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• 作者：Jan Dreiser ; Kasper S. Pedersen ; Torben Birk ; Magnus Schau-Magnussen ; Cinthia Piamonteze ; Stefano Rusponi ; Thomas Weyherm眉ller ; Harald Brune ; Frithjof Nolting ; Jesper Bendix
• 刊名：The Journal of Physical Chemistry A
• 出版年：2012
• 出版时间：August 2, 2012
• 年：2012
• 卷：116
• 期：30
• 页码：7842-7847
• 全文大小：340K
• 年卷期：v.116,no.30(August 2, 2012)
• ISSN：1520-5215

文摘

An isostructural series of dinuclear chromium(III)鈥搇anthanide(III) clusters is formed by fluoride abstraction of cis-[CrF₂(phen)₂]⁺ by Ln³⁺ resulting in LnF₃ and methoxide-bridged Cr鈥揕n clusters (Ln = Nd (1), Tb (2), Dy (3)) of formula [Cr^III(phen)₂(渭-MeO)₂Ln(NO₃)₄]路xMeOH (x = 2鈥?.73). In contrast to fluoride, methoxide bridges in a nonlinear fashion, which facilitates chelation. For 3, X-ray magnetic circular dichroism (XMCD) provides element-specific magnetization curves that are compared to cluster magnetization and susceptibility data acquired by SQUID magnetometry. The combination of XMCD and SQUID is able to resolve very small magnetic coupling values and reveals a weak Cr^III鈥揇y^III coupling of j = 鈭?.04(3) cm^鈥?. The Dy^III ion has a ground-state Kramers doublet of m_J = 卤13/2, and the first excited doublet is found to be m_J = 卤11/2 at an energy of 未 = 57(21) cm^鈥?. The Cr^III ion exhibits a uniaxial anisotropy of D_Cr = 鈭?.7(1.0) cm^鈥?. Further, we observe that a weak anisotropic coupling of dipolar origin is sufficient to model the data, suggesting that methoxide bridges do not play a significant role in the magnetic coupling for the present systems.