Leandri Valentina, Daniel Quentin, Chen Hong, Sun Licheng, Gardner James M, Kloo Lars
Applied Physical Chemistry, Department of Chemistry , KTH Royal Institute of Technology , SE-10044 , Stockholm , Sweden.
Organic Chemistry, Centre of Molecular Devices, Department of Chemistry, School of Chemical Science and Engineering , KTH Royal Institute of Technology , SE-100 44 , Stockholm , Sweden.
Inorg Chem. 2018 Apr 16;57(8):4556-4562. doi: 10.1021/acs.inorgchem.8b00225. Epub 2018 Apr 2.
The reaction of CuCl with 2,9-dimethyl-1,10-phenanthroline (dmp) does not lead to the formation of Cu(dmp) but instead to [Cu(dmp)Cl]Cl, a 5-coordinated complex, in which one chloride is directly coordinated to the metal center. Attempts at removing the coordinated chloride by changing the counterion by metathesis were unsuccessful and resulted only in the exchange of the noncoordinated chloride, as confirmed from a crystal structure analysis. Complex [Cu(dmp)Cl]PF exhibits a reversible cyclic voltammogram characterized by a significant peak splitting between the reductive and oxidative waves (0.85 and 0.60 V vs NHE, respectively), with a half-wave potential E = 0.73 V vs NHE. When reduced electrochemically, the complex does not convert into [Cu(dmp)], as one may expect. Instead, [Cu(dmp)] is isolated as a product when the reduction of [Cu(dmp)Cl]PF is performed with l-ascorbic acid, as confirmed by electrochemistry, NMR spectroscopy, and diffractometry. [Cu(dmp)] complexes can be synthesized starting from Cu(II) salts with weakly and noncoordinating counterions, such as perchlorate. Growth of Cu(dmp) crystals in acetonitrile results in a 5-coordinated complex, Cu(dmp)(CHCN), in which a solvent molecule is coordinated to the metal center. However, solvent coordination is associated with a dynamic decoordination-coordination behavior upon reduction and oxidation. Hence, the cyclic voltammogram of [Cu(dmp)(CHCN)] is identical to the one of [Cu(dmp)], if the measurements are performed in acetonitrile. The current results show that halide ions in precursors to Cu(II) metal-organic coordination compound synthesis, and most likely also other multivalent coordination centers, are not readily exchanged when exposed to presumed strongly binding and chelating ligand, and thus special care needs to be taken with respect to product characterization.
氯化铜（CuCl）与2,9 - 二甲基 - 1,10 - 菲咯啉（dmp）反应并不会生成Cu(dmp)，而是生成[Cu(dmp)Cl]Cl，一种五配位络合物，其中一个氯离子直接与金属中心配位。通过复分解反应改变抗衡离子来除去配位氯离子的尝试未成功，且仅导致未配位氯离子的交换，这已通过晶体结构分析得到证实。络合物[Cu(dmp)Cl]PF显示出可逆的循环伏安图，其特征在于还原波和氧化波之间有明显的峰分裂（分别相对于标准氢电极（NHE）为0.85和0.60 V），半波电位E相对于NHE为0.73 V。当进行电化学还原时，该络合物并不会如预期那样转化为[Cu(dmp)]。相反，用电化学、核磁共振光谱和衍射测定法证实，当用L - 抗坏血酸对[Cu(dmp)Cl]PF进行还原时，[Cu(dmp)]作为产物被分离出来。[Cu(dmp)]络合物可以从具有弱配位和非配位抗衡离子（如高氯酸盐）的铜（II）盐开始合成。在乙腈中生长Cu(dmp)晶体得到一种五配位络合物Cu(dmp)(CHCN)，其中一个溶剂分子与金属中心配位。然而，溶剂配位在还原和氧化时伴随着动态的去配位 - 配位行为。因此，如果在乙腈中进行测量，[Cu(dmp)(CHCN)]的循环伏安图与[Cu(dmp)]的相同。目前的结果表明，在合成铜（II）金属 - 有机配位化合物的前体中，卤离子以及很可能还有其他多价配位中心，在暴露于假定的强结合和螯合配体时不易交换，因此在产物表征方面需要特别小心。
