Electronic and magnetic study of polycationic Mn(12) single-molecule magnets with a ground spin state S = 11.
Electronic and magnetic study of polycationic Mn(12) single-molecule magnets with a ground spin state S = 11.
复制标题
基自旋态 S = 11 的聚阳离子 Mn(12) 单分子磁体的电子和磁学研究。
DOI：
10.1021/ic901824d
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发表时间：
2010
影响因子：
4.6
通讯作者：
V. Corradini
中科院分区：
文献类型：
--
作者：
J. Clemente;E. Coronado;A. Forment‐Aliaga;A. Gaita;C. Giménez‐Saiz;F. Romero;W. Wernsdorfer;R. Biagi;V. Corradini
The preparation, magnetic characterization, and X-ray structures of two polycationic Mn(12) single-molecule magnets [Mn(12)O(12)(bet)(16)(EtOH)(4)](PF(6))(14).4CH(3)CN.H(2)O (1) and [Mn(12)O(12)(bet)(16)(EtOH)(3)(H(2)O)](PF(6))(13)(OH).6CH(3)CN.EtOH.H(2)O (2) (bet = betaine = (CH(3))(3)N(+)-CH(2)-CO(2)(-)) are reported. 1 crystallizes in the centrosymmetric P2/c space group and presents a (0:2:0:2) arrangement of the EtOH molecules in its structure. 2 crystallizes in the noncentrosymmetric P4 space group with two distinct Mn(12) polycations, [Mn(12)O(12)(bet)(16)(EtOH)(2)(H(2)O)(2)](14+) (2A) and [Mn(12)O(12)(bet)(16)(EtOH)(4)](14+) (2B) per unit cell. 2A and 2B show a (1:1:1:1) distribution of the coordinated solvent molecules. Interestingly, bond valence sum calculations extracted from X-ray diffraction data indicate the presence of two Mn(2+) ions in the Mn(12) core for both 1 and 2. This finding is confirmed by X-ray absorption spectroscopy (XAS) measurements. A complete magnetic characterization, including subkelvin micro-SQUID magnetometry and inelastic neutron scattering (INS) measurements, permits to extract the parameters of the giant spin Hamiltonian of these polycations. Compared with the archetypal Mn(12) acetate, an increase in the value of the ground spin state from S = 10 to S = 11 together with a decrease in the effective energy barrier, is observed for 1 and 2. Such a result is consistent with the reduction of two Mn(3+) to the less anisotropic Mn(2+) ion in the structures.
