1,8-Disubstituted Xanthylidene-based Remote Carbenes: Photolytic Generation and Isolation of Low-coordinate Palladium(II) Complex
1,8-Disubstituted Xanthylidene-based Remote Carbenes: Photolytic Generation and Isolation of Low-coordinate Palladium(II) Complex
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1,8-二取代呫吨基远程卡宾：低配位钯(II)配合物的光解生成和分离
DOI：
10.1002/ejic.201403017
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发表时间：
2015
影响因子：
2.3
通讯作者：
Y.
中科院分区：
文献类型：
--
作者：
Sugawara;S.; Abe;M.; Fujiwara;Y.; Wakioka;M.; Ozawa;F.; Yamamoto;Y.
具有比N-杂环卡宾（NHC）更强的σ-给体和π-受体性质的卡宾的分离和研究一直被认为是卡宾化学的重大挑战之一。我们通过两种不同的方法研究了基于1，8-二取代占吨亚甲基的化合物的性质：光解诱导形成游离卡宾和通过氧化加成合成相应的金属-卡宾络合物。前一项研究表明，在1-和8-位未取代的卡宾比母体xanthylidene在动力学上更具反应性，并且在1-和8-位的取代基在通过光解生成卡宾方面不太有效。然而，钯（0）与1，8-二苯基取代的前体的氧化加成成功地得到了低配位的14电子钯（II）-卡宾络合物。这种不寻常的复合物是稳定的不可知的相互作用，涉及相邻的苯基。该配合物是迄今为止报道的稳定的阳离子14电子钯（II）-卡宾配合物的第二个例子。
The isolation and study of carbenes with σ‐donating and π‐accepting properties stronger than those of N‐heterocyclic carbenes (NHCs) have been regarded as one of the big challenges in carbene chemistry. We have investigated the properties of 1,8‐disubstituted xanthylidene‐based compounds by using two different approaches: The photolysis‐induced formation of free carbenes and the synthesis of the corresponding metal–carbene complexes by oxidative addition. The former study revealed that the carbene unsubstituted at the 1‐ and 8‐positions is kinetically more reactive than the parent xanthylidene and that the substituents at the 1‐ and 8‐positions are less effective in generating carbenes by photolysis. However, oxidative addition of palladium(0) to the 1,8‐diphenyl‐substituted precursor successfully afforded a low‐coordinate 14‐electron palladium(II)–carbene complex. This unusual complex is stabilized by agnostic interactions involving an adjacent phenyl group. This complex is the second example of a stable cationic 14‐electron palladium(II)–carbene complex to have been reported so far.