Tunneling control of chemical reactions: C–H insertion versus H-tunneling in tert-butylhydroxycarbene
作者:David Ley、Dennis Gerbig、Peter R. Schreiner
DOI:10.1039/c2sc21555a
日期:——
and 31.0 kcal mol−1, respectively. Once embedded in the cold Ar matrix, the carbene transforms to its isomer pivaldehyde not only by photolysis, but it also cuts through the barrier of 27.3 kcal mol−1 by quantum mechanical tunneling. The temperature independent half-life is measured as 1.7 h; the tunneling pathway was entirely blocked upon O-deuteration. The experimental half-life of tert-butylhydroxycarbene
通过气相的高真空闪速热解生成了难以捉摸的叔丁基羟基卡宾叔丁基乙醛酸在960°C下。随后将热解产物矩阵于11 K在固体Ar中分离,并通过红外光谱进行表征。羟基卡宾在仍处于苛刻的热解条件下时会经历CH插入二甲基环丙醇,以及对新型甲基丁烯醇的CC插入,其激活势垒分别为23.8和31.0 kcal mol -1。一旦嵌入冷氩气中矩阵卡宾不仅通过光解转变为异构体四乙醛,而且通过量子机械隧穿也突破了27.3 kcal mol -1的势垒。与温度无关的半衰期为1.7小时;O-氘化完全阻断了隧道通道。叔丁基羟基卡宾的实验半衰期通过Wentzel-Kramers-Brillouin形式主义在计算上可行的M06-2X / 6-311 ++ G(d,p)理论水平上评估的最小能量路径上的隧穿计算得到了验证。我们的实验结果得到了CCSD(T)/ cc-pVDZ理论水平的相对能量计算的支持。