Solid State EPR Studies on Bis(1,2-dithiosquarato) cuprates(II): a Structure – Spectroscopy Relationship

1,2-Dithiosquaratometalates (M = Cu, Ni) are available by direct synthesis from metal salts with dipotassium-1,2-dithiosquarate and the appropriate counter cations. For EPR measurements in solid state (powder or single crystals) a diamagnetic dilution of the paramagnetic centers by isostructural host lattices is necessary to separate the magnetic centers from each other to prevent interactions. The X-ray structures of two potential diamagnetic hosts (Ph4P)2[Ni(dtsq)2]1 and [(Ph3P) 2N]2[Ni(dtsq)2]2 as well as the structures of two paramagnetic[Cu(dtsq)2]2– complexes with sterically demanding counter cations [(Ph3P) 2N]2[Cu(dtsq)2]4 and [p–C6H4(CH2Ph3)2][Cu(dtsq)2]5 are discussed. The copper complexes 4 and 5 as well as (Ph4P)2[Cu(dtsq)2]3 were studied by solid state EPR spectroscopy as powders or single crystals and the parameters are compared to those of related complexes in diamagnetic host lattices. Metal-metal distances of 11–13 إ in the copper complexes separate the paramagnetic centres sufficiently and reduce the interactions to enable a well resolved hyperfine structure and to determine the tensor parameters of the magnetic g- and ACu-tensors.