Studies on the Magnetic Ground State of a Spin Möbius Strip

Here we report the synthesis, structure and detailed characterisation of three n ‐membered oxovanadium rings, Na n [(V=O) n Na n (H 2 O) n (α, β, or γ‐CD) 2 ]⋅ m  H 2 O ( n =6, 7, or 8), prepared by the reactions of (V=O)SO 4 ⋅ x  H 2 O with α, β, or γ‐cyclodextrins (CDs) and NaOH in water. Their alternating heterometallic vanadium/sodium cyclic core structures were sandwiched between two CD moieties such that O‐Na‐O groups separated the neighbouring vanadyl ions. Antiferromagnetic interactions between the S =1/2 vanadyl ions led to S =0 ground states for the even‐membered rings, but to two quasi‐degenerate S =1/2 states for the spin‐frustrated heptanuclear cluster.