Competitive Activation of N−C and C−H Bonds of the PNP Framework by Monovalent Rhodium and Iridium
作者:Wei Weng、Chengyun Guo、Claudia Moura、Lin Yang、Bruce M. Foxman、Oleg V. Ozerov
DOI:10.1021/om050346o
日期:2005.7.1
This work describes how reactions of oxidative addition of N−C and C−H bonds are in competition in the PNP-ligated Rh and Ir complexes. Iridium appears to have a higher preference than Rh for the C−H activation over the N−C activation, and the Ir C−H activated complexes are more kinetically stable than their Rh analogues. A new generation of a diarylamido-based PNP pincer is presented, a “tied” PNP
这项工作描述了N-C和C-H键的氧化加成反应在PNP连接的Rh和Ir络合物中如何竞争。铱似乎比Rh具有更高的优先权,其CH活化作用优于Nc活化作用,并且Ir CH活化的络合物比Rh的类似物在动力学上更稳定。提出了新一代的基于二芳基酰胺的PNP钳,一种基于亚氨基二苄基亚结构的“并列” PNP配体1c。该配体被更明确地预定为以子午线,阴离子PNP方式与金属中心结合。结果,它的N-C裂解反应(导致阴离子PNP的络合物)比“未结合”的配体1a,b更快。结构证据表明,当受主原子构象的影响时,在供体原子上带有相同的取代基时,“并列”阴离子PNP钳形配体比“未并列”配体更大。“并列”的钳形配体还允许观察中心N-CH 3基团的CH键的激活产物,而“未并列”的配体未检测到。与“未结合”配体的NC氧化加成反应以固态以及在溶液中进行。据报道,固态N-C氧化加成反应比溶液反应具有更高的选择性,结果显着。通过同位素标记(2