摘要：

The magnetic behavior of the clusters [(PhSiO)Cu(OSiPh)]·6EtOH (), Na[(PhSiO)Cu]·8BuOH (), and K[(CHSiO)Cu]·6BuOH () has been investigated by combined magnetic susceptibility measurements and variable-temperature EPR techniques (9.25 and 245 GHz). The six copper(II) ions in the core of , which approaches 6/symmetry, are ferromagnetically coupled as a result of the geometry at the bridging siloxanolate oxygen atoms (Cu−O−Cu = 91.5−94.6°; = −42 cmwith = ·, = ). The ground = 3 spin state is split in zero field mainly due to anisotropic exchange contributions (= 0.30 cm). Notably, both the magnitude and the sign of the zero-field splitting parameter have been determined from HF-EPR spectra. Large antiferromagnetic Cu-Cu interactions (∼ 200 cm) and an = 0 ground state have been detected in the tetranuclear clusters and as a consequence of the larger Cu−O−Cu angles. The results presented in the paper are relevant to the search for new molecule-based magnetic materials.

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