Department of Chemistry, Georgetown University , Box 571227-1227, Washington, D.C. 20057, United States.
Department of Chemistry, Purdue University , 560 Oval Drive, West Lafayette, Indiana 47907, United States.
J Am Chem Soc. 2017 Jul 12;139(27):9112-9115. doi: 10.1021/jacs.7b04046. Epub 2017 Jun 29.
Copper(II) aryl species are proposed key intermediates in Cu-catalyzed cross-coupling reactions. Novel three-coordinate copper(II) aryls [Cu]-CF supported by ancillary β-diketiminate ligands form in reactions between copper(II) alkoxides [Cu]-OBu and B(CF). Crystallographic, spectroscopic, and DFT studies reveal geometric and electronic structures of these Cu(II) organometallic complexes. Reaction of [Cu]-CF with the free radical NO results in C-N bond formation to give Cu. Remarkably, addition of the phenolate anion PhO to [Cu]-CF directly affords diaryl ether PhO-CF with concomitant generation of the copper(I) species Cu and {[Cu]-CF}. Experimental and computational analysis supports redox disproportionation between [Cu]-CF and {Cu(OPh)} to give {[Cu]-CF} and Cu(OPh) unstable toward reductive elimination to Cu and PhO-CF.
铜（II）芳基物种被认为是铜催化交叉偶联反应中的关键中间体。新型三配位铜（II）芳基[Cu]-CF 由辅助β-二酮亚胺配体支持，在铜（II）醇盐[Cu]-OBu 和 B(CF)之间的反应中形成。晶体学、光谱学和 DFT 研究揭示了这些 Cu(II)有机金属配合物的几何和电子结构。[Cu]-CF 与自由基 NO 的反应导致 C-N 键形成，得到Cu。值得注意的是，将酚盐阴离子 PhO 添加到[Cu]-CF 中直接得到二芳基醚 PhO-CF，同时生成铜（I）物种Cu和{[Cu]-CF}。实验和计算分析支持[Cu]-CF 和{Cu(OPh)}之间的氧化还原歧化反应，生成{[Cu]-CF}和Cu(OPh)，它们不稳定，易于进行还原消除，生成Cu和 PhO-CF。
