Twists to the Spin Structure of the Ln₉‑diabolo Motif Exemplified in Two {Zn₂Ln₂}[Ln₉]{Zn₂} Coordination Clusters

Two pentadecanuclear Zn₄Ln₁₁ [with Ln = Gd­(1) or Dy­(2)] coordination clusters, best formulated as {Zn₂Ln₂}­[Ln₉]­{Zn₂}, are presented. The central {Ln₉} diabolo core has a {Zn₂Ln₂} handle motif pulling at two outer Ln ions of the central core via two {ZnLn} units, which also invest the system with C₂ point symmetry. The resulting cluster motif is supported on two Zn “feet”, corresponding to the {Zn₂} unit in the formula. A thorough investigation of the magnetic properties in the light of the properties of previously reported {Ln₉} diabolo compounds was undertaken. Up to now, the spin structure of such diabolo motifs usually proves ambiguous. Our magnetic studies show that the orientation of the central spin in the {Gd₉} diabolo plays a decisive role. In stabilizing the core by attachment of the {Zn}²⁺ “feet” and using the C₂ symmetry related {ZnGd}⁵⁺ handles to influence the spin direction of the central Gd of the {Gd₉} diabolo, we can understand why the “naked” {Gd₉} diabolo shows ambiguous spin structure. This then allowed us to elucidate the single-molecule magnetic (SMM) properties of the Dy-based compound 2 through disentangling the magnetic properties of the isostructural Gd-based compound 1.