Magnetic and Optical Studies on an S = 6 Ground-State Cluster [Cr12O9(OH)3(O2CCMe3)15]: Determination of, and the Relationship
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- 作者：David Collison ; Mark Murrie ; Vasily S. Oganesyan ; Stergios Piligkos ; Nigel R. J. Poolton ; Gopalan Rajaraman ; Graham M. Smith ; Andrew J. Thomson ; Grigore A. Timko ; Wolfgang Wernsdorfer ; Richard E. P. W
- 刊名：Inorganic Chemistry
- 出版年：2003
- 出版时间：August 25, 2003
- 年：2003
- 卷：42
- 期：17
- 页码：5293 - 5303
- 全文大小：202K
- 年卷期：v.42,no.17(August 25, 2003)
- ISSN：1520-510X
文摘
The dodecametallic Cr(III) cluster [Cr12O9(OH)3(O2CCMe3)15] has a ground spin state of S = 6 characterized by thespin Hamiltonian parameters gZZ = 1.965, gXX = gYY = 1.960, DS=6 = +0.088 cm-1, and ES=6 = 0 (where D andE are the axial and rhombic zero-field splitting parameters, respectively) as determined by multifrequency EPRspectroscopy and magnetization studies. Micro-SQUID magnetization studies reveal steps due to the fine structureof the ground state, with the spacing between the steps in excellent agreement with the DS=6 value determined byEPR. Analysis of high-resolution optical data (MCD) allows us to determine the single-ion g values and D value(= -1.035 cm-1) of the constituent Cr(III) ions directly. A vector coupling analysis demonstrates that the clusterZFS is almost entirely due to the single-ion component. Thus, the relative orientations of the local and clustermagnetic axes can lead to a cluster ZFS of opposite sign to the single-ion value, even when this is the onlysignificant contribution.