Photochemistry of 2,2,4,4-Tetramethyl-3-thietan-1-ylidene: A Heterocyclic Carbene with an Unusually Short Lifetime and Evidence for a Nonclassical Structure
作者:John R. Snoonian、Matthew S. Platz
DOI:10.1021/jp0016840
日期:2001.3.1
Laser flash (308 nm) and steady-state photolysis (300 nm) of Δ3-1,3,4-oxadiazoline (3) produces a transient that can be trapped with pyridine to give an adduct with λmax = 350 nm, attributed to ylide 10. Laser flash photolysis (LFP) studies of the ylide indicate that the value of kpyrτ (where kpyr is the absolute rate constant of carbene reaction with pyridine and τ is the carbene lifetime) of the
激光闪光 (308 nm) 和 Δ3-1,3,4-恶二唑啉 (3) 的稳态光解 (300 nm) 产生一个瞬态,该瞬态可以被吡啶捕获,得到 λmax = 350 nm 的加合物,归因于叶立德10. 叶立德的激光闪光光解 (LFP) 研究表明,活性中间体的 kpyrτ 值(其中 kpyr 是卡宾与吡啶反应的绝对速率常数,τ 是卡宾寿命)比推导出的值小 25 倍亚环丁基。含硫瞬态的寿命可能比环丁叉短得多或kpyr 值小得多。这些实验结果以及从头算计算表明,2,2,4,4-tetramethyl-3-thietan-1-ylidene 的结构最好表示为非经典二等分结构 2,而不是经典结构 1。