Synthesis of an ambient temperature stable, high spin density organic solid with an anomalously small interspin coupling
Synthesis of an ambient temperature stable, high spin density organic solid with an anomalously small interspin coupling
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具有异常小的自旋间耦合的环境温度稳定的高自旋密度有机固体的合成
DOI：
10.1021/ja00187a082
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发表时间：
1989
影响因子：
15
通讯作者：
A. Bloch
中科院分区：
文献类型：
--
作者：
L. Chiang;D. Johnston;D. Goshorn;A. Bloch
1926年J. Am.化学会，Vol. III，No.5，1989给编辑的通讯tadecahydrohexazacoronene 2 3（HOC）已经被合成用作高自旋固态有机材料的前体。然而，这些双阳离子三重态有机物不是热稳定的。例如，发现溶液中双阳离子HMT的三重态仅在低于低温时稳定。[23]在此，我们报道了三重态双阳离子HMT分子，在HMT与某些受体反应和掺杂过程之后，可以在环境温度下稳定在固态，以形成具有高自旋密度和非常小的自旋间耦合的新型有机电荷转移盐。本研究的最佳有机受体是2，3，5，6-四氟-7，7，8，8-四氰基醌二甲烷（2（TCNQF_4））。所得的红紫色结晶复合物具有分子组成（HMT）2-TCNQF 4（3）。4· 5对化学掺杂的（HMT）2-TCNQF 4样品进行了磁化率和ESR研究。首次研究了未掺杂的（HMT）2-TCNQF_4微晶固体，根据ESR磁化率测量证明其仅为弱顺磁性。实际上，静态磁化率数据表明自旋密度仅对应于0.1摩尔%自旋1/2。掺杂过程在（HMT）2-TCNQF 4络合物的固态下用五氟化砷气体进行。从该方法中，我们发现氟化砷的含量从27重量%变化到62重量%，其对应于分子式（HMT）2-TCNQF 4-（AsF 5）y（4，y= 2.0-8.4）。据报道，掺入AsF 5的聚芳烃中的氟化砷主要以单阴离子AsF 5-AsF 6的络合形式存在。** 这得到4在低掺杂水平（络合物5）下的磁性数据的支持，该数据显示在计算与我们的掺杂络合物的实验和IR光谱研究之间每个络合物单元的自旋数匹配，其显示在400和700 cm-1处的两个强区别带。然而，更复杂的反应导致其他类型（2）（a）Bechgaard，K.;帕克，V. DJ Am. 1972，94，4749中所述。(b)马斯格雷夫岛C.的;韦伯斯特，CJ J.化学学会，1971，1397。蒋湖Y的;约翰斯顿，D. C; Stokes，JP; Bloch，AN Synth. Met. 1987年，19，697。(3)Breslow，R.; Maslak，P.;作者：JJ Am. 1984，106，6453中所述。LePage，T. J.道：Breslow，RJ Am. 1987，109，6412中所述。J. J. Maslak，P.;布雷斯洛河J. Am. 1988，110，3970中所述。(4)晶体3的振荡Weissenberg照片给出晶胞参数a= 30 μ m（约为HMT分子直径的两倍），B（沿晶体针状轴的堆积方向沿着）= 9.9 μ m，c（非常无序）。6轴晶格常数是芳香分子厚度的3倍。这表明，两个HMT分子与一个TCNQF 4分子在一维阵列中沿针轴沿着排列，形成一种结构。爸爸沿O轴方向的大沿着无序可能是由于HMT和TCNQF_4在尺寸和对称性上有很大的不同。在这种分子比例和堆积性质的特定组合中，二维的有序有利于第三维的无序。(5)3的混合堆结构的间接证据来自于它的输运性质。发现晶体3沿针轴沿着的四探针室温电阻率为10 cm。如果配合物3具有一个分离子堆积结构，在HMT和TCNQF_4之间有部分电荷转移（每个TCNQF_4有0.2个电荷），它应该具有类似于有机金属或有机化合物的导电性。
1926 J. Am. Chem. Soc., Vol. Ill, No. 5, 1989 Communications to the Editor tadecahydrohexaazacoronene2 3 (HOC), have been synthesized for use as precursors in the preparationof high-spin solid-state organic materials. However, these dicationic triplet organics are not thermally stable. For example, the triplet state of dicationic HMT in solution was found to be stable only below the cryogenic temperature. 23 Here we report that triplet dicationic HMT molecules, after a reaction of HMT with certain acceptors and a doping process, can be stabilized in the solid state at ambient temperature to form novel organic charge-transfer salts possessing a high spin density with an anomalously small interspin coupling. The optimum organic acceptor for this study was found to be 2, 3, 5, 6-tetrafluoro-7, 7, 8, 8-tetracyanoquinodimethane (2 (TCNQF4)). The resulting reddish purple crystalline complex possesses a molecular composition (HMT) 2-TCNQF4 (3). 4· 5 Magnetic susceptibility andESR6 studies were performed on chemically doped samples of (HMT) 2-TCNQF4. The undoped (HMT) 2-TCNQF4 microcrystalline solid was studied first and proved to be only weakly paramagnetic according to ESR sus-ceptibility measurements. In fact, the static susceptibility data indicated a spin density corresponding to only 0.1 mol% spins 1/2. The doping process was carried out at the solid state of the (HMT) 2-TCNQF4 complex with arsenic pentafluoride gas. From this process we found that the contents of arsenic fluorides varied from 27% by weight to 62% by weight, which corresponds to a molecular formula (HMT) 2-TCNQF4-(AsF5¡) y (4, y= 2.0-8.4). It was reported that the main fractionof arsenic fluorides incorporated in AsF5-doped polyaromatics is a complex formof monoanionic AsF5-AsF6. 7** This is supported by the magnetic data of 4 at the low doping level (complex 5) showing a matched number of spins per complex unit between calculation and an experimental and IR spectroscopic study of our doped complex, which showed two strong distinguishing bands at 400 and 700 cm'1. However, more complicated reactions leading to other types (2)(a) Bechgaard, K.; Parker, V. DJ Am. Chem. Soc. 1972, 94, 4749.(b) Musgrave, O. C.; Webster, CJ J. Chem. Soc. 1971, 1397. Chiang, L. Y.; Johnston, D. C; Stokes, JP; Bloch, AN Synth. Met. 1987, 19, 697.(3) Breslow, R.; Maslak, P.; Thomaides, JJ Am. Chem. Soc. 1984, 106, 6453. LePage, T. J.; Breslow, RJ Am. Chem. Soc. 1987, 109, 6412. Thomaides, J.; Maslak, P.; Breslow, R. J. Am. Chem. Soc. 1988, 110, 3970.(4) The oscillation Weissenberg photograph of crystal 3 gave unit cell parameters a= 30 Á (roughlytwice the HMT molecular diameter), b (stacking direction along the needle axis of crystal)= 9.9 Á, and c (very disordered). The 6-axis lattice constant is 3 times the thickness of an aromatic molecule. This indicates that two HMT molecules alternate with one TCNQF4 molecule in a one-dimensional array along the needle axis in a structure of... DADDAD... Thelarge disorder along the oaxis possibly results from the fact that HMT and TCNQF4 are quite different in size and sym-metry. In this particular combination of molecular ratio and stacking nature, the order in two dimensions favors disorder in the third dimension.(5) The indirect evidence of the mixed-stack structure of 3 is derived from its transport properties. The four-probe room temperature resistivity of crystal 3 along the needle axis was found to be 10 cm. If complex 3has a segregated-stack structure, with a partial charge transfer (0.2 charge per TCNQF4) between HMT and TCNQF4, it should give an appreciable con-ductivity such as that of an organic metal or …