Synthesis and characterization of a two-coordinate manganese complex and its reaction with molecular hydrogen at room temperature.-猫眼课题宝

DOI：

10.1002/anie.201304642

发表时间：

2013-11

期刊：

Angewandte Chemie

影响因子：

通讯作者：

中科院分区：

文献类型：

作者：

Prinson P. Samuel;K. Mondal;H. Roesky;Markus R. Hermann;G. Frenking;S. Demeshko;F. Meyer;A. Stückl;J. Christian;N. Dalal;L. Ungur;L. Chibotaru;K. Pröpper;A. Meents;B. Dittrich

2005年，我们报道了第一个用钠钾合金还原氯化锰得到的化合物(L=CH(CMeNAr)2，Ar=2，6-iPr2C6H3)。得到的化合物包含两个三配位的锰原子。[1]我们很好奇当锰原子的配位数进一步减少时，化合物的电子、磁性和化学性质。我们最近成功地用环烷基(氨基)卡宾(CAACD)在两配位环境中稳定了一个硅原子，这促使我们遵循类似的合成策略，以制备一个具有两配位锰原子的化合物。[2]这种双配位过渡金属非常罕见，在配位化学中研究得很少。这些物种与双配位过渡金属的不稳定的主要原因是分子间的缔合以满足配位要求。[3]近年来，化学家们通过使用大体积配体来克服这一困难。寻找这类配位不饱和过渡金属络合物的主要原因是它们有趣的磁性特征。[4]除了独特的磁性行为外，在配位不饱和位置发生难以捉摸的化学反应的巨大可能性使化学家们对两个配位金属中心感兴趣。到目前为止，在气相和固相中只有少数具有两配位锰中心的化合物已知，而具有线形构型的配合物相当少见。[5]已报道的在固相中具有两配位锰原子和线形构型的化合物只有Mn[C(SiMe3)3]2和Mn-[Sar]2，(Ar=C6H3-2，6(C6H2-2，4，6-iPr3)2)。[5a-c]所有报道的两配位锰离子的配合物都是高自旋构型，S=5/2自旋态，磁矩在5.1-6.0μB范围内。本文报道了一种化合物(CaAc)2Mn(2)，具有两配位的锰原子和线形构型，磁矩为4.15μB，反映了总的自旋基态ST=3/2。此外，我们还报道了分子氢在2的自由基中心的容易分裂。(CaAc：)MnCl2(1)在四氢呋喃中以1：1的比例在室温下反应得到(CaAc：)MnCl2(1)。1与KC8和CAAc：按1：2.1：1的比例反应，得到深紫色的产物(图式1)。2的X射线结构显示出C-Mn-C=1808的线性几何结构(图1)。Mn±C键间距为1.9655(14)，明显短于相应的键长度

In 2005 we reported the first LMnÀMnL compound (L= CH (CMeNAr) 2, Ar= 2, 6-iPr2C6H3) obtained by the reduction of LMnCl with sodium–potassium alloy. The resulting compound contains two three-coordinate Mn atoms.[1] We were curious about the electronic, magnetic, and chemical properties of the compound when the coordination number at the manganese atom is further reduced. Our recent success in stabilizing a silicon atom in a two-coordinate environment using cyclic alkyl (amino) carbene (cAACD) encouraged us to follow a similar synthetic strategy in order to prepare a compound with a two-coordinate manganese atom.[2] Such two-coordinate transition metals are very rare and only little studied in coordination chemistry. The main reason for the instability of these species with two-coordinate transition metals is the intermolecular association to satisfy the coordination requirements.[3] In recent years, chemists have made strong efforts to overcome this difficulty by using bulky ligands. The search for such coordinatively unsaturated transition-metal complexes has been driven mainly by their interesting magnetic features.[4] In addition to the unique magnetic behavior, enormous possibilities for elusive chemical reactions at a coordinatively unsaturated site make twocoordinate metal centers interesting for chemists. So far, only a few compounds with a two-coordinate manganese center are known in the gaseous and solid phase, and complexes with linear geometry are rather uncommon.[5] The only reported complexes with two-coordinate manganese atoms and linear geometry in the solid phase are Mn [C (SiMe3) 3] 2 and Mn-[SAr] 2,(Ar= C6H3-2, 6 (C6H2-2, 4, 6-iPr3) 2). The latter compound exhibits secondary metal–ligand interactions.[5a–c] All the reported complexes with two-coordinate manganese ions are in their high-spin configuration with an S= 5/2 spin state and exhibit magnetic moments in the range of 5.1–6.0 μB. Herein we report a compound of composition (cAAC) 2Mn (2) with a two-coordinate manganese atom and linear geometry, and with a magnetic moment of 4.15 μB, which reflects a total spin ground state of ST= 3/2. In addition, we also report the facile splitting of molecular hydrogen at the radical centers of 2, resulting in the formation of (cAACH) 2Mn (3) which shows an S= 5/2 spin state because of the quenching of the radical nature of the carbene ligand.(cAAC:) MnCl2 (1) was obtained by reacting cAAC: and MnCl2 in a 1: 1 ratio in THF at room temperature. The reaction of 1 with KC8 and cAAC: in a 1: 2.1: 1 ratio afforded 2 as a deep-purple-colored product (Scheme1). The X-ray structure of 2 shows a linear geometry with C-Mn-C= 1808 (Figure 1). The MnÀC bond distance is 1.9655 (14), which is distinctly shorter than the corresponding bond length in

Synthesis and characterization of a two-coordinate manganese complex and its reaction with molecular hydrogen at room temperature.

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