Syntheses, Crystal Structures and Adsorption Properties of Ultramicroporous Coordination Polymers Constructed from Hexafluorosilicate Ions and Pyrazine

✍ Scribed by Kazuhiro Uemura; Akihisa Maeda; Tapas Kumar Maji; Prakash Kanoo; Hidetoshi Kita

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 773 KB
• Volume: 2009
• Category: Article
• ISSN: 1434-1948
• DOI: 10.1002/ejic.200900144

✦ Synopsis

Abstract

Three novel coordination polymers based on M^2+^ (M = Cu, Zn), pyrazine (pyz) and the SiF~6~^2–^ ion, [Cu(SiF~6~)(pyz)(H~2~O)~2~]~n~ (1a), {[Cu(SiF~6~)(pyz)~3~]·2H~2~O}~n~ (1b blabla 2H~2~O) and {[Zn(SiF~6~)(pyz)~2~]·2MeOH}~n~ (2 blabla 2MeOH), have been synthesized and characterized by single‐crystal X‐ray diffraction analyses. Compound 1a forms straight one‐dimensional chains of–Cu(OH~2~)~2~–pyz–, which are bridged by SiF~6~^2–^ ions to produce two‐dimensional sheets. Compound 1b blabla 2H~2~O forms straight two‐dimensional sheets of –Cu(pyz)~2~–pyz– chains bridged by SiF~6~^2–^ ions, where perpendicularly protruding pyz planes are stacked to produce a three‐dimensional framework with 2.5 × 2.2 Å^2^ pores. In compound 2 blabla 2MeOH, grids of [Zn(pyz)~2~]~n~ are bridged by SiF~6~^2–^ ions axially coordinating to Zn^2+^ ions to produce an open three‐dimensional framework. The 4.5 × 4.5 Å^2^ pores in 2 blabla 2MeOH are surrounded by pyz panels, and they remain intact after removal of solvents to give [Zn(SiF~6~)(pyz)~2~]~n~ (2). The permanent porosity of 2 was characterized by adsorption studies with solvent vapours such as MeOH (kinetic diameter 3.8 Å), EtOH (4.3 Å), __i__PrOH (4.7 Å) and Me~2~CO (4.7 Å), showing a size‐exclusive effect at around 4.7 Å. Furthermore, the H~2~ adsorption/desorption isotherm of 2 at 77 K shows a sharp uptake with a slight hysteresis loop, which is attributed to both the small size of the pore and the interaction between H~2~ molecules and fluorine (SiF~6~^2–^) atoms that are exposed on the pore surfaces. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)