An EMI-based room-temperature (RT) ionic liquid containing d5 trivalent iron(III) ions [EMI][FeIIICl4] was fully investigated, where EMI is 1-ethyl-3-methylimidazolium. The viscosity of the salt is 14 cP at 30 °C, and its ionic conductivity is as high as 1.8 × 10−2 S cm−1 at 20 °C. The high conductivity and fluidity can be attributed to the reduced interionic Coulomb attractions owing to the nephelauxetic effect. Magnetic susceptibility shows the Curie–Weiss behavior arising from S = 5/2 high-spin electronic state on iron(III) ions in both liquid and solid states, leading to the conductive–paramagnetic bifunctional RT ionic liquid. The solidified salt passes through an antiferromagnetic transition at 4.2 K. Diamagnetic [EMI][GaIIICl4] and paramagnetic [EMI][FeIIICl4]0.5[GaIIICl4]0.5 are also RT ionic liquids and show similar conductivities (1.8–2.0 × 10−2 S cm−1 at 20 °C) and viscosities (12–13 cP at 30 °C). These results indicate that the influence of paramagnetic iron(III) ions upon the ionic conductivity and viscosity is negligible in the present system. A 2:1 EMI salt containing d6 divalent iron(II) ions [EMI]2[FeIICl4] melts at 86 °C. Its crystal structure determined by a synchrotron X-ray powder diffraction measurement is analogous to those of the reported [EMI]2[CoIICl4] and [EMI]2[NiIICl4] with expanded lattice.
对一种含有 d5 三价
铁(III)离子[
EMI][FeIIICl4]的基于
EMI 的室温(RT)
离子液体进行了全面研究,其中
EMI 为 1-乙基-3-甲基
咪唑鎓。该盐在 30 °C 时的粘度为 14 cP,在 20 °C 时的离子电导率高达 1.8 × 10-2 S cm-1。高电导率和流动性可归因于新白化效应减少了离子间的库仑吸引力。在液态和固态下,
铁(III)离子上的 S = 5/2 高自旋电子态产生了居里-魏斯磁感应强度,从而形成了导电、顺磁性双功能 RT
离子液体。固态盐在 4.2 K 时通过了反
铁磁转变。二磁 [
EMI][GaIIICl4]和顺磁 [
EMI][FeIIICl4]0.5[GaIIICl4]0.5 也是 RT
离子液体,并显示出相似的电导率(20 °C 时为 1.8-2.0 × 10-2 S cm-1)和粘度(30 °C 时为 12-13 cP)。这些结果表明,在目前的体系中,顺磁
铁(III)离子对离子电导率和粘度的影响可以忽略不计。含有 d6 二价
铁(II)离子的 2:1
EMI 盐 [
EMI]2[FeIICl4]在 86 °C 时熔化。通过同步辐射 X 射线粉末衍射测量确定的晶体结构与已报道的具有扩展晶格的 [
EMI]2[CoIICl4] 和 [
EMI]2[NiIICl4] 类似。