The tetranuclear cobalt complex [Co(NPtBu3)]4 (tBu = tert-butyl) possessing metal centers in low-coordinate environment and direct metal-metal interaction was characterized by SQUID magnetometry. The cluster features a well-isolated high spin ground state S = 4, which persists at 300 K, and large magnetic anisotropy. However, the easy plane magnetic anisotropy of the complex prevents slow magnetic relaxation and thus no resulting single-molecule magnet behavior. One-electron oxidation of the cluster yielded [{Co(NPtBu3)}4][B(C6F5)4] salt. The resulting oxidized complex possesses isolated high spin ground state S = 9/2, and large magnetic anisotropy. Ac susceptibility measurement indicates slow magnetic relaxation under zero applied field, with an effective Orbach barrier of 81 cm–1. Exceptionally, open magnetic hysteresis was observed below 3.6 K.

Enhanced magnetic anisotropy and single-molecule magnet behavior in tetranuclear clusters featuring low-coordinate cobalt centers

253rd National Meeting (2017)

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