A Spin-Frustrated Azide- and Alkoxide-Bridged Heterobimetallic Mixed-Valence MnIIMnIII2NiII4 Disc with S = 17/2 or 19/2

Seven-membered homometallic FeIII7, MnIII3MnII4 coordination clusters were previously reported to be spin-frustrated molecular discs. Herein, a mixed bimetallic and mixed-valence dicationic [MnIIMnIII2NiII4(N3)4(hmp)10](NO3)2 (12+(NO3)2) was isolated in pure form without scrambling of Ni/Mn ions. It was structurally characterized by single-crystal X-ray single-crystal diffraction. The presence of MnII ions at the center of the disc has been confirmed by EPR measurements. The magnetic studies suggest that complex 12+(NO3)2 possesses spin frustration with spin ground states S = 17/2 and 19/2, which has been studied and supported by DFT calculation. The purity of 12+(NO3)2 was confirmed by powder XRD measurements, and the ratio of Ni:Mn = 4:3 was further determined by SEM-EDX analysis.