Structural, spectroscopic, and electrochemical behavior of trans-phenolato cobalt(<scp>iii</scp>) complexes of asymmetric NN′O ligands as archetypes for metallomesogens
作者:Rajendra Shakya、Camille Imbert、Hrant P. Hratchian、Mauricio Lanznaster、Mary Jane Heeg、Bruce R. McGarvey、Marco Allard、H. Bernhard Schlegel、Claudio N. Verani
DOI:10.1039/b514190g
日期:——
In order to understand and predict structural, redox, magnetic, and optical properties of more complex and potentially mesogenic electroactive compounds such as [CoIII(Lt-BuLC)2]ClO4 (1), five archetypical complexes of general formula [CoIII(LRA)2]ClO4, where R = H (2), tert-butyl (3), methoxy (4), nitro (5), and chloro (6), were obtained and studied by means of several spectrometric, spectroscopic, and electrochemical methods. The complexes 2, 4, and 6 were characterized by single-crystal X-ray diffraction, and show the metal center in an approximate D2h symmetry. Experimental results support the fact that the electron donating or withdrawing nature of the phenolate-appended substituents changes dramatically the redox and spectroscopic properties of these compounds. The 3d6 electronic configuration of the metal ion dominates the overall geometry adopted by these compounds with the phenolate rings occupying trans positions to one another. Formation of phenoxyl radicals has been observed for 1, 3, and 6, but irreversible ligand oxidation takes place upon bulk electrolysis. These data were compared to detailed B3LYP/6-31G (d)-level computational calculations and have been used to account for the results observed. A comparison between compound 1 and archetype 3, validates the approach of using archetypical models to study metal-containing soft materials.
为了了解和预测[CoIII(Lt-BuLC)2]ClO4 (1)等更为复杂且可能具有介电性的电活性化合物的结构、氧化还原、磁性和光学特性,我们提出了五种典型的通式[CoIII(LRA)2]ClO4、通过几种光谱学、能谱学和电化学方法,研究了五种通式为 [CoIII(LRA)2]ClO4 的典型配合物,其中 R = H (2)、叔丁基 (3)、甲氧基 (4)、硝基 (5) 和氯基 (6)。络合物 2、4 和 6 采用单晶 X 射线衍射表征,显示金属中心近似为 D2h 对称。实验结果证明,苯酚取代基的供电子或取电子性质极大地改变了这些化合物的氧化还原和光谱特性。金属离子的 3d6 电子构型主导了这些化合物采用的整体几何形状,苯酚环彼此占据反式位置。在 1、3 和 6 中观察到苯氧自由基的形成,但在大量电解时会发生不可逆的配体氧化。这些数据与详细的 B3LYP/6-31G (d)-level 计算结果进行了比较,并用于解释所观察到的结果。化合物 1 与原型 3 之间的比较验证了使用原型模型研究含金属软材料的方法。