Construction of a Novel Topological Frustrated System: A Frustrated Metal Cluster in a Helical Space

A novel topologically frustrated pentanuclear cluster helicate [{CuII(μ‐L)3}2CuII3(μ3‐OH)]3+(L−=3,5‐bis(2‐pyridyl)pyrazolate) has been synthesized and characterized. This cluster has a helical arrangement of ligands around the central metal core. Dzyaloshinsky–Moriya interactions are essential components to observe a gradual magnetization and forbidden transitions of high‐field/multi‐frequency (HF/MF)‐ESR. The origin of the magnetic anisotropy of this compound is influenced by its helical spin structure, and consequently, the Cu5‐cluster helicate introduces a unique magnetic anisotropy. This observation is a direct evidence of the topological part of the new spin phase in a magnetic system.