Computational methods for contemporary carbene chemistry

Abstract

The use of computational methods in carbene chemistry has a long-standing tradition. Indeed, the field has come a long way since the first ab initio calculations on methylene. Computations now routinely accompany most experimental studies, either to validate the obtained results or to help design appropriate experiments. Advances in computational carbene chemistry within the last decade are covered in this text, encompassing a plethora of studies on alkyl-, aryl-, halo-, and heterocarbenes (N, P, O, S) as well as on persistent triplet carbenes. Moreover, the conceptual advancements in the fields of theoretical chemistry and computing technology have enabled researchers to conduct intricate ab initio studies. The application of leading-edge theory to multireference problems, high-accuracy thermochemical evaluations, atom tunneling, and the description of bonding is thoroughly reviewed. In addition, general recommendations for the choice of an appropriate method for a specific computational problem are given. Practitioners of the art are likely to discover new computational approaches in carbene chemistry applied to various examples from the current literature. C 2012 John Wiley & Sons, Ltd.

Mechanisms Revealed Through General Anesthetic Photolabeling

“…A singlet carbene is a neutral divalent carbon species having an empty p -orbital and a hybrid orbital that contains two paired valence electrons [25]. By virtue of this electronic arrangement, the carbene intermediate simultaneously displays carbocation and carbanion characteristics, allowing both electrophilic and nucleophilic reactions, and enabling covalent attachment to proteins orders-of-magnitude faster than carbon-centered radicals (e.g., chlorotrifluoroethyl radical) [26,27]. While initially formed in the singlet state, many carbenes will convert to a triplet state that has one electron of the same spin in the two valence orbitals.…”

Photoelimination of nitrogen from adamantane and pentacycloundecane (PCU) diazirines: a spectroscopic study and supramolecular control †

“…In order to further rationalize the observed experimental results, we performed theoretical studies dealing with the properties of diazirines 1 and 2 as well as the corresponding diazo intermediates 14 and 7 and carbenes 15 and 8. Since choosing a suitable approach for computing carbene structures is not a trivial matter, 52 we decided on a recently developed DFT method that was already used for polycyclic carbenes. 21 More specifically, we chose a MN12-SX/6-311+G(d) level of theory that was successfully applied for describing 2adamantylidene (8) reactivity and its nucleophilic character toward alkenes.…”

Molecular dynamics out of equilibrium: mechanics and measurables

“…The critical challenge all of these methods face is an accounting of the complicated structure of electron correlation integrals. Dozens of open source and commercial quantum chemistry computer programs are developed for use in computational chemistry . These methods allow one to obtain potentials with high accuracy but are generally not suitable for implementation within MD calculations due to their high time and computational resource cost, especially for simulations involving many large molecules.…”