Preparation and Crystal Structures of 4-(4′-Pyridylthio)-1-methylpyridinium Salts: Assembly of a Donor–Acceptor-Type Molecule Containing a Sulfide Bridge
✍ Scribed by Ryo Horikoshi; Tomoyuki Mochida; Hiroshi Moriyama
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 253 KB
- Volume
- 164
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
A series of ionic 4-(4 0 -pyridylthio)-1-methylpyridinium salts with different counteranions (1, I À ; 2, BF 4 À ; 3, PF 6 À ; and 4, OTf À , where OTf=trifluoromethanesulfonate) have been prepared. Structural analysis reveals that the cation exhibits a variety of stacking structures dependent on the anion. Compound 1 crystallizes in space group P2 1/n (#14), with a= 10.764(3) A ˚, b=9.601(5) A ˚, c=13.105(3) A ˚, b=108.35(2), V= 1285.4(8) A ˚3, and Z=4. In this compound, each cation moiety is stacked in a helical arrangement along the c-axis. Compound 2, which is isomorphous to 1, has space group P2 1/n (#14), with a=11.647(2) A ˚, b=9.203(3) A ˚, c=13.232(2) A ˚, b=108.42(2), V=1345.6(5) A ˚3, and Z=4. Compound 3 crystallizes in space group P2 1/n (#14), with a=8.06(1) A ˚, b=17.43(1) A ˚, c=10.30(1) A ˚, b=103.0(1), V=1410(3) A ˚3, and Z=4. In this salt, the cation molecules assume a head-to-tail stacking arrangement, forming a polar pseudo 1-D chain. Compound 4 crystallizes in space group P 1 1 (#2), with a=7.585(4) A ˚, b= 15.443(7) A ˚, c=6.775(4) A ˚, a=99.33(4), b=108.35(2) o , c= 98.37(4), V=756.6(7) A ˚3, and Z=2. The structure of 4 consists of a columnar stacking of pyridine moieties, with the cation moieties surrounded by the counteranions. Calculations show that the 4-(4 0 -pyridylthio)-1-methylpyridinium cation may be a good building block for second harmonic generation (SHG) materials, even though salts 1-4 crystallized in centrosymmetric structures and were SHG inactive.