Tunneling in novel hydroxycarbenes

基于吉森的互补背景和专业知识（实验有机化学家和光谱学家）和布达佩斯（计算量子化学家）小组，我们提出了一个联合计划，独特地结合了准备，检测，设计的新型卡宾在低温下在大势垒下表现出增强的氢和可能的重原子隧穿，（降到6 K）。低温基质的极低温度和惰性气体环境非常适合单基态表面上的量子化学反应速率和隧道效应（量子反应动力学）研究。所提出的全维和降维反应动力学计算预计将指导新的实验，当增加了复杂的电子结构计算，应该阐明的因素，管理增强量子力学隧道下的大障碍近0 K的时间尺度上的分钟到天。拟议的研究旨在回答的问题包括：（a）电子取代基效应如何改变新的不饱和羟基卡宾的H-隧道的速率;（B）多大的障碍可以提供可观察的H-隧道;（c）氢键可以用来调整H-隧道的速率？ 拟议的研究计划的新方面包括：（a）系统地制备一系列电子相关的取代的、目前未知的羟基卡宾;（B）开发取代羟基卡宾的合成路线;（c）利用最先进的量子化学水平研究电子效应对隧道效应的影响（包括突破性的电子结构、核运动和反应动力学计算）;（d）含有五个或更多个原子和/或其PES上的多个极小值的卡宾的转振光谱的变分确定;（e）基于与时间无关的机制的可用性的微正则速率常数的量子化学计算，该机制类似于允许确定几乎完整的一组固定的旋转-振动波函数和能级的机制。

Building on the complementary backgrounds and expertise of the Giessen (experimental organic chemists and spectroscopists) and the Budapest (computational quantum chemists) groups, we propose a joint program that uniquely combines the preparation, detection, and spectroscopic as well as computa-tional characterization of designed novel carbenes exhibiting enhanced hydrogen and possibly heavy-atom tunnelling under large barriers at low cryogenic temperatures (down to 6 K). The very low temperatures and the noble gas environment of cryogenic matrices are ideally suited for quantum chemical reaction rate and tunnelling (quantum reaction dynamics) studies on single ground-state surfaces. The proposed full- and reduced-dimensionality reaction dynamics computations are expected to guide new experiments and, when augmented with sophisticated electronic structure computations, should shed light on the factors that govern enhanced quantum mechanical tunnelling under large barriers near 0 K on timescales of minutes to days. Questions the proposed research aims to answer include: (a) how do electronic substituent effects alter the rates of H-tunnelling in novel unsaturated hydroxycarbenes; (b) how large a barrier can be afforded for observable H-tunnelling; and (c) can hydrogen bonding be used to tune the rate of H-tunneling? Novel aspects of the proposed research program include: (a) systematic preparation of a series of electronically related substituted, currently unknown hydroxycarbenes; (b) development of synthetic routes to substituted hydroxycarbenes; (c) studying the electronic effects on tunnelling, utilizing the most advanced levels of quantum chemistry (including ground-breaking electronic structure, nuclear motion, and reaction dynamics computations); (d) variational determination of rovibrational spectra of carbenes containing five or more atoms and/or multiple minima on their PES; (e) quantum chemical computation of microcanonical rate constants based on the availability based on a time-independent machinery similar to that which allows determination of a nearly complete set of stationary rotational-vibrational wave functions and energy levels.