Formation of Infinite Linear Mercury Metal Chains Assisted by Face-to-Face π−π (Aryl−Aryl) Stacking Interactions

详细信息    查看全文

• 作者：Jing-Yun Wu ; Hung-Yu Hsu ; Chun-Chieh Chan ; Yuh-Sheng Wen ; Chiitang Tsai ; Kuang-Lieh Lu
• 刊名：Crystal Growth & Design
• 出版年：2009
• 出版时间：January 7, 2009
• 年：2009
• 卷：9
• 期：1
• 页码：258-262
• 全文大小：316K
• 年卷期：v.9,no.1(January 7, 2009)
• ISSN：1528-7505

文摘

Polymeric mercury compounds, [HgCl₂(bpym)]_n (1, bpym = 5,5′-bipyrimidine), [Hg₂Br₄(bpym)]_n (2), and [HgX₂(bpyz)]_n (3-Cl, X = Cl; 3-Br, X = Br; bpyz = 2,2′-bipyrazine), which are composed of linear mercury chains were assembled from HgX₂ (X = Cl, Br) and either 5,5′-bipyrimidine or 2,2′-bipyrazine at ambient temperature. Single-crystal X-ray diffraction analysis revealed that 1 presents a two-dimensional layer structure involved with one-dimensional linear mercury chains at a mercurophilic distance of 3.77 Å. It is linked by bridging chlorides and stabilized by weak, slipped face-to-face π−π (aryl−aryl) interactions between the coordinated bpym ligands. These layers are interdigitated-stacked into a three-dimensional supramolecular architecture through C−H···N and C−H···Cl−Hg hydrogen bonding interactions. Compound 2 has a two-dimensional (4,4) layer structure comprised of four-connected bpym nodes and linear Br−Hg−Br linkers. The layers are stagger-stacked in a three-dimensional supramolecular network, thereby forming zigzag mercury chains with a Hg···Hg separation of 3.94 Å and a Hg···Hg···Hg angle of 110°. Compounds 3-Cl and 3-Br are isostructural and supported by powder X-ray diffraction (PXRD) data. Crystallographical analysis showed that compound 3-Br adopts a two-dimensional (4,4) layer architecture with linear mercury chains comprised of two types of interlaced Hg(bpyz) and HgBr₂ chains. Within the linear mercury chains, the Hg atoms separate at a long distance of 4.01 Å. The bpyz ligand is bridged to two Hg^II centers with its two exo-N-donors in an anti-conformation and has a dihedral angle of 0° between the two hinged pyrazine rings. It is interesting to note that halide alone is not sufficient to induce linearity and face-to-face π−π (aryl−aryl) interactions between the coordinated organic ligands are the primary influence in the formation of linear mercury chains in 1, 3-Cl, and 3-Br.