There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

The relatively small diffuse function-augmented basis set, 3-21+G, is shown to describe anion geometries and proton affinities adequately. The diffuse sp orbital exponents are recommended for general use to augment larger basis sets.

Efficient diffuse function‐augmented basis sets for anion calculations. III. The 3‐21+G basis set for first‐row elements, Li–F

A. Water Exchange 2326 B. Proton Exchange 2327 C. Electronic Relaxation 2327 D. Relaxivity 2331 E. Outerand Second-Sphere Relaxivity 2334 F. Methods of Improving Relaxivity 2336 V. Macromolecular Conjugates 2336 A. Introduction 2336 B. General Conjugation Methods 2336 C. Synthetic Linear Polymers 2336 D. Synthetic Dendrimer-Based Agents 2338 E. Naturally Occurring Polymers (Proteins, Polysaccharides, and Nucleic Acids) 2339

https://mriquestions.com/uploads/3/4/5/7/34572113/lauffer_1999_review.pdf

Gadolinium(III) Chelates as MRI Contrast Agents: Structure, Dynamics, and Applications

I. Introduction: Conceptual vs Fundamental andComputational Aspects of DFT1793II. Fundamental and Computational Aspects of DFT 1795A. The Basics of DFT: The Hohenberg−KohnTheorems1795B. DFT as a Tool for Calculating Atomic andMolecular Properties: The Kohn−ShamEquations1796C. Electronic Chemical Potential andElectronegativity: Bridging Computational andConceptual DFT1797III. DFT-Based Concepts and Principles 1798A. General Scheme: Nalewajski’s ChargeSensitivity Analysis1798B. Concepts and Their Calculation 18001. Electronegativity and the ElectronicChemical Potential18002. Global Hardness and Softness 18023. The Electronic Fukui Function, LocalSoftness, and Softness Kernel18074. Local Hardness and Hardness Kernel 18135. The Molecular Shape FunctionsSimilarity 18146. The Nuclear Fukui Function and ItsDerivatives18167. Spin-Polarized Generalizations 18198. Solvent Effects 18209. Time Evolution of Reactivity Indices 1821C. Principles 18221. Sanderson’s Electronegativity EqualizationPrinciple18222. Pearson’s Hard and Soft Acids andBases Principle18253. The Maximum Hardness Principle 1829IV. Applications 1833A. Atoms and Functional Groups 1833B. Molecular Properties 18381. Dipole Moment, Hardness, Softness, andRelated Properties18382. Conformation 18403. Aromaticity 1840C. Reactivity 18421. Introduction 18422. Comparison of Intramolecular ReactivitySequences18443. Comparison of Intermolecular ReactivitySequences18494. Excited States 1857D. Clusters and Catalysis 1858V. Conclusions 1860VI. Glossary of Most Important Symbols andAcronyms1860VII. Acknowledgments 1861VIII. Note Added in Proof 1862IX. References 1865

/pdf/conceptual-density-functional-theory-btz9wwrxv9.pdf

Conceptual density functional theory.

Asymmetric enamine catalysis.

The lithium salts, LiClO 4 and LiBF 4 , have been investigated for their potential use as Lewis acid catalysts in the intramolecular Diels-Alder reaction. No cycloaddition of the trienone, 1 , is observed when LiClO 4 is used. LiBF 4 provides quantitative yield of the cis -fused cycloadduct in 72 hours at room temperature. The catalysis is ascribed to the slow release of BF 3 rather than to the lithium cation.

LiBF4: A Mild Lewis Acid for Intramolecular Diels-Alder Reactions.

[2+2+2]-Cycloreversion reactions of cyclohexane and ten fused cyclohexanes were studied computationally with B3LYP/6-31G* and CASSCF methods. Reactions involving cleavage of bonds in three- and five-membered rings show distinctly lower barriers to cycloreversion than cleavage of four-membered rings. The lower activation energies for the cleavage of odd-membered rings arise from interactions of the sigma framework of the odd-membered ring with the orbitals of the breaking bond. NICS values were calculated to determine the aromaticity of the different rings involved in bond cleavage. In addition to concerted mechanisms, the stepwise diradical pathways for the [2+2+2]-cycloreversions of cyclohexane and cis-tris-cyclopropacyclohexane were studied.

[2 + 2 + 2]-Cycloreversion Reactions: A Theoretical Elucidation of Thermodynamic and Through-Bond Coupling Effects on Activation Energies.

This study proves Wanbin Zhang's finding that weak attractive interactions between substrate and ligand play an important role in metal-catalyzed asymmetric hydrogenations and shows that the dispersion interaction is the major attractive interaction.

K. N. Houk

Papers

LiBF4: A Mild Lewis Acid for Intramolecular Diels-Alder Reactions.

[2 + 2 + 2]-Cycloreversion Reactions: A Theoretical Elucidation of Thermodynamic and Through-Bond Coupling Effects on Activation Energies.

The role of attractive dispersion interaction in promoting the catalytic activity of asymmetric hydrogenation

Synergistic Effects Between Lewis and Broensted Acids: Application to the Prins Cyclization.