Silver Alkynyl-Phosphine Clusters: An Electronic Effect of the Alkynes Defines Structural Diversity

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• 作者：Yi-Ting Chen ; Ilya S. Krytchankou ; Antti J. Karttunen ; Elena V. GrachovaSergey P. Tunik ; Pi-Tai Chou ; Igor O. Koshevoy
• 刊名：Organometallics
• 出版年：2017
• 出版时间：January 23, 2017
• 年：2017
• 卷：36
• 期：2
• 页码：480-489
• 全文大小：668K
• ISSN：1520-6041

文摘

The face-capping triphosphine, 1,1,1-tris(diphenylphosphino)methane (tppm), together with bridging alkynyl ligands and the counterions, facilitates the formation of a family of silver complexes, which adopt cluster frameworks of variable nuclearity. The hexanuclear compounds [Ag₆(C₂C₆H₄-4-X)₃(tppm)₂(An^–)₃] (X = H (1), CF₃ (2), OMe (3), An^– = CF₃SO₃^–; X = OMe (4), An^– = CF₃COO^–) are produced for the electron-accepting to moderately electron-donating alkynes and the appropriate stoichiometry of the reagents. 1 and 3 undergo an expansion of the metal core when treated with 1 equiv of Ag⁺ to give the species [Ag₇(C₂C₆H₄-4-X)₃(tppm)₂(CF₃SO₃)₃](CF₃SO₃) (X = H (5), OMe (6)). The electron-donating substituent (X = NMe₂) particularly favors this Ag₇ arrangement (7) that undergoes geometry changes upon alkynylation, resulting in the capped prismatic cluster [Ag₇(C₂C₆H₄-4-NMe₂)₄(tppm)₂(CF₃SO₃)](CF₃SO₃)₂ (8). Alternatively, for the aliphatic ^tBu-alkyne, only the octanuclear complex [Ag₈(C₂Bu^t)₄{(PPh₂)₃CH}₂(CF₃SO₃)₂](CF₃SO₃)₂ (9) is observed. The structures of 1–4 and 6–9 were determined by X-ray diffraction analysis. In solution, all the studied compounds were found to be stereochemically nonrigid that prevented their investigation in the fluid medium. In the solid state, clusters 2, 3, 5–8 exhibit room temperature luminescence of triplet origin (maximum Φ_em = 27%, λ_em = 485–725 nm). The observed emission is assigned mainly to [d(Ag) → π*(alkyne)] electronic transitions on the basis of TD-DFT computational analysis.