Zhang Wen, Zhao Fei, Liu Tao, Yuan Mei, Wang Zhe-Ming, Gao Song
Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
Inorg Chem. 2007 Apr 2;46(7):2541-55. doi: 10.1021/ic062062h. Epub 2007 Mar 1.
2-(2H-Tetrazol-5-yl)-1,10-phenanthroline (HL0), its alkyl-substituted derivatives (Ln, where n = 1-8, 10, 12, 14, and 16, denoting the carbon atom number of the alkyl chain) at the 2H position of the tetrazole ring, and their iron(II) complexes (a for [Fe(L0)2], na for Fe(Ln)22, and nb for Fe(Ln)22) were synthesized and characterized. The crystal structures of a, a.CH3OH, 1a.CH3OH, 1b.CH3OH.CH3CN, 2a.H2O, 2b.H2O, 4b.CH3OH, 5a.H2O, 5b.H2O, 6a, 6b, 7a, 7b, and 16a are described, along with thermal analyses. a undergoes an abrupt spin crossover (SCO) at 255 K with a hysteresis loop of 6 K. a.CH3OH, 2a.H2O, and 2b.H2O exhibit irreversible SCO behaviors due to the loss of solvent molecules upon heating. 3a, 3b, 4a, and 5a.H2O show simple spin transitions above 350 K. The desolvated samples of 4b.CH3OH and 5b.H2O undergo two-step spin transitions. 16a exhibits a two-step SCO behavior between 100 and 300 K, corresponding to sequential phase transitions from the low-spin (LS) phase to the intermediate phase and then to the high-spin phase, respectively, proved by crystal structure analysis and 57Fe Mössbauer spectroscopy. 1a.CH3OH, 10a, 10b, 12a, 12b, 14a, 14b, and 16b show gradual and incomplete SCO behaviors after cooling down from 400 K. 1b.CH3OH.CH3CN, 6a, 6b, 7a, 7b, 8a, and 8b remain in the LS state even at 400 K. This proves that the alkyl side chains, together with the solvent molecules and anions, play a crucial role in the complicated SCO behaviors in this system.
合成并表征了2-(2H-四唑-5-基)-1,10-菲咯啉(HL0)、其在四唑环2H位置带有烷基取代衍生物(Ln，其中n = 1 - 8、10、12、14和16，表示烷基链的碳原子数)及其铁(II)配合物([Fe(L0)2]为a，Fe(Ln)22为na，Fe(Ln)22为nb)。描述了a、a·CH3OH、1a·CH3OH、1b·CH3OH·CH3CN、2a·H2O、2b·H2O、4b·CH3OH、5a·H2O、5b·H2O、6a、6b、7a、7b和16a的晶体结构以及热分析。a在255 K发生突然的自旋交叉(SCO)，滞后回线为6 K。a·CH3OH、2a·H2O和2b·H2O由于加热时溶剂分子的损失而表现出不可逆的SCO行为。3a、3b、4a和5a·H2O在350 K以上显示简单的自旋转变。4b·CH3OH和5b·H2O的去溶剂化样品经历两步自旋转变。16a在100至300 K之间表现出两步SCO行为，分别对应于从低自旋(LS)相到中间相再到高自旋相的连续相变，这通过晶体结构分析和57Fe穆斯堡尔谱得到证实。1a·CH3OH、10a、10b、12a、12b、14a、14b和16b从400 K冷却后表现出逐渐且不完全的SCO行为。1b·CH3OH·CH3CN、6a、6b、7a、7b、8a和8b即使在400 K时仍保持在LS状态。这证明烷基侧链与溶剂分子和阴离子一起在该体系复杂的SCO行为中起关键作用。
