Definition of magneto-structural correlations for the MnII ion
Definition of magneto-structural correlations for the MnII ion
复制标题
DOI：
10.1002/chem.200800426
复制
发表时间：
2008-01-01
影响因子：
4.3
通讯作者：
Neese, Frank
中科院分区：
文献类型：
--
作者：
Duboc, Carole;Collomb, Marie-Noelle;Neese, Frank
用多频EPR谱研究了具有N6配位球的高自旋单核Mn-Ⅱ配合物[Mn（tpa）（NCS）（2）]（1）（tpa=tris-2-picolylamine），[Mn（tBu（3）-terpy）（2）]-（PF_6）（2）（2）（tBu（3）-terpy= 4，4 '，4“-三叔丁基-2，2'：6 '，2”-三联吡啶）和[Mn（terpy）（2）]（I）（2）（3）（terpy= 2，2'：6'，2”-三联吡啶）的电子性质. 1个中心点CH_3CN和2个中心点C_4 H_（10）O·0.5C（2）H（5）OH中心点0.5CH（3）OH的X射线结构表明Mn-Ⅱ离子位于畸变八面体的中心。1-3的D值都落在0.041 - 0.105 cm（-1）的窄范围内。本文报道的结果与文献中发现的结果的比较与以下观察一致：只要配位层仅涉及基于氮和/或氧的配体，D值对Mn-II离子的配位数（6或5）敏感。本文通过DFT模型计算分析了这种磁结构相关性。计算了1-3的零场分裂参数，与实验值符合较好。建立了[Mn（NH_3）（x）（OH_2）（y）]（2+）（x+y=5或6）和[Mn（NH_3）（5）X]（+）（X=OH，Cl）的简化模型，探讨了As的来源。研究表明：（1）Mn-Ⅱ离子的配位数（5或6）对D的影响很敏感;（2）在五个坐标系中，自旋-轨道耦合部分对D的贡献最大;（3）在六个坐标系中，自旋-自旋相互作用对D的贡献最大;（4）水配体的去质子化导致D的增加，与OH-对H2O的相对配位场一致。
The electronic properties of the high spin mononuclear Mn-II complexes [Mn(tpa)(NCS)(2)] (1) (tpa=tris-2-picolylamine), [Mn(tBu(3)-terpy)(2)]-(PF6)(2) (2) (tBu(3)-terpy=4,4',4 ''-tri-tert-butyl-2,2':6',2 ''-terpyridine) and [Mn(terpy)(2)](I)(2) (3) (terpy=2,2':6',2"-terpyridine) with an N6 coordination sphere have been determined by multi-frequency EPR spectroscopy. The X-ray structures of 1 center dot CH3CN and 2 center dot C4H10O.0.5C(2)H(5)OH center dot 0.5CH(3)OH reveal that the Mn-II ion lies at the center of a distorted octahedron. The D-values of 1-3 all fall in the narrow range of 0.041 to 0.105 cm(-1). The comparison of the results reported here and those found in the literature is consistent with the following observation: the D value is sensitive to the coordination number (6 or 5) of the Mn-II ion as long as the coordination sphere involves only nitrogen and/or oxygen based ligands. This magneto-structural correlation has been analyzed in this work though DFT model calculations. The zero-field splitting (zfs) parameters of 1-3 have been calculated and are in reasonable agreement with the experimental values. Hypothetical simplified models [Mn(NH3)(x)(OH2)(y)](2+) (x+y=5 or 6 and [Mn(NH3)(5)X](+) (X=OH, Cl)) have been constructed to investigate the origin of the As. This investigation reveals i)that D is sensitive to the coordination number (5 or 6) of the Mn-II ion, ii) for the five coordinate systems the major contribution to D is the spin-orbit coupling part, iii) for the six coordinate systems the major contribution to D is the spin-spin interaction and iv) the deprotonation of a water ligand leads to an increase of D, consistent with the relative ligand fields of OH- versus H2O.