Fujiwara Emiko, Hosoya Kazumasa, Kobayashi Akiko, Tanaka Hisashi, Tokumoto Madoka, Okano Yoshinori, Fujiwara Hideki, Kobayashi Hayao, Fujishiro Yuichi, Nishibori Eiji, Takata Masaki, Sakata Makoto
Research Centre for Spectrochemistry, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Inorg Chem. 2008 Feb 4;47(3):863-74. doi: 10.1021/ic701100r. Epub 2008 Jan 8.
To obtain novel single-component molecular metals, we attempted to synthesize several cobalt complexes coordinated by TTF (tetrathiafulvalene)-type dithiolate ligands. We succeeded in the syntheses and structure determinations of ((n)Bu(4)N)(2)Co(chdt)(2) (1), ((n)Bu(4)N)(2)Co(dmdt)(2) (2), Co(dmdt)(2) (3), and Co(dt)(2) (4) (chdt = cyclohexeno-TTF-dithiolate, dmdt = dimethyl-TTF-dithiolate, and dt = TTF-dithiolate). Structure analyses of complexes 1-4 revealed that two monomeric [Co(ligand)2]- or Co(ligand)(2) units are connected by two Co-S bonds resulting in dimeric Co(ligand)(2)(2-) or Co(ligand)(2) molecules. Complex 1 has a cation-anion-intermingled structure and exhibited Curie-Weiss magnetic behavior with a large Curie constant (C = 2.02 K x emu x mol(-1)) and weak antiferromagnetic interactions (theta = -8.3 K). Complex 2 also has a cation-anion-intermingled structure. However, the dimeric molecules are completely isolated by cations. Complexes 3 and 4 are single-component molecular crystals. The molecules of complex 3 form two-dimensional molecular stacking layers and exhibit a room-temperature conductivity of sigmart = 1.2 x 10(-2) S.cm(-1) and an activation energy of E(a) = 85 meV. The magnetic behavior is almost consistent with Curie-Weiss law, where the Curie constant and Weiss temperature are 8.7 x 10(-2) K x emu x mol(-1) and -0.85 K, respectively. Complex 4 has a rare chair form of the dimeric structure. The electrical conductivity was fairly large (sigmart = 19 S.cm(-1)), and its temperature dependence was very small (sigma(0.55K)/sigma(rt) = ca. 1:10), although the measurements were performed on the compressed pellet sample. Complex 4 showed an almost constant paramagnetic susceptibility (chi(300) (K) = 3.5 x 10(-4) emu x mol(-1)) from 300 to 50 K. The band structure calculation of complex 4 suggested the metallic nature of the system. Complex 4 is a novel single-component molecular conductor with a dimeric molecular structure and essentially metallic properties down to very low temperatures.
为了获得新型单组分分子金属，我们尝试合成了几种由TTF（四硫富瓦烯）型二硫醇盐配体配位的钴配合物。我们成功合成并确定了((n)Bu(4)N)(2)Co(chdt)(2)（1）、((n)Bu(4)N)(2)Co(dmdt)(2)（2）、Co(dmdt)(2)（3）和Co(dt)(2)（4）的结构（chdt = 环己烯基 - TTF - 二硫醇盐，dmdt = 二甲基 - TTF - 二硫醇盐，dt = TTF - 二硫醇盐）。配合物1 - 4的结构分析表明，两个单体[Co(配体)2]-或Co(配体)(2)单元通过两个Co - S键相连，形成二聚体Co(配体)(2)(2 - )或Co(配体)(2)分子。配合物1具有阳离子 - 阴离子混合结构，表现出居里 - 外斯磁行为，居里常数较大（C = 2.02 K·emu·mol(-1)）且反铁磁相互作用较弱（θ = -8.3 K）。配合物2也具有阳离子 - 阴离子混合结构。然而，二聚体分子被阳离子完全隔离。配合物3和4是单组分分子晶体。配合物3的分子形成二维分子堆积层，在室温下的电导率为σrt = 1.2×10(-2) S·cm(-1)，活化能为E(a) = 85 meV。磁行为几乎符合居里 - 外斯定律，其中居里常数和外斯温度分别为8.7×10(-2) K·emu·mol(-1)和 -0.85 K。配合物4具有罕见的二聚体结构椅式构型。尽管是在压缩片状样品上进行测量，但电导率相当大（σrt = 19 S·cm(-1)），其温度依赖性非常小（σ(0.55K)/σrt≈1:10）。配合物4在300至50 K范围内显示出几乎恒定的顺磁磁化率（χ(300) (K) = 3.5×10(-4) emu·mol(-1)）。配合物4的能带结构计算表明该体系具有金属性质。配合物4是一种新型单组分分子导体，具有二聚体分子结构，在极低温度下仍具有基本的金属特性。
