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首页> 外文期刊>Chemistry: A European journal >Silver—Ethene Complexes [Ag(η~2- C_2H_4)_n][Al(OR~F)_4] withn=1,2, 3 = Fluorine-Substituted Group)
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Silver—Ethene Complexes [Ag(η~2- C_2H_4)_n][Al(OR~F)_4] withn=1,2, 3 = Fluorine-Substituted Group)

机译：银-乙烯络合物[Ag（η〜2- C_2H_4）_n] [Al（OR〜F）_4]，n = 1,2，3 =氟取代的基团

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摘要

Compounds including thefree or coordinated gas-phase cations[Ag(η~2-C_2H_4)_n]~+(n=1-3)were stabi-lized with very weakly coordinatinganions [A]- (A = Al{OC(CH_3)(CF_3)_2}_4,n=1 (1); Al{OC(H)(CF_3)_2}_4,n=2 (3);Al(OC(CF_3)_3}_4,n=3(5);{(F_3C)_3CO}_3Al-F-Al{OC(CF_3)_3}_3,n=3(6)). They were prepared by reactionof the respective silver(I) salts with sto-ichiometric amounts of ethene inCH_2Cl_2solution. As a reference wealso prepared the isobutene complex[(Me_2C=CH-2)Ag(Al{OC(CH_3)-(CF_3)_2}_4)](2). The compounds werecharacterized by multinuclear solution-NMR, solid-state MAS-NMR, IR andRaman spectroscopy as well as by theirsingle crystal X-ray structures. MAS-NMR spectroscopy shows that the [Ag-(η~2-C_2H_4)_3]~+cation in its [Al{OC-(CF_3)_3}_4]~-salt exhibits time-averaged D_(3h)-symmetry and freely rotatesaround its principal z-axis in the solid state. All routine X-ray structures(2θmax<55°) converged within the 3alimit at C=C double bond lengths thatwere shorter or similar to that of freeethene. In contrast, the respectiveRaman active C=C stretching modesindicated red-shifts of 38 to 45 cm~(-1),suggesting a slight C=C bond elonga-tion. This mismatch is owed to residuallibrational motion at 100 K, the tem-perature of the data collection, as wellas the lack of high angular data owingto the anisotropic electron distributionin the ethene molecule. Therefore, amethod for the extraction of the C=Cdistance in [M(C_2H_4)] complexes fromexperimental Raman data was devel-oped and meaningful C=C distances were obtained. These spectroscopic C=C distances compare well to newly col-lected X-ray data obtained at high res-olution (2θ_(max)=100°) and low temper-ature (100 K). To complement the ex-perimental data as well as to obtainfurther insight into bond formation, thecomplexes with up to three ligandswere studied theoretically. The calcula-tions were performed with DFT (BP86/TZVPP, PBEO/TZVPP), MP2/TZVPPand partly CCSD(T)/AUG-cc-pVTZmethods. In most cases several isomerswere considered. Additionally, [M-(C_2H_4)_3] (M= Cu~+, Ag~+,Au~+, Ni~0, Pd~Pt~0, Na~+) were investigated with AIMtheory to substantiate the preferencefor a planar conformation and to esti-mate the importance of a donation andπ back donation. Comparing the group10 and 11 analogues, we find that thelack of π back bonding in the group 11cations is almost compensated by in-creased σ donation.
机译：包含游离或配位气相阳离子[Ag（η〜2-C_2H_4）_n]〜+（n = 1-3）的化合物用非常弱的配位阴离子[A]-（A = Al {OC（CH_3） （CF_3）_2} _4，n = 1（1）; Al {OC（H）（CF_3）_2} _4，n = 2（3）; Al（OC（CF_3）_3} _4，n = 3（5） ; {（F_3C）_3CO} _3Al-F-Al {OC（CF_3）_3} _3，n = 3（6））。它们是通过将各自的银（I）盐与化学计量的乙烯在CH_2Cl_2溶液中反应制备的。作为参考，我们还制备了异丁烯配合物[（Me_2C = CH-2）Ag（Al {OC（CH_3）-（CF_3）_2} _4）]（2）。化合物通过多核溶液-NMR，固态MAS表征-NMR，IR和拉曼光谱，以及它们的单晶X射线结构; MAS-NMR光谱显示，其[Al {OC-（CF_3）_3]中的[Ag-（η〜2-C_2H_4）_3]〜+阳离子} _4]〜-盐表现出时间平均的D_（3h）对称性，并在固态时绕其主z轴自由旋转，所有常规X射线结构（2θmax<55°）都在C = C两倍的3alimit内会聚键长度较短或与fre相似乙烯。相反，相应的拉曼活性C ＝ C拉伸模式表明红移为38至45cm 2-（-1），这表明C ＝ C键的延伸很小。这种失配归因于在100 K时的残余自由运动，数据收集的温度，以及由于乙烯分子中的各向异性电子分布而缺乏高角度数据。因此，开发了一种从实验拉曼数据中提取[M（C_2H_4）]配合物中C = C距离的方法，并获得了有意义的C = C距离。这些光谱的C = C距离与在高分辨率（2θ_（max）= 100°）和低温（100 K）下获得的新收集的X射线数据相比较。为了补充实验数据并进一步了解键的形成，理论上研究了具有多达三个配体的配合物。使用DFT（BP86 / TZVPP，PBEO / TZVPP），MP2 / TZVPP和部分CCSD（T）/ AUG-cc-pVTZ方法进行计算。在大多数情况下，考虑了几种异构体。另外，用AIM理论研究了[M-（C_2H_4）_3]（M = Cu〜+，Ag〜+，Au〜+，Ni〜0，Pd〜Pt〜0，Na〜+），以证实对平面构象的偏爱。并估算捐赠和返还捐赠的重要性。比较第10组和第11组类似物，我们发现第11组阳离子中π背键的缺乏几乎可以通过增加的σ捐款来弥补。

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