Interactions Between the Trianionic Ligand-centred Redox-active Metalloligand [CrIII(perfluorocatecholato)3]3- and Guest Metal Ions
Interactions Between the Trianionic Ligand-centred Redox-active Metalloligand [CrIII(perfluorocatecholato)3]3- and Guest Metal Ions
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以三阴离子配体为中心的氧化还原活性金属配体 [CrIII(全氟儿茶酚)3]3- 与客体金属离子之间的相互作用
DOI：
10.1039/c5dt01963j
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发表时间：
2015
影响因子：
4
通讯作者：
H.-C. Chang
中科院分区：
文献类型：
--
作者：
M. Wakizaka;T. Matsumoto;A. Kobayashi;M. Kato;H.-C. Chang
合成了具有氧化还原活性的金属配体（RML）（Et 3 NH）3[CrIII（F4 Cat）3]（F4 Cat =全氟邻苯二酚）（1），并研究了其与客体金属离子Li+、Mn 2+、Fe 2+、Co 2+、Cu 2+和Zn 2+的相互作用。循环伏安法和光谱电化学研究表明，配合物1表现出三步配体中心的单电子氧化，连续生成[CrIII（F4 Cat）2（F4 SQ）]2-（F4 SQ =全氟半醌）、[CrIII（F4 Cat）（F4 SQ）2]−和[CrIII（F4 SQ）3]，电压为−0.12、0.23和0.53 V（相对于Ag/Ag+的二氯甲烷溶液），或电压为−0.21、0.08、和0.50V的乙腈（MeCN）溶液中。在MeCN中的滴定实验表明，用Cu 2+处理1导致通过氧化还原反应形成[CrIII（F4 Cat）2（F4 SQ）]2−和Cu+。然而，当用Li+、Mn 2+、Fe 2+、Co2+和Zn 2+处理1时，进一步的滴定实验表明，这些金属离子通过F4 Cat 2 −部分的配位氧原子上的孤对电子以一比一的比例配位，结合常数为3.7（±0.3）× 104（Li+）、1.5（±0.2）× 105（Mn 2+）、2.2（±0.4）× 105（Fe 2+）、1.9（±0.2）× 105（Co2+）和3.8（±0.4）× 105 M−1（Zn 2+）。此外，1的氧化电位正移了0.08-0.33 V后，添加客体金属离子。光谱电化学研究表明，1在存在的客体金属离子的配位体为中心的一个和两个电子的氧化的RML发生的Li+，Mn 2+，Co 2+，和Zn 2+，分别，而客体金属为中心的一个电子的氧化观察到的Fe 2+。考虑到所有上述结果，该研究首次证明了[CrIII（F4 Cat）3]3−在溶液中作为RML的能力。
The redox-active metalloligand (RML) (Et3NH)3[CrIII(F4Cat)3] (F4Cat = perfluorocatecholato) (1) was synthesized and its interactions with guest metal ions Li+, Mn2+, Fe2+, Co2+, Cu2+, and Zn2+ were examined. Cyclic voltammetry measurements and spectroelectrochemical studies revealed that complex 1 shows three-step ligand-centred one-electron oxidation to consecutively generate [CrIII(F4Cat)2(F4SQ)]2− (F4SQ = perfluorosemiquinonato), [CrIII(F4Cat)(F4SQ)2]−, and [CrIII(F4SQ)3] at −0.12, 0.23, and 0.53 V vs. Ag/Ag+ in dichloromethane, or at −0.21, 0.08, and 0.50 V in acetonitrile (MeCN), respectively. Titration experiments in MeCN revealed that treatment of 1 with Cu2+ leads to the formation of [CrIII(F4Cat)2(F4SQ)]2− and Cu+via a redox reaction. However, when 1 was treated with Li+, Mn2+, Fe2+, Co2+, and Zn2+, further titration experiments revealed that these metal ions coordinated via the lone pairs on the coordinating oxygen atoms of the F4Cat2− moieties in a one-to-one ratio, and binding constants of 3.7 (±0.3) × 104 (Li+), 1.5 (±0.2) × 105 (Mn2+), 2.2 (±0.4) × 105 (Fe2+), 1.9 (±0.2) × 105 (Co2+), and 3.8 (±0.4) × 105 M−1 (Zn2+) were established. Moreover, the oxidation potentials of 1 were positively shifted by 0.08–0.33 V upon addition of guest metal ions. Spectroelectrochemical studies of 1 in the presence of guest metal ions suggested that ligand-centred one- and two-electron oxidation of the RML occurred for Li+, Mn2+, Co2+, and Zn2+, respectively, while guest metal-centred one-electron oxidation was observed for Fe2+. Considering all the aforementioned results, this study demonstrated for the first time the ability of [CrIII(F4Cat)3]3− to act as a RML in solution.