Synthesis, structure and gas-phase reactivity of a silver hydride complex [Ag3{(PPh2)2CH2}3(μ3-H)(μ3-Cl)]BF4.
Synthesis, structure and gas-phase reactivity of a silver hydride complex [Ag3{(PPh2)2CH2}3(μ3-H)(μ3-Cl)]BF4.
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DOI：
10.1002/anie.201302436
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发表时间：
2013-08
影响因子：
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通讯作者：
Athanasios Zavras;George N. Khairallah;Timothy U. Connell;J. White;A. Edwards;P. Donnelly;R. O'hair
中科院分区：
文献类型：
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作者：
Athanasios Zavras;George N. Khairallah;Timothy U. Connell;J. White;A. Edwards;P. Donnelly;R. O'hair
钴金属氧化物由于其有趣的结构和物理性质以及它们在有机底物转化中作为试剂或中间体的作用而继续吸引人们的注意。例如，几种氢化铜化合物已经在结构上表征并开发为用于烯酮的1，4还原反应和用于炔的氢化铜化的催化剂。与此相反，而其较重的同源物已牵连作为氧化和其他反应的活性中间体，并已在气相中，以及通过矩阵隔离实验，以及一些银和金的氢化物化合物已被合成和结构特征的X射线晶体学。我们一直在研究硬币-金属簇合物在有机底物的C C键偶联反应、点击化学和C X键活化8]中的作用。在我们的工作中，基于质谱（MS）的方法被用来探索簇的形成和反应性，并直接凝聚相合成和表征的新簇。作为该簇化学计划的一部分，我们对通过硼氢化钠还原金盐来产生相关的银纳米团簇来扩展产生双（膦基）保护的金纳米团簇的方法产生兴趣。在此，我们报告了一个新的银氢化物簇，[Ag 3 HClL 3] +（L =双（膦基）配体），这促使其质谱定向合成和X射线和中子晶体结构表征，揭示了{Ag 3（m3-H）（m3-Cl）} +核心结构的偶然MS为基础的发现。14]该集群的气相反应性也进行了探讨。在1，1-双（三氟乙酸）存在下用硼氢化钠处理的银（I）[Ag（tfa）]的甲醇/氯仿溶液的电喷雾电离质谱（ESI-MS）分析二苯基膦甲烷（以下称为L）显示出形成银氢化物簇阳离子的证据（图1;另见支持信息，图S1），根据同位素模式，（图S2和S3）和高分辨率精确质量测量（表S1），公式为：[Ag 3 HL 3]、[Ag 3 HClL 3]、[Ag 3Cl 2L 3] +和[Ag 10 H8 L 6]。在记录的任何光谱中均未观察到[Ag 3 H2 L3] +物质。用硼氘化钠代替NaBH 4证实NaBH 4是簇中氢化物的来源（例如，形成[Ag 3DL 3] 2+而不是[Ag 3 HL 3] ;图S4和S5）。通过ESI-MS观察到丰富的银氢化物簇合物阳离子，鼓励我们改进凝聚相合成路线（支持信息，方法A），以分离出适合通过IR和1H NMR光谱法表征的结晶盐（图S6和S7，以及支持文本），以及通过单晶X射线衍射和中子衍射进行结构测定。三氟乙酸根（tfa）阴离子[Ag_3 H（tfa）L_3]~+配位的三核银氢化物簇的存在
Coinage metal hydrides continue to attract attention because of their interesting structural and physical properties, as well as for their role as reagents or intermediates in the transformation of organic substrates. For example, several copper hydride compounds have been structurally characterized and developed as catalysts for 1,4 reduction reactions of enones and for hydrocupration of alkynes. In contrast, whereas their heavier congeners have been implicated as reactive intermediates in oxidation and other reactions, and have been characterized in the gas phase, as well as by matrix isolation experiments, few silver and gold hydride compounds have been synthesized and structurally characterized by X-ray crystallography. We have been examining the role of coinage-metal cluster compounds in C C bond coupling reactions, click chemistry, and C X bond activation 8] of organic substrates. In our work, methods based on mass spectrometry (MS) are employed to explore cluster formation and reactivity, and to direct condensed phase synthesis and characterization of novel clusters. As part of this cluster chemistry program, we became interested in extending the method of generating bis(phosphino)-protected gold nanoclusters by sodium borohydride reduction of gold salts to generate related silver nanoclusters. Herein, we report on the serendipitous MSbased discovery of a novel silver hydride cluster, [Ag3HClL3] + (L = bis(phosphino) ligand), which has prompted its massspectrometry-directed synthesis and X-ray and neutron crystallographic structural characterization, which reveal a {Ag3(m3-H)(m3-Cl)} + core structure. 14] The gas-phase reactivity of this cluster is also explored. Electrospray ionization mass spectrometry (ESI-MS) analysis of methanol/chloroform solutions of silver(I) trifluoroacetate [Ag(tfa)] that had been treated with sodium borohydride in the presence of 1,1-bis(diphenylphosphino)methane (designated hereafter as L) showed evidence of the formation of silver hydride cluster cations (Figure 1; see also the Supporting Information, Figure S1), which, based on isotope patterns (Figures S2 and S3) and high resolution accurate mass measurements (Table S1), are formulated as: [Ag3HL3] , [Ag3HClL3] , [Ag3Cl2L3] + and [Ag10H8L6] . The species [Ag3H2L3] + was not observed in any of the spectra recorded. Replacing NaBH4 with sodium borodeuteride confirmed that NaBH4 is the source of the hydride in the clusters (for example, formation of [Ag3DL3] 2+ and not [Ag3HL3] ; Figures S4 and S5). The observation of abundant silver hydride cluster cations by ESI-MS encouraged us to refine the condensed-phase synthetic route (Supporting Information, Method A) to allow the isolation of a crystalline salt suitable for characterization by IR and H NMR spectroscopy (Figures S6 and S7, as well as supporting text), as well as structural determination by single-crystal X-ray diffraction and neutron diffraction. The presence of the abundant trinuclear silver hydride cluster ligated by the trifluoroacetate (tfa) anion, [Ag3H(tfa)L3] +