‐OH)(piv)]2Hpiv2MeCN (). From magnetic measurements a magnetic model could be developed which fits the versus and versus curves accurately. In order to rationalise the magnetic properties of it was found essential to consider the consequences of the freedom to choose the local coordinate frames used for describing the individual Co centres in the cluster. The far‐reaching implications of this for the interpretation of magnetic parameters derived from magnetic modelling of clusters containing highly‐anisotropic metal ions are discussed.