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.

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

Matrix-isolation studies of Lewis acid-base interactions. 2. 1/1 Adduct of tetrafluorosilane with methyl-substituted amines

Infrared matrix isolation study of the reaction of CrCl2O2 with (CH3)2O and (CH3)2CO

The matrix isolation technique has been combined with infrared spectroscopy to isolate, identify, and characterize the initial intermediates in the thermal and photochemical reactions of OVCl3 with CH3SH. The thermal reaction proceeds through formation of a 1:1 complex that is characterized by perturbations to the −VCl3, −VO, and S−H stretching modes, as well as the −CH3 rocking and bending modes. The photochemical reaction leads to HCl elimination from the initial 1:1 complex, and formation of Cl2V(O)SCH3. Additional support for the species identification and vibrational band assignments comes from isotopic substitution. Density functional calculations (B3LYP/6-311G+(d, 2p)) were carried out to confirm the experimental band assignments for this latter species. Efforts to study the thermal reaction beyond formation of the initial complex were unsuccessful, despite pyrolysis at temperatures as high as 300 °C prior to sample deposition.

Bruce S. Ault

Papers

Matrix-isolation studies of Lewis acid-base interactions. 2. 1/1 Adduct of tetrafluorosilane with methyl-substituted amines

Infrared matrix isolation study of the reaction of CrCl2O2 with (CH3)2O and (CH3)2CO

Matrix Isolation and Density Functional Study of the Reaction of OVCl3 with CH3SH

Infrared matrix isolation studies of the reactions of F2 with sulfur and phosphorus bases

Matrix isolation study of the interaction of HCl with CrCl2O2 and OVCl3