Aggregation of [Au(CN)4]鈭?/sup> Anions: Examination by Crystallography and 15N CP-MAS NMR and the Structural Factors Influencing Intermolecular Au路路路N Interactions

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• 作者：Andrew R. Geisheimer ; John E. C. Wren ; Vladimir K. Michaelis ; Masayuki Kobayashi ; Ken Sakai ; Scott Kroeker ; Daniel B. Leznoff
• 刊名：Inorganic Chemistry
• 出版年：2011
• 出版时间：February 21, 2011
• 年：2011
• 卷：50
• 期：4
• 页码：1265-1274
• 全文大小：1051K
• 年卷期：v.50,no.4(February 21, 2011)
• ISSN：1520-510X

文摘

To investigate the factors influencing the formation of intermolecular Au路路路NC interactions between [Au(CN)₄]^{鈭?/sup> units, a series of [cation]n+[Au(CN)₄]_n double salts was synthesized, structurally characterized and probed by IR and 15N{1H} CP-MAS NMR spectroscopy. Thus, [nBu₄N][Au(CN)₄], [AsPh₄][Au(CN)₄], [N(PPh₃)₂][Au(CN)₄], [Co(1,10-phenanthroline)₃][Au(CN)₄]₂, and [Mn(2,2鈥?6鈥?2鈥测€?terpyridine)₂][Au(CN)₄]₂ show [Au(CN)₄]鈭?/sup> anions that are well-separated from one another; no Au鈭扐u or Au路路路NC interactions are present. trans-[Co(1,2-diaminoethane)₂Cl₂][Au(CN)₄] forms a supramolecular structure, where trans-[Co(en)₂Cl₂]+ and [Au(CN)₄]鈭?/sup> ions are found in separate layers connected by Au鈭扖N路路路H鈭扤 hydrogen-bonding; weak Au路路路NC coordinate bonds complete octahedral Au(III) centers, and support a 2-D (4,4) network motif of [Au(CN)₄]鈭?/sup>-units. A similar structure-type is formed by [Co(NH₃)₆][Au(CN)₄]₃路(H₂O)₄. In [Ni(1,2-diaminoethane)₃][Au(CN)₄]₂, intermolecular Au路路路NC interactions facilitate formation of 1-D chains of [Au(CN)₄]鈭?/sup> anions in the supramolecular structure, which are separated from one another by [Ni(en)₃]2+ cations. In [1,4-diazabicyclo[2.2.2]octane-H][Au(CN)₄], the monoprotonated amine cation forms a hydrogen-bond to the [Au(CN)₄]鈭?/sup> unit on one side, while coordinating to the axial sites of the gold(III) center through the unprotonated amine on the other, thereby generating a 2-D (4,4) net of cations and anions; an additional, uncoordinated [Au(CN)₄]鈭?/sup>-unit lies in the central space of each grid. This body of structural data indicates that cations with hydrogen-bonding groups can induce intermolecular Au路路路NC interactions, while the cationic charge, shape, size, and aromaticity have little effect. While the 谓_CN values are poor indicators of the presence or absence of N-cyano bridging between [Au(CN)₄]鈭?/sup>-units (partly because of the very low intensity of the observed bands), 15N{1H} CP-MAS NMR reveals well-defined, ordered cyanide groups in the six diamagnetic compounds with chemical shifts between 250 and 275 ppm; the resonances between 260 and 275 ppm can be assigned to C-bound terminal ligands, while those subject to CN路路路H鈭扤 bonding resonate lower, around 250鈭?57 ppm. The 15N chemical shift also correlates with the intermolecular Au路路路N distances: the shortest Au鈭扤 distances also shift the 15N peak to lower frequency. This provides a real, spectroscopically measurable electronic effect associated with the crystallographic observation of intermolecular Au路路路NC interactions, thereby lending support for their viability.}