Shibata Yu, Nagae Haruki, Sumiya Shiki, Rochat Raphaël, Tsurugi Hayato, Mashima Kazushi
Department of Chemistry , Graduate School of Engineering Science , Osaka University , Toyonaka , Osaka 560-8531 , Japan . Email:
Chem Sci. 2015 Oct 1;6(10):5394-5399. doi: 10.1039/c5sc01599e. Epub 2015 Jul 17.
An alkylyttrium complex supported by an ,'-bis(2,6-diisopropylphenyl)ethylenediamido ligand, (ArNCHCHNAr)Y(CHSiMe)(THF) (, Ar = 2,6- PrCH), activated an -phenyl C-H bond of 2-phenylpyridine () to form a (2-pyridylphenyl)yttrium complex () containing a five-membered metallacycle. Subsequently, a unique C(sp)-C(sp) coupling of 2-phenylpyridine proceeded through a bimetallic yttrium intermediate, derived from an intramolecular shift of the yttrium center to an -position of the pyridine ring in , to yield a bimetallic yttrium complex () bridged by two-electron reduced 6,6'-diphenyl-2,2'-bipyridyl. Aryl substituents at the -position of the pyridine ring were key in order to destabilize the μ,κ-(C,N)-pyridyldiyttrium intermediate prior to the C(sp)-C(sp) bond formation.
由一个η²,η²-双(2,6-二异丙基苯基)乙二胺配体支撑的烷基钇配合物,(ArNCH₂CH₂NAr)Y(CH₂SiMe₃)(THF)(其中,Ar = 2,6-i-Pr₂C₆H₃),活化了2-苯基吡啶( )的α-苯基C-H键,形成了一个含有五元金属环的(2-吡啶基苯基)钇配合物( )。随后,2-苯基吡啶独特的C(sp²)-C(sp³)偶联通过一个双金属钇中间体进行,该中间体源自钇中心向 中吡啶环的α-位的分子内迁移,生成了一个由双电子还原的6,6'-二苯基-2,2'-联吡啶桥连的双金属钇配合物( )。吡啶环α-位的芳基取代基是关键,以便在C(sp²)-C(sp³)键形成之前使μ,κ-(C,N)-吡啶基二钇中间体不稳定。