Magnetic Investigations of Spin-Free Cobaltous Complexes. I. Tetrahalo Cobalt(II) Ions

The magnetic susceptibilities of six spin-free tetrahalo complexes of bivalent cobalt, CoX4—2 (X=Cl—, Br—, I—), have been investigated over a temperature range and found to exhibit satisfactory dependence on the Curie-Weiss law. The magnetic moments were found to be in the order predicted by crystal field theory, viz., I—>Br—>Cl—, whereas previously reported moments for these ions are in the reverse direction. The origin of this trend is briefly discussed. Evidence obtained from the magnetic measurements is offered in support of the assignments by Ballhausen and Jørgensen and by Orgel of the crystal field bands in CoCl4—2.