• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Chemistry: A European journal >Imidazole to NHC rearrangements at molybdenum centers: An experimental and theoretical study
【24h】

Imidazole to NHC rearrangements at molybdenum centers: An experimental and theoretical study

机译：咪唑对NHC重排的钼中心：实验和理论研究

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Both manganese and rhenium complexes of the type [M(bipy)(CO) _3(N-RIm)]~+ (bipy=2,2′-bipyridine) undergo deprotonation of the central CH group of the N-alkylimidazole (N-RIm) ligand when treated with a strong base. However, the outcome of the reaction is very different for either metal. For Mn, the addition of the equimolar amount of an acid to the product of the deprotonation affords an N-heterocyclic carbene (NHC) complex, whereas for Re, once the deprotonation of the central imidazole CH group has occurred, the bipy ligand undergoes a nucleophilic attack on an ortho carbon, affording the C-C coupling product. The extension of these studies to pseudo-octahedral [Mo(η~3-allyl)(bipy)(CO)_2(N-RIm)] ~+ complexes has allowed us to isolate cationic NHC complexes (Mn I-type behavior), as well as their neutral imidazol-2-yl precursors. Theoretical studies of the reaction mechanisms using DFT computations were carried out on the deprotonation of [Mn(bipy)(CO)_3(N-PhIm)] ~+, [Re(bipy)(CO)_3(N-MesIm)]~+, and [Mo(η~3-C4H7)(bipy)(CO)_2(N-MesIm) ]~+ complexes (Mes=mesityl) at the B_3LYP/6-31G(d) (LANL2DZ for Mn, Re, and Mo) level of theory. Our results explain why different products have been found experimentally for Mn, Mo, and Re complexes. For Re, the process leading to a C-C coupling product is clearly more favored than those forming an imidazol-2-yl product. In contrast, for Mn and Mo complexes, the lower stabilizing interaction between the central imidazole and ortho bipy C atoms, along with the higher lability of the ligands, make the formation of an NHC-type product kinetically more accessible, in good agreement with experimental findings.
机译：[M（bipy）（CO）_3（N-RIm）]〜+（bipy = 2,2'-bipyridine）类型的锰和rh配合物都经历N-烷基咪唑（N- RIm）配体，用强碱处理时。但是，两种金属的反应结果都大不相同。对于Mn，将等摩尔量的酸加到去质子化产物中可得到N-杂环卡宾（NHC）络合物，而对于Re，一旦中心咪唑CH基团发生了去质子化，联吡啶配体就会经历对邻位碳的亲核攻击，提供CC偶联产物。这些研究扩展到伪八面体[Mo（η〜3-烯丙基）（双吡啶）（CO）_2（N-RIm）]〜+配合物使我们能够分离阳离子NHC配合物（Mn I型行为），以及它们的中性咪唑-2-基前体。对[Mn（bipy）（CO）_3（N-PhIm）]〜+，[Re（bipy）（CO）_3（N-MesIm）]〜的质子化进行了DFT计算，对反应机理进行了理论研究。 +和B_3LYP / 6-31G（d）处的[Mo（η〜3-C4H7）（bipy）（CO）_2（N-MesIm）]〜+复合物（Mes = mesityl）（对于锰，Re，和Mo）的理论水平。我们的结果解释了为什么在实验中发现了锰，钼和Re配合物不同的产品。对于Re，形成C-C偶联产物的过程显然比形成咪唑-2-基产物的过程更受青睐。相比之下，对于Mn和Mo络合物，中心咪唑和邻位Bipy C原子之间较低的稳定相互作用以及较高的配体不稳定性，使得从动力学上更容易获得NHC型产物的形成，这与实验相吻合。发现。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号