A scheme that reduces the calculations of ground-state properties of systems of interacting particles exactly to the solution of single-particle Hartree-type equations has obvious advantages. It is not surprising, then, that the density functional formalism, which provides a way of doing this, has received much attention in the past two decades. The quality of the energy surfaces calculated using a simple local-density approximation for exchange and correlation exceeds by far the original expectations. In this work, the authors survey the formalism and some of its applications (in particular to atoms and small molecules) and discuss the reasons for the successes and failures of the local-density approximation and some of its modifications.

The density functional formalism, its applications and prospects

N-Heterocyclic Carbenes in Late Transition Metal Catalysis

The halogen bond occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity. In this fairly extensive review, after a brief history of the interaction, we will provide the reader with a snapshot of where the research on the halogen bond is now, and, perhaps, where it is going. The specific advantages brought up by a design based on the use of the halogen bond will be demonstrated in quite different fields spanning from material sciences to biomolecular recognition and drug design.

The Halogen Bond

Since the discovery of organic azides by Peter Griess more than 140 years ago, numerous syntheses of these energy-rich molecules have been developed. In more recent times in particular, completely new perspectives have been developed for their use in peptide chemistry, combinatorial chemistry, and heterocyclic synthesis. Organic azides have assumed an important position at the interface between chemistry, biology, medicine, and materials science. In this Review, the fundamental characteristics of azide chemistry and current developments are presented. The focus will be placed on cycloadditions (Huisgen reaction), aza ylide chemistry, and the synthesis of heterocycles. Further reactions such as the aza-Wittig reaction, the Sundberg rearrangement, the Staudinger ligation, the Boyer and Boyer-Aube rearrangements, the Curtius rearrangement, the Schmidt rearrangement, and the Hemetsberger rearrangement bear witness to the versatility of modern azide chemistry.

Organic Azides: An Exploding Diversity of a Unique Class of Compounds

The review covers the knowledge on photoremovable protecting
groups and includes all relevant chromophores studied in the
time period of 2000–2012; the most relevant earlier works are
also discussed.

/pdf/photoremovable-protecting-groups-in-chemistry-and-biology-2n33qs6p7b.pdf

Photoremovable Protecting Groups in Chemistry and Biology: Reaction Mechanisms and Efficacy

The thermal reaction of ozone with trimethyl aluminum was explored using twin jet, concentric jet, and merged jet deposition into cryogenic matrixes. Infrared spectroscopy and density functional theory calculations were employed to identify and characterize the products formed in each case. Together, these deposition techniques provide information over the essentially full course of the gas-phase reaction. At short times with twin jet deposition, the primary product is the O atom insertion product (CH3)2AlOCH3. With merged jet deposition and longer gas-phase mixing times, the methyl peroxy radical H3COO· was seen in good yield along with final stable products H2CO, H3COH, and C2H6. Production of Al2O3 and its deposition onto the walls of the reaction tube as a powdery film was noted as well. All of these outcomes were combined to propose a reaction mechanism for this system. Of particular note, the observation of H3COO· provides clear evidence for a free radical component to the overall mechanism.

Matrix Isolation Studies of Novel Intermediates in the Reaction of Trimethylaluminum with Ozone.

Matrix isolation investigation of the methylfluorosilicate anions

The thermal and photochemical reactions of ozone with ruthenocene were studied in argon matrices at 10–15 K by infrared spectroscopy. Irradiation of freshly deposited matrices with near-infrared light (λ = 880 nm) from an LED resulted in new peaks in their infrared spectra that were assigned to three new ruthenocene oxide structures (4, 5, and 6) calculated by the density functional theory. It is proposed that the near-infrared light caused photodissociation of some ozone molecules and subsequent reactions of the atomic oxygen produced with adjacent ruthenocene molecules in the matrix. Structures 4 and 5 contain a Ru=O oxo group resulting from the attack of atomic oxygen on the ruthenium atom, and structure 6 contains a C=O aldehyde group resulting from the attack of atomic oxygen on a ring carbon atom. Subsequent irradiation of the matrix with red light (λ = 625 nm) from an LED resulted in a fourth new structure (7), and it also initiated a reversible photochemical conversion 4 ⇄ 5 + O2, with the forward...

Bruce S. Ault

Papers

Matrix Isolation Studies of Novel Intermediates in the Reaction of Trimethylaluminum with Ozone.

Matrix isolation investigation of the methylfluorosilicate anions

Infrared Matrix-Isolation and Theoretical Study of the Reactions of Ruthenocene with Ozone

Laser photoluminescence of iodine matrix samples: Spectroscopic evidence for several (I2)2 species

Matrix isolation infrared spectroscopic study of the interaction of CH3ReO3 with NH3.