ChemInform Abstract: A NEW CLASS OF HIGHLY CONDUCTING ORGANIC MATERIALS: CHARGE‐TRANSFER SALTS OF THE TETRATHIAFULVALENES WITH THE TETRAHALO‐P‐BENZOQUINONES
ChemInform Abstract: A NEW CLASS OF HIGHLY CONDUCTING ORGANIC MATERIALS: CHARGE‐TRANSFER SALTS OF THE TETRATHIAFULVALENES WITH THE TETRAHALO‐P‐BENZOQUINONES
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ChemInform 摘要：一类新的高导电有机材料：四硫富瓦烯与四卤代对苯醌的电荷转移盐
DOI：
10.1021/ja00510a061
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发表时间：
1979
期刊：
影响因子：
--
通讯作者：
K. Bechgaard
中科院分区：
文献类型：
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作者：
J. Torrance;J. Mayerle;V. Lee;K. Bechgaard
III x4BQ X= F, Cl, Br, 1，其中供体和受体分子交替。我们所采用的方法是试图抑制良好的供体-受体轨道重叠，从而最小化稳定这种混合堆栈的穆利肯电荷转移相互作用，并认为分离堆栈可能在默认情况下形成。产生不利的供体-受体重叠的一种方法是选择一对分子，使相关的前沿轨道（供体的HOMO轨道和受体-受体的LUMO轨道，如图所示（方案一）分子I， II和III）在反转方面具有不同的对称性。为了满足部分电荷转移的标准，我们使用了2-3个电化学半波电位作为供体电离电位和受体电子亲和力的相对度量。这些值，结合静电晶体结合能的考虑，可以作为选择分子的粗略指南3，使电荷转移程度介于零（中性分子固体）和一（完全电荷转移，完全离子固体）之间。似乎具有这些互补性质的一种分子组合，即相反对称的前沿轨道和有希望匹配的氧化还原性质，是四硫代戊烯（TTF， II）家族的供体和四halo-/？-苯醌（III）受体家族。我们发现TTF和TMTTF（四甲基TTF）与每一种四卤对苯醌形成1:1组成的电荷转移化合物。此外，几乎每一种供体和受体的结合都至少形成两个不同的相。在本通讯中，我们将只讨论那些高导电性的盐。这里讨论的材料通常是通过在溶剂的沸点下混合施主和受主的乙腈溶液并冷却到室温来制备的。表1总结了所得盐的压粉末电导率，以及TTF-TCNQ8和TMTTF-TCNQ的相应测量值。值得注意的是，其中四种新化合物（表1）
III x4BQ X= F, Cl, Br, 1 in which donor and acceptor molecules alternate. The approach4 that we have followed is one of attempting to inhibit good donor-acceptor orbital overlap, thereby minimizing the Mulliken charge-transfer interaction that stabilizes such mixed stacks, with the idea that segregated stacks might be formed by default. One way of creating unfavorable donor-acceptor overlap is to select a pair of molecules such that the relevant frontier orbitals (HOMO of the donor and LUMO of the ac-ceptor, shown schematically (Scheme I) for molecules I, II and III) are of different symmetry with respect to inversion. To meet the criterion of partial charge transfer, we have used2-3 electrochemical half-wave potentials as a relative measure of the ionization potential of the donor and the electron affinity of the acceptor. These values, combined with consideration of the electrostatic crystalline binding energy, can be used as a crude guide for selecting molecules3 such that the degree of charge transfer will be between zero (neutral molecular solid) and one (complete charge transfer, fully ionic solid). One combinationof molecules that appears to possess these complementary properties, ie, frontier orbitals of opposite symmetry and promising match of redox properties, are the tetrathiafulvalene (TTF, II) family of donors and the tetrahalo-/?-benzoquinone (III) family of acceptors. We have found6 that TTF and TMTTF (tetramethyl-TTF) form charge-transfer compounds of 1: 1 composition with each of the tetrahalo-p-benzoquinones. Furthermore, nearly every combination of donor and acceptor forms atleast two distinct phases. 4-7 In this communication we shall discuss only those salts which are highly conducting. The materials discussed here were generally prepared by mixing acetonitrile solutions of the donor and acceptortogether at the boiling point of the solvent and cooling to room tem-perature. The pressed powder conductivities of the resulting salts are summarized in Table I, along with corresponding values measured for TTF-TCNQ8 and TMTTF-TCNQ. 9 It should be noted that four of these new compounds (Table I)