Spencer Douglas J E, Reynolds Anne M, Holland Patrick L, Jazdzewski Brian A, Duboc-Toia Carole, Le Pape Laurent, Yokota Seiji, Tachi Yoshimitsu, Itoh Shinobu, Tolman William B
Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, USA.
Inorg Chem. 2002 Dec 2;41(24):6307-21. doi: 10.1021/ic020369k.
A series of Cu(I) and Cu(II) complexes of a variety of beta-diketiminate ligands (L(-)) with a range of substitution patterns were prepared and characterized by spectroscopic, electrochemical, and, in several cases, X-ray crystallographic methods. Specifically, complexes of the general formula LCuCl were structurally characterized and their magnetic properties assessed through EPR spectroscopy of solutions and, in one instance, by variable-temperature SQUID magnetization measurements on a powder sample. UV-vis spectra indicated reversible dissociation to 3-coordinate monomers LCuCl in solution at temperatures above -55 degrees C. The Cu(I) complexes LCu(MeCN) exhibited reversible Cu(I)/Cu(II) redox couples with E(1/2) values between +300 and +520 mV versus NHE (cyclic voltammetry, MeCN solutions). These complexes were highly reactive with O(2), yielding intermediates that were identified as rare examples of neutral bis(mu-oxo)dicopper complexes on the basis of their EPR silence, diagnostic UV-vis absorption data, and O-isotope-sensitive resonance Raman spectroscopic features. The structural features of the compounds LCuCl and LCu(MeCN) as well as the proclivity to form bis(mu-oxo)dicopper products upon oxygenation of the Cu(I) complexes are compared to data previously reported for complexes of more sterically hindered beta-diketiminate ligands (Aboelella, N. W.; Lewis, E. A.; Reynolds, A. M.; Brennessel, W. W.; Cramer, C. J.; Tolman, W. B. J. Am. Chem. Soc. 2002, 124, 10600. Spencer, D. J. E.; Aboelella, N. W.; Reynolds, A. M.; Holland, P. L.; Tolman, W. B. J. Am. Chem. Soc. 2002, 124, 2108. Holland, P. L.; Tolman, W. B. J. Am. Chem. Soc. 1999, 121, 7270). The observed structural and reactivity differences are rationalized by considering the steric influences of both the substituents on the flanking aromatic rings and those present on the beta-diketiminate backbone.
制备了一系列具有多种取代模式的β - 二酮亚胺配体（L(-)）的Cu(I)和Cu(II)配合物，并通过光谱、电化学方法以及在几种情况下通过X射线晶体学方法对其进行了表征。具体而言，对通式为[LCuCl]₂的配合物进行了结构表征，并通过溶液的电子顺磁共振光谱以及在一个实例中通过对粉末样品进行变温超导量子干涉仪磁化测量来评估其磁性能。紫外可见光谱表明，在温度高于 -55℃时，这些配合物在溶液中可逆解离为三配位单体LCuCl。Cu(I)配合物LCu(MeCN)表现出可逆的Cu(I)/Cu(II)氧化还原对，相对于标准氢电极（NHE），其E(1/2)值在 +300至 +520 mV之间（循环伏安法，乙腈溶液）。这些配合物与O₂反应活性很高，生成的中间体根据其电子顺磁共振沉默、诊断性紫外可见吸收数据以及对O同位素敏感的共振拉曼光谱特征，被确定为中性双（μ - 氧）二铜配合物的罕见实例。将化合物[LCuCl]₂和LCu(MeCN)的结构特征以及Cu(I)配合物氧化时形成双（μ - 氧）二铜产物的倾向与先前报道的空间位阻更大的β - 二酮亚胺配体配合物的数据（Aboelella, N. W.; Lewis, E. A.; Reynolds, A. M.; Brennessel, W. W.; Cramer, C. J.; Tolman, W. B. J. Am. Chem. Soc. 2002, 124, 10600. Spencer, D. J. E.; Aboelella, N. W.; Reynolds, A. M.; Holland, P. L.; Tolman, W. B. J. Am. Chem. Soc. 2002, 124, 2108. Holland, P. L.; Tolman, W. B. J. Am. Chem. Soc. 1999, 121, 7270）进行了比较。通过考虑侧翼芳环上的取代基以及β -二酮亚胺主链上的取代基的空间影响，对观察到的结构和反应性差异进行了合理化解释。
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