提高氰基桥联单分子磁体中的自旋反转势垒：包含[(5-溴水杨醛)锰](+)单元的线性Mn(III)₂M(III)(CN)₆（M = Cr、Fe）物种。

Raising the spin-reversal barrier in cyano-bridged single-molecule magnets: linear Mn(III)(2)M(III)(CN)(6) (M = Cr, Fe) species incorporating [(5-Brsalen)Mn](+) units.

作者信息

Choi Hye Jin, Sokol Jennifer J, Long Jeffrey R

机构信息

Department of Chemistry, University of California, Berkeley, California 94720, USA.

出版信息

Inorg Chem. 2004 Mar 8;43(5):1606-8. doi: 10.1021/ic035327q.

DOI:10.1021/ic035327q

PMID:14989652

Abstract

Reactions between K(3)[M(CN)(6)] and Mn(5-Brsalen)(H(2)O)(2) (5-Brsalen = N,N'-ethylenebis(5-bromosalicylidene)aminato dianion) in a mixture of methanol and water afford the compounds K[(5-Brsalen)(2)(H(2)O)(2)Mn(2)M(CN)(6)].2H(2)O, with M = Cr (1) or Fe (2). The two compounds are isostructural, each containing a molecular cluster with a linear Mn(III)-NC-M(III)-CN-Mn(III) core and tetragonally elongated coordination about the Mn(III) centers. Magnetic data indicate the presence of weak exchange interactions within the clusters, giving rise to ground states of S = (5)/(2) and (9)/(2) with significant zero-field splitting. Despite the proximity of spin-excited states, ac susceptibility data reveal frequency-dependent out-of-phase signals characteristic of single-molecule magnets with spin-reversal barriers of U(eff) = 16 and 25 cm(-)(1), respectively.

摘要

在甲醇和水的混合溶液中，K(3)[M(CN)(6)]与Mn(5-Brsalen)(H(2)O)(2)（5-Brsalen = N,N'-亚乙基双(5-溴水杨醛)氨基二价阴离子）反应生成化合物K[(5-Brsalen)(2)(H(2)O)(2)Mn(2)M(CN)(6)].2H(2)O，其中M = Cr (1) 或Fe (2)。这两种化合物具有相同的结构，每个都包含一个分子簇，其核心为线性的Mn(III)-NC-M(III)-CN-Mn(III)，并且Mn(III)中心周围的配位呈四方伸长。磁性数据表明簇内存在弱交换相互作用，导致基态分别为S = (5)/(2) 和 (9)/(2)，且具有显著的零场分裂。尽管自旋激发态接近，但交流磁化率数据显示出频率依赖性的异相信号，这是单分子磁体的特征，其自旋反转势垒分别为U(eff) = 16 和 25 cm(-)(1)。