Aromaticity

Evaluating the aromaticity of a molecular system and the influence of this concept on its properties is a crucial step in the development of novel aromatic systems. Modern computational methods can provide researchers with a high level of insight into such aromaticity, but identifying the most appropriate method for assessing a specific system can prove difficult. Aromaticity: Modern Computational Methods and Applications reviews the latest state-of-the-art computational methods in this field and discusses their applicability for evaluating the aromaticity of a system. In addition to covering aromaticity for typical organic molecules, this volume also explores systems possessing transition metals in their structures, macrocycles and even transition structures. The influence of the aromaticity on the properties of these species (including the structure, magnetic properties and reactivity) is highlighted, along with potential applications in fields including materials science and medicinal chemistry. Finally, the controversial and fuzzy nature of aromaticity as a concept is discussed, providing the basis for an updated and more comprehensive definition of this concept. Drawing on the knowledge of an international team of experts, Aromaticity: Modern Computational Methods and Applications is a unique guide for anyone researching, studying or applying principles of aromaticity in their work, from computational and organic chemists to pharmaceutical and materials scientists. Reviews a range of computational methods to assess the aromatic nature of different compounds, helping readers select the most useful tool for the system they are studying Presents a complete guide to the key concepts and fundamental principles of aromaticity Provides guidance on identifying which variables should be modified to tune the properties of an aromatic system for different potential applications

Heterocyclic chemistry is the biggest branch of chemistry covering two-thirds of the chemical literature. Aromaticity in Heterocyclic Compounds covers hot topics of frontier research summarized by reputed scientists in the field.

Aromaticity and Antiaromaticity A comprehensive review of the science of aromaticity, as well as its evolution, from benzene to atomic clusters In Aromaticity and Antiaromaticity: Concepts and Applications, a team of accomplished chemists delivers a comprehensive exploration of the evolution and critical aspects of aromaticity. The book examines the new global criteria used to evaluate aromaticity, including the Nucleus Independent Chemical Shift (NICS) index and the electronic indices based on electronic properties. Additional discussions of inorganic aromatic compounds developed in this century, which give rise to new concepts like multifold aromaticity, are included. Three-dimensional aromaticity found in fullerenes and nanotubes, Möbius aromaticity present in some annulenes, and excited state aromaticity are explored as well. This volume explores the geometrical, electronic, magnetic, and thermodynamic characteristics of aromatic and antiaromatic compounds and their reactivity properties. It also provides: A thorough historical overview of aromaticity, as well as simple electronic and structural models Comprehensive explorations of organic and inorganic aromatic compounds, concepts of stability and reactivity, and geometric, energetic, magnetic, and electronic criteria of descriptors of aromaticity Practical discussions of heteroaromaticity, as well as Möbius aromaticity and excited state aromaticity In-depth examinations of sigma, pi, delta, and phi aromaticity Perfect for graduate students, researchers, and academics interested in aromaticity, organometallic chemistry, and computational chemistry, Aromaticity and Antiaromaticity: Concepts and Applications will also earn a place in the libraries of professionals and researchers working in organic, inorganic, and physical chemistry.

Metal clusters, an intermediate state between molecules and the extended solid, show peculiar bonding and reactivity patterns. Their significance is critical to many areas, including air pollution, interstellar matter, clay minerals, photography, catalysis, quantum dots, and virus crystals. In Aromaticity and Metal Clusters, dozens of international experts explore not only the basic aspects of aromaticity, but also the structures, properties, reactivity, stability, and other consequences of the aromaticity of a variety of metal clusters. Although the concept of aromaticity has been known for nearly two centuries, there is no way to measure it experimentally and no theoretical formula to calculate it. In order to gain insight into its exact nature, the authors of this volume examine various indirect characteristics such as geometrical, electronic, magnetic, thermodynamic, and reactivity considerations. The book begins by discussing the evolution of aromaticity from benzene to atomic clusters. Next, more specialized chapters focus on areas of significant interest. Topics discussed include: Computational studies on molecules with unusual aromaticity Electronic shells and magnetism in small metal clusters A density functional investigation on the structures, energetics, and properties of sodium clusters through electrostatic guidelines and molecular tailoring The correlation between electron delocalization and ring currents in all metallic aromatic compounds Phenomenological shell model and aromaticity in metal clusters Rationalizing the aromaticity indexes used to describe the aromatic behavior of metal clusters 5f orbital successive aromatic and antiaromatic zones in triangular uranium cluster chemistry This collection of diverse contributions, composed of the work of scientists worldwide, is destined to not only answer puzzling questions about the nature of aromaticity, but also to provoke further inquiry in the minds of researchers.

Examines aromaticity through the historical and conceptual framework of simple molecular orbital theory. This approach is unique in that theoretical considerations are integrated with experimental observations. The criteria for aromatic, antiaromatic and nonaromatic compounds are discussed in with reference to benzene, cyclobutadiene and cyclooctatetraene. Also includes a chapter on the likely classes of aromatic compounds.

Designed to assist chemists in integrating the results of calculations on molecules and ions into their general body of chemical knowledge. Contains recent contributions from theoretical and computational chemistry to the development of the concept of aromaticity (antiaromaticity) and its expansion into new areas such as organometallic and cluster compounds and three-dimensional structures. Updates the modern status of aromaticity and covers basic principles and experimental applications.