Department of Chemistry, College of Humanities and Sciences, Nihon University, Setagaya-Ku, Tokyo, Japan.
J Am Chem Soc. 2012 Aug 1;134(30):12724-31. doi: 10.1021/ja3044757. Epub 2012 Jul 19.
Crystals of the single-component molecular conductor [Cu(dmdt)(2)] (dmdt = dimethyltetrathiafulvalenedithiolate) were prepared as a molecular system, with three-dimensionally arranged magnetic moments embedded in "sea" of π conduction electrons. [Cu(dmdt)(2)] had fairly large room-temperature conductivity (110 S cm(-1)) and exhibited weakly metallic behavior near room temperature. Below 265 K, the resistivity (R) increased very slowly with decreasing temperature and then increased rapidly, indicating a transition from a highly conducting state to an insulating state near 95 K. The magnetic susceptibility showed Curie-Weiss behavior at 100-300 K (C = 0.375 emu/mol, Θ = 180 K). The Curie constant and the high-temperature resistivity behavior indicate that conduction electrons and three-dimensionally arranged magnetic moments coexist in the crystal. The ESR intensity increased down to about 95 K. The ESR signal was broadened and decreased abruptly near 95 K, suggesting that electric and antiferromagnetic transitions occurred simultaneously near 95 K. The crystal structure was determined down to 13 K. To examine the stability of the twisted conformation of Cu complex with dithiolate ligands, the dihedral angle dependence of the conformational energy of an isolated M(L)(2)(n-) molecule was calculated, which revealed the dihedral angle dependence on the ligand (L) and the oxidation state of the molecule (n). High-pressure four-probe resistivity measurements were performed at 3.3-9.3 GPa using a diamond anvil cell. The small resistivity increase observed at 3.3 GPa below 60 K suggested that the insulating transition observed at ambient pressure near 95 K was essentially suppressed at 3.3 GPa. The intermolecular magnetic interactions were examined on the basis of simple mean field theory of antiferromagnetic transition and the calculated intermolecular overlap integrals of the singly occupied molecular orbital (SOMO) of Cu(dmdt)(2).
[Cu(dmdt)(2)]（dmdt = 二甲基四硫富瓦烯二硫醇盐）的单组分分子导体单晶被制备为一个分子体系，其中三维排列的磁矩嵌入在“π 传导电子海洋”中。[Cu(dmdt)(2)]在室温下具有相当大的电导率（110 S cm(-1)），并在室温附近表现出弱金属行为。在 265 K 以下，电阻率（R）随温度的降低缓慢增加，然后迅速增加，表明在 95 K 附近从高导电状态向绝缘状态转变。在 100-300 K 时，磁化率表现出居里-外斯行为（C = 0.375 emu/mol，Θ = 180 K）。居里常数和高温电阻率行为表明，在晶体中存在传导电子和三维排列的磁矩。ESR 强度在 95 K 以下下降。ESR 信号在 95 K 附近变宽并急剧下降，表明在 95 K 附近同时发生了电和反铁磁转变。晶体结构在 13 K 以下确定。为了检查 Cu 配合物与二硫醇配体的扭曲构象的稳定性，计算了孤立的 M(L)(2)(n-)分子构象能的二面角依赖性，这揭示了二面角对配体（L）和分子的氧化态（n）的依赖性。在 3.3-9.3 GPa 下使用金刚石砧细胞进行了高压四点探针电阻率测量。在 3.3 GPa 以下 60 K 以下观察到的小电阻率增加表明，在环境压力下在 95 K 附近观察到的绝缘转变在 3.3 GPa 下基本上被抑制。基于反铁磁转变的简单平均场理论和 Cu(dmdt)(2)的单占据分子轨道（SOMO）的计算分子间重叠积分，研究了分子间磁相互作用。
