High Resolution NMR Spectroscopy: Understanding Molecules and their Electronic Structures

High Resolution NMR Spectroscopy: Understanding Molecules and their Electronic Structures
  • Author : Anonim
  • Publisher : Newnes
  • Release : 08 June 2013
GET THIS BOOKHigh Resolution NMR Spectroscopy: Understanding Molecules and their Electronic Structures

The progress in nuclear magnetic resonance (NMR) spectroscopy that took place during the last several decades is observed in both experimental capabilities and theoretical approaches to study the spectral parameters. The scope of NMR spectroscopy for studying a large series of molecular problems has notably broadened. However, at the same time, it requires specialists to fully use its potentialities. This is a notorious problem and it is reflected in the current literature where this spectroscopy is typically only used in

Advanced Functional Materials

Advanced Functional Materials
  • Author : Biplab Sanyal,Olle Eriksson
  • Publisher : Newnes
  • Release : 24 June 2021
GET THIS BOOKAdvanced Functional Materials

This book deals with functional materials that are in the frontiers of current materials science and technology research, development and manufacture. The first of its kind, it deals with three classes of materials, (1) magnetic semiconductors, (2) multiferroics, and (3) graphene. Because of the wide popularity of these materials there is a strong need for a book about these materials for graduate students, new researchers in science and technology, as well as experienced scientists and technologists, technology based companies and government institutes for

High Resolution NMR Spectroscopy

High Resolution NMR Spectroscopy
  • Author : Gustavo A. Aucar,Martin C. Ruiz de Azúa,Claudia G. Giribet
  • Publisher : Elsevier Inc. Chapters
  • Release : 08 June 2013
GET THIS BOOKHigh Resolution NMR Spectroscopy

Polarization propagators (PP) are powerful theoretical tools that allow carrying out a deep analysis of the electronic mechanisms underlying any molecular response property. The inner projections of the PP and contributions from localized orbitals within the PP approaches described in were developed to fully take advantage of this power of analysis for the study of NMR spectroscopic parameters. They are based on the use of localized molecular orbitals (LMOs) related to chemically intuitive concepts to decompose the mathematical expression of

High Resolution NMR Spectroscopy

High Resolution NMR Spectroscopy
  • Author : Rubén H. Contreras,M.B. Ferraro,Martin C. Ruiz de Azúa,Gustavo A. Aucar
  • Publisher : Elsevier Inc. Chapters
  • Release : 08 June 2013
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This chapter describes briefly chemical shifts (or nuclear magnetic shielding constants) and indirect spin–spin coupling constants. They are well known as powerful tools for studying several molecular properties which are very important in different branches of the broad field of molecular sciences. The present description is oriented to an interdisciplinary audience and therefore it is expected that it can be followed for readers without strong backgrounds either in mathematics or physics. After a short revision of basic concepts, a

High Resolution NMR Spectroscopy

High Resolution NMR Spectroscopy
  • Author : Rubén H. Contreras
  • Publisher : Elsevier Inc. Chapters
  • Release : 08 June 2013
GET THIS BOOKHigh Resolution NMR Spectroscopy

In this introductory chapter are described briefly the aims and scopes of this multiauthor book. One of the main ideas behind them is helping its readership to understand some approaches for extracting information on subtle chemical interactions, defining trends of such parameters from either measured or calculated high-resolution NMR parameters (indirect nuclear spin–spin coupling constants and nuclear magnetic shielding constant) without needing to acquire solid backgrounds on quantum chemistry. However, in all cases, the discussed ideas are based on

High Resolution NMR Spectroscopy

High Resolution NMR Spectroscopy
  • Author : Rubén H. Contreras,Cláudio F. Tormena,Lucas C. Ducati,T. Llorente
  • Publisher : Elsevier Inc. Chapters
  • Release : 08 June 2013
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In this chapter, the qualitative model described in is applied to show systematic rationalizations in terms of chemical interactions that define well-known trends for chemical shifts corresponding to 13C, 15N, 17O, and 19F isotopes. The theoretical fundamentals for this approach are given in . They could be a bit difficult to follow for readers who do not have a good training in physics and mathematics. However, this difficulty was intended to be overcome by resorting in to describing this approach and

High Resolution NMR Spectroscopy

High Resolution NMR Spectroscopy
  • Author : Krystyna Kamieńska-Trela,Jacek Wójcik
  • Publisher : Elsevier Inc. Chapters
  • Release : 08 June 2013
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This chapter is devoted to the 1–3JCCs and to the factors influencing their magnitude. The experimental and calculated J data presented in the subsequent parts of the chapter are arranged with the thought of showing how hybridization, substituent electronegativity, the complex and hydrogen bond formation, and geometry of the compound bear on the JCC magnitude and which range of changes can be expected for a given type of coupling when all these effects are taken into account. The subsequent sections

High Resolution NMR Spectroscopy

High Resolution NMR Spectroscopy
  • Author : Juha Vaara
  • Publisher : Elsevier Inc. Chapters
  • Release : 08 June 2013
GET THIS BOOKHigh Resolution NMR Spectroscopy

The theory and quantum-chemical calculations of the spectral parameters of nuclear magnetic resonance (NMR) are well established in the case of diamagnetic, closed-shell molecules. In contrast, NMR calculations of paramagnetic, open-shell molecules (pNMR) are scarce, limited by both assumptions within the underlying theoretical background as well as the availability of computational implementations. We discuss the systematic development of pNMR theory that recently culminated in a novel, general and systematic electronic structure approach for the shielding tensor and the associated chemical

High Resolution NMR Spectroscopy

High Resolution NMR Spectroscopy
  • Author : J.M. García de la Vega,J. San Fabián
  • Publisher : Elsevier Inc. Chapters
  • Release : 08 June 2013
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Natural bond orbital and natural J-coupling methods are used for the analysis of the Fermi-contact contributions to spin–spin coupling constant (SSCC). In this way, the SSCCs are partitioned into three contributions: Lewis, delocalization, and repolarization. This partition is applied to the study of some chemical systems to explain the main electron delocalization effects on SSCCs.

High Resolution NMR Spectroscopy

High Resolution NMR Spectroscopy
  • Author : Rubén H. Contreras,Cláudio F. Tormena,Lucas C. Ducati
  • Publisher : Elsevier Inc. Chapters
  • Release : 08 June 2013
GET THIS BOOKHigh Resolution NMR Spectroscopy

In this chapter, several nJXY SSCC trends involving the X and Y light atoms are discussed with considerable detail for different values of n, the number of formal bonds separating both coupling nuclei. First, couplings contributed mainly by the FC interaction are considered. Insight into their transmission mechanisms is obtained using at least one of the following three approaches: (a) the qualitative model described in ; (b) the FCCP-CMO approach, that is, studying Fermi contact coupling pathways in terms of canonical

High Resolution NMR Spectroscopy

High Resolution NMR Spectroscopy
  • Author : P. Lazzeretti
  • Publisher : Elsevier Inc. Chapters
  • Release : 08 June 2013
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The Ramsey theory of nuclear magnetic resonance spectral parameters has been reformulated in terms of current densities induced in the electron cloud of a molecule by an external magnetic field and intramolecular magnetic dipoles at the nuclei. Conditions for invariance of nuclear magnetic shielding and nuclear spin–spin coupling tensors, in gauge transformations of the vector potentials associated to the magnetic perturbations, have been expressed via quantum mechanical sum rules, also providing constraints for charge conservation. It is shown that

High Resolution NMR Spectroscopy

High Resolution NMR Spectroscopy
  • Author : Jochen Autschbach
  • Publisher : Elsevier Inc. Chapters
  • Release : 08 June 2013
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For heavy atoms, and for molecules with heavy atoms, a theoretical description of the electronic structure needs to consider the finite speed of light and Einstein’s special relativity. This chapter provides a brief introduction to special relativity and to relativistic methods in quantum chemistry. It is shown how these methods can be used to calculate NMR chemical shifts and indirect spin–spin coupling constants (J-coupling). A number of examples are discussed where relativistic effects have a significant influence on