N‐Heterocyclic Olefins as Electron Donors in Combination with Triarylborane Acceptors: Synthesis, Optical and Electronic Properties of D–π–A Compounds
作者:Jiang He、Florian Rauch、Alexandra Friedrich、Daniel Sieh、Tatjana Ribbeck、Ivo Krummenacher、Holger Braunschweig、Maik Finze、Todd B. Marder
DOI:10.1002/chem.201903118
日期:2019.10.28
N-heterocyclic olefins (NHOs), relatives of N-heterocyclic carbenes (NHCs), exhibit high nucleophilicity and soft Lewis basic character. To investigate their π-electron donating ability, NHOs were attached to triarylborane π-acceptors (A) giving donor (D)-π-A compounds 1-3. In addition, an enamine π-donor analogue (4) was synthesized for comparison. UV-visible absorption studies show a larger red shift
N-杂环卡宾(NHC)的亲戚N-杂环烯烃(NHOs)具有高亲核性和柔软的Lewis基本特征。为了研究其π电子给体能力,将NHOs连接到三芳基硼烷π受体(A)上,得到供体(D)-π-A化合物1-3。另外,合成了烯胺π供体类似物(4)用于比较。紫外线可见吸收研究表明,含NHO的硼烷的红移大于烯胺类似物(环(烷基)(氨基)羧甲酸酯(CAAC)的亲戚)的红移。溶剂依赖性排放研究表明1-4具有中等分子内电荷转移(ICT)行为。电化学研究表明,含NHO的硼烷具有极低的可逆氧化电位(例如,在THF中,三氧化二铁1/2 = -0.40 V相对于二茂铁/二茂铁Fc / Fc +)。