English  |  正體中文  |  简体中文  |  Items with full text/Total items : 49378/84106 (59%)
Visitors : 7363526      Online Users : 61
RC Version 7.0 © Powered By DSPACE, MIT. Enhanced by NTU Library & TKU Library IR team.
Scope Tips:
  • please add "double quotation mark" for query phrases to get precise results
  • please goto advance search for comprehansive author search
  • Adv. Search
    HomeLoginUploadHelpAboutAdminister Goto mobile version
    Please use this identifier to cite or link to this item: http://tkuir.lib.tku.edu.tw:8080/dspace/handle/987654321/25149


    Title: Preparative, structural, and electrical studies of the 1 : 1 and 2 : 3 tetracyanoquinodimethane salts of 4,4-bithiopyranylidene (BTP)
    Authors: 李榮熹;Lee, Jung-si;Sandman, Daniel J.;Epstein, Arthur J.;Holmes, Timothy J.;Titus, Donald D.
    Contributors: 淡江大學化學學系
    Date: 1980
    Issue Date: 2009-12-01
    Publisher: Cambridge: Royal Society of Chemistry (RSC)
    Abstract: The preparation, single crystal growth, and single crystal conductivity of the 1 : 1 and 2 : 3 7,7,8,8-tetracyanoquinodimethane (TCNQ) salts of 4,4′-bithiopyranylidene are reported. The crystal structure of the 2 : 3 salt, the first structure of a 2 : 3 TCNQ salt from a neutral planar closed-shell donor, has been determined by X-ray diffraction at room temperature. (BTP)2(TCNQ)3 crystallizes in the triclinic space group P, a= 8.351(5), b= 17.445(4), c= 8.020(4), α= 97.35(3), β= 103.10(4), γ= 88.15(4), U= 1 128.6(8)Å3, Z= 1, Dcalc.= 1.467 g cm–3, Dobs.= 1.46(1) g cm–3. The structure was solved by Patterson and Fourier methods to a final R of 0.046 for 1 490 unique reflections with F0 > 3σ(F0). (BTP)2(TCNQ)3 has a mixed stack crystal structure which alternates a pair of BTP cation-radicals and three TCNQ molecular species. There are two crystallographically distinct types of TCNQ : a centrosymmetric (c-TCNQ) and a non-centrosymmetric (n-TCNQ) form in the ratio 1 : 2. The bond lengths of centrosymmetric TCNQ closely resemble those of neutral TCNQ while those of non-centrosymmetric TCNQ are similar to those of TCNQ–1, a situation found in other 2 : 3 TCNQ salts. The bridging double bond of the BTP cation-radical is quite long, 1.429(6)Å, ca. 0.05 Å longer than that of a neutral BTP derivative. As found in the 1 : 1 heterafulvalene–TCNQ segregated stack conductors, there are short contact distances between the sulphur atoms on the BTP cation and the cyano nitrogens on TCNQ. However, in the present structure this mode of interaction is qualitatively different in that each BTP sulphur atoms contacts (‘plugs into’) two cyano groups, while in the heterafulvalene–TCNQ salts, each chalcogen contacts only one cyano nitrogen. While BTP is iso-π-electronic to tetrathiafulvalene (TTF), which interacts with TCNQ to give a metallic 1 : 1 salt, BTP–TCNQ is a semiconductor with a room temperature conductivity (σ) of 30 ohm–1 cm–1. The temperature dependence of σ for BTP–TCNQ between room temperature and 80 K is well described by σ(T)=AT–αexp(–Δ/T), an expression representing the product of an activated charge carrier concentration with a system specific activation energy, Δ and a temperature dependent mobility, with α 2.64 and Δ 1 480 K (0.13 eV). As expected from its mixed stack crystal structure, (BTP)2(TCNQ)3 is a semiconductor with a room temperature single crystal conductivity of 0.10, ohm–1 cm–1 and an activation energy of 0.16 and 0.18 eV measured from conductivity and thermoelectric power respectively.
    Relation: Journal of the chemical society : Perkin Transactions II 11, pp.1578-1585
    DOI: 10.1039/P29800001578
    Appears in Collections:[化學學系暨研究所] 期刊論文

    Files in This Item:

    There are no files associated with this item.

    All items in 機構典藏 are protected by copyright, with all rights reserved.


    DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library & TKU Library IR teams. Copyright ©   - Feedback