Three BDT-TTP [2,5-bis(1,3-dithiol-2-ylidene)-1,3,4,6-tetrathiapentalene] salts, (BDT-TTP)3[MIICl4](EtOH)x (M = Co, Mn, and Zn; x ≈ 1.0) were prepared. These salts are almost isostructural to one another. The crystals are composed of BDT-TTP columns, “BDT-TTP tapes” that occupy the interstitial positions between BDT-TTP columns, [MIICl4]2− anions and the crystal solvents, respectively. These salts showed weakly metallic conducting behavior down to about 150 K. At low temperature, the resistivities increased gradually with decreasing temperature, but the systems retained fairly high conductivities even at around 30 K. The [ZnIICl4]2− salt indicated temperature independent paramagnetism down to low temperature. While the susceptibilities of the [CoIICl4]2− and [MnIICl4]2− salts showed the coexistence of π conduction electrons and localized high-spins of the magnetic CoII and MnII atoms, no significant π–d interaction was observed. Band structure calculations were performed with taking account of the possibility of inhomogeneous distribution of π electrons over the crystallographically independent three BDT-TTP molecules. The system has wide and narrow one-dimensional bands that originate from BDT-TTP columns and tapes, respectively. However, due to the interaction between BDT-TTP columns and tapes, the system gave a unique two-dimensional electronic band. The calculated energy dispersion curves were consistent with the weakly metallic behavior of the systems.
制备了三种 BDT-
TTP [2,5-双(1,3-二
硫醇-2-亚基)-1,3,4,6-四
硫杂
戊烯] 盐 (BDT-
TTP)3[MIICl4](EtOH)x(M = Co、Mn 和 Zn;x ≈ 1.0)。这些盐几乎彼此同构。晶体分别由 BDT-
TTP 柱、占据 BDT-
TTP 柱间隙位置的 "BDT-
TTP 带"、[MIICl4]2- 阴离子和晶体溶剂组成。在低温条件下,电阻率随温度的降低而逐渐增大,但即使在 30 K 左右,这些体系仍保持了相当高的导电率。CoIICl4]2-盐和[MnIICl4]2-盐的磁感应强度表明π传导电子与磁性 CoII 原子和 MnII 原子的局部高自旋共存,但没有观察到明显的π-d 相互作用。在进行带状结构计算时,考虑到了π电子在晶体学上独立的三个 BDT-
TTP 分子上分布不均匀的可能性。该系统的一维宽带和窄带分别来自 BDT-
TTP 柱和带。然而,由于 BDT-
TTP 柱和带之间的相互作用,该体系产生了独特的二维电子带。计算得出的能量弥散曲线与系统的弱
金属行为一致。