Lester Andrews

Bio: Lester Andrews is an academic researcher from University of Virginia. The author has contributed to research in topic(s): Infrared spectroscopy & Molecule. The author has an hindex of 68, co-authored 888 publication(s) receiving 24613 citation(s). Previous affiliations of Lester Andrews include Ames Research Center & Environmental Molecular Sciences Laboratory.

Reactions of boron atoms with molecular oxygen. Infrared spectra of BO, BO2, B2O2, B2O3, and BO−2 in solid argon

Abstract: Boron atoms from Nd:YAG laserablation of the solid have been codeposited with Ar/O2 samples on a 11±1 K salt window. The product infrared spectrum was dominated by three strong 11B isotopic bands at 1299.3, 1282.8, and 1274.6 cm− 1 with 10B counterparts at 1347.6, 1330.7, and 1322.2 cm− 1. Oxygen isotopic substitution (16O18O and 18O2 ) confirms the assignment of these strong bands to ν3 of linear BO2. Renner–Teller coupling is evident in the ν2 bending motion. A sharp medium intensity band at 1854.7 has appropriate isotopic ratios for BO, which exhibits a 1862.1 cm− 1 gas phase fundamental. A sharp 1931.0 cm− 1 band shows isotopic ratios appropriate for another linear BO2 species; correlation with spectra of BO− 2 in alkali halide lattices confirms this assignment. A weak 1898.9 cm− 1 band grows on annealing and shows isotopic ratios for a BO stretching mode and isotopic splittings for two equivalent B and O atoms, which confirms assignment to B2O2. A weak 2062 cm− 1 band grows markedly on annealing and shows isotope shifts appropriate for a terminal–BO group interacting with another oxygen atom; the 2062 cm− 1 band is assigned to B2O3 in agreement with earlier work. A strong 1512.3 cm− 1 band appeared on annealing; its proximity to the O2 fundamental at 1552 cm− 1 and pure oxygen isotopic shift suggest that this absorption is due to a B atom–O2 complex.

Spectroscopic and theoretical studies of transition metal oxides and dioxygen complexes.

Abstract: 3.1. Sc Group 6772 3.2. Ti Group 6773 3.3. V Group 6775 3.4. Cr Group 6776 3.5. Mn Group 6777 3.6. Fe Group 6779 3.7. Co Group 6780 3.8. Ni Group 6782 3.9. Cu Group 6782 3.10. Zn Group 6784 3.11. Lanthanide Group 6784 3.12. Actinide Group 6785 3.13. Periodic Trends on Bonding and Reactivity 6785 4. Ionic Mononuclear Transition Metal Oxide Species 6787 4.1. Cations 6788 4.2. Anions 6790 4.2.1. Monoxide Anions 6790 4.2.2. Dioxide Anions 6791 4.2.3. Oxygen-Rich Anions 6792 5. Multinuclear Transition Metal Oxide Clusters 6792 5.1. Sc Group 6793 5.2. Ti Group 6793 5.3. V Group 6793 5.4. Cr Group 6797 5.5. Mn Group 6798 5.6. Fe Group 6798 5.7. Co Group 6798 5.8. Ni Group 6798 5.9. Cu Group 6799 6. Summary 6800 7. Acknowledgments 6800 8. References 6800

Noble gas-actinide compounds: complexation of the CUO molecule by Ar, Kr, and Xe atoms in noble gas matrices.

Abstract: The CUO molecule, formed from the reaction of laser-ablated U atoms with CO in a noble gas, exhibits very different stretching frequencies in a solid argon matrix [804.3 and 852.5 wave numbers (cm−1)] than in a solid neon matrix (872.2 and 1047.3 cm−1). Related experiments in a matrix consisting of 1% argon in neon suggest that the argon atoms are interacting directly with the CUO molecule. Relativistic density functional calculations predict that CUO can bind directly to one argon atom (U-Ar = 3.16 angstroms; binding energy = 3.2 kilocalories per mole), accompanied by a change in the ground state from a singlet to a triplet. Our experimental and theoretical results also suggest that multiple argon atoms can bind to a single CUO molecule.

OCBBCO: A neutral molecule with some boron-boron triple bond character

Abstract: Molecules that contain boron−boron multiple bonds are extremely rare due to the electron-deficient nature of boron. Here we report experimental and theoretical evidence of a neutral OCBBCO molecule with some boron−boron triple bond character. The molecule was produced and unambiguously characterized by matrix isolation infrared spectroscopy. Quantum chemical calculations indicate that the molecule has a linear singlet ground state with a very short boron−boron bond length.

A Chemist's Guide to Density Functional Theory

Abstract: "Chemists familiar with conventional quantum mechanics will applaud and benefit greatly from this particularly instructive, thorough and clearly written exposition of density functional theory: its basis, concepts, terms, implementation, and performance in diverse applications. Users of DFT for structure, energy, and molecular property computations, as well as reaction mechanism studies, are guided to the optimum choices of the most effective methods. Well done!" Paul von RaguE Schleyer "A conspicuous hole in the computational chemist's library is nicely filled by this book, which provides a wide-ranging and pragmatic view of the subject.[...It] should justifiably become the favorite text on the subject for practioneers who aim to use DFT to solve chemical problems." J. F. Stanton, J. Am. Chem. Soc. "The authors' aim is to guide the chemist through basic theoretical and related technical aspects of DFT at an easy-to-understand theoretical level. They succeed admirably." P. C. H. Mitchell, Appl. Organomet. Chem. "The authors have done an excellent service to the chemical community. [...] A Chemist's Guide to Density Functional Theory is exactly what the title suggests. It should be an invaluable source of insight and knowledge for many chemists using DFT approaches to solve chemical problems." M. Kaupp, Angew. Chem.

The density functional formalism, its applications and prospects

Abstract: 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 Halogen Bond

Abstract: 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.

Frustrated Lewis pairs: metal-free hydrogen activation and more.

Abstract: Sterically encumbered Lewis acid and Lewis base combinations do not undergo the ubiquitous neutralization reaction to form "classical" Lewis acid/Lewis base adducts. Rather, both the unquenched Lewis acidity and basicity of such sterically "frustrated Lewis pairs (FLPs)" is available to carry out unusual reactions. Typical examples of frustrated Lewis pairs are inter- or intramolecular combinations of bulky phosphines or amines with strongly electrophilic RB(C(6)F(5))(2) components. Many examples of such frustrated Lewis pairs are able to cleave dihydrogen heterolytically. The resulting H(+)/H(-) pairs (stabilized for example, in the form of the respective phosphonium cation/hydridoborate anion salts) serve as active metal-free catalysts for the hydrogenation of, for example, bulky imines, enamines, or enol ethers. Frustrated Lewis pairs also react with alkenes, aldehydes, and a variety of other small molecules, including carbon dioxide, in cooperative three-component reactions, offering new strategies for synthetic chemistry.

Thermal decomposition of the non-interstitial hydrides for the storage and production of hydrogen.

Abstract: This review focuses on key aspects of the thermal decomposition of multinary or mixed hydride materials, with a particular emphasis on the rational control and chemical tuning of the strategically important thermal decomposition temperature of such hydrides, Tdec. An attempt is also made to predict the thermal stability of as-yet unknown, elusive or even unknown hydrides. The future of a particularly promising class of materials for hydrogen storage, namely the catalytically enhanced complex metal hydrides, is discussed. The predictions are supported by thermodynamics considerations, calculations derived from molecular orbital (MO) theory and backed up by simple chemical insights and intuition.