Single-Molecule Magnets: High-Field Electron Paramagnetic Resonance Evaluation of the Single-Ion Zero-Field Interaction in a ZnII3NiII Complex

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• 作者：En-Che Yang ; Cem Kirman ; Jon Lawrence ; Lev N. Zakharov ; Arnold L. Rheingold ; Stephen Hill ; and David N. Hendrickson
• 刊名：Inorganic Chemistry
• 出版年：2005
• 出版时间：May 30, 2005
• 年：2005
• 卷：44
• 期：11
• 页码：3827 - 3836
• 全文大小：260K
• 年卷期：v.44,no.11(May 30, 2005)
• ISSN：1520-510X

文摘

High-field electron paramagnetic resonance spectra were collected at several frequencies for a single crystal of[Zn_3.91Ni_0.09(hmp)₄(dmb)₄Cl₄] (1), where dmb is 3,3-dimethyl-1-butanol and hmp^- is the monoanion of 2-hydroxymethylpyridine. This crystal is isostructural to [Ni₄(hmp)₄(dmb)₄Cl₄] (2), which has been characterized to be a single-molecule magnet (SMM) with fast quantum tunneling of its magnetization (QTM). The single Ni^II ion zero-field-splitting (zfs) parameters D_i [= -5.30(5) cm^-1] and E_i [= ±1.20(2) cm^-1] in the doped complex 1 were evaluatedby rotation of a crystal in three planes. The easy-axes of magnetization associated with the single-ion zfs interactionswere also found to be tilted 15 away from the crystallographic c direction. This inclination provides a possibleexplanation for the fast QTM observed for complex 2. The single-ion zfs parameters are then related to the zfsparameters for the Ni₄ molecule by irreducible tensor methods to give D = -0.69 cm^-1 for the S = 4 ground stateof the SMM, where the axial zfs interaction is given by Djournals/inocaj/44/i11/eqn/ic0482279e10001.gif">.