Stern-Gerlach study of multidecker lanthanide-cyclooctatetraene sandwich clusters

Multilayer lanthanide-cyclooctatetraene organometallic clusters, Ln _n(C₈H₈)_m, (Ln = Eu, Tb, Ho, Tm; n = 1 - 7; m = n - 1, n, n + 1) were produced by a laser vaporization synthesis method. The magnetic deflections of these organometallic sandwich clusters were measured by a molecular beam magnetic deflection technique. Most of the sandwich species displayed one-sided deflection, while some of smaller Ln-C ₈H₈ clusters showed symmetric broadening without or with only very small (or absent) net high-field deflection. In general, the total magnetic moments, calculated from the magnitude of the beams deflections, increase with the number of lanthanide atoms (i.e., with increasing sandwich layers); however for Tb-, Ho-, and Tm-C₈H₈ clusters with n > 3, the suppression of the magnetic moments was observed, possibly through antiferromagnetic interactions. For Eu-C₈H₈ clusters, we observe a linear increase of the magnetic moments with the number of Eu atoms up to n = 7, with average magnetic moment per Eu atom around 7 μ_B - similar to that displayed by conventionally synthesized mononuclear Eu ^IIC₈H₈ complexes, indicating that Eu atoms exist as Eu²⁺ ions in the full sandwich Eu_n(C ₈H₈)_n+1 clusters. These results suggest that Eu_n(C₈H₈)_n+1 is a promising candidate for a high-spin, one-dimensional building block in organometallic magnetic materials.