Solid-state 17O NMR studies of organic and biological molecules

Chemical shifts calculations on aromatic systems: a comparison of models and basis sets

Efficient scheme for construction of physically justified STO##-3Gel and STO##-3Gmag basis sets has been proposed. It is based upon the analysis of analytical form of the first-order correction functions to unperturbed STO basis sets under the perturbation by electric or magnetic fields. The test calculations of polarizability, magnetic susceptibility and chemical shifts performed for a series of aromatic compounds within the developed basis set in the framework of Hartree-Fock and Density Functional Theory (DFT) approaches show good agreement of the predicted properties with experiments. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011

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Novel physically adapted STO##‐3G basis sets. Efficiency for prediction of second‐order electric and magnetic properties of aromatic hydrocarbons

The present study examines the quality of the restricted HartreeFock (RHF) ab initio, B3LYP hybrid density functional theory (DFT), and relativistic zeroth-order regular approximation (ZORA) DFT methods for the calculation of phosphorus chemical shift (CS) tensors in phosphine, phosphido, and phosphinidene transition-metal complexes. A detailed comparison of calculated and experimental 31P CS tensors allows us to identify the characteristic advantages of each computational method. The results from B3LYP and ZORA-DFT calculations indicate that a double-ζ quality basis set reproduces experimental values of the principal components of the 31P CS tensor in many of the phosphorus-containing transition-metal complexes investigated, whereas the RHF method requires a triple-ζ doubly polarized basis set, yet fails in the case of the terminal phosphido group. Inclusion of the spin-orbit relativistic correction with the ZORA-DFT formalism requires a triple-ζ quality basis set to reproduce the experimental data. We ...

Phosphorus magnetic shielding tensors for transition-metal compounds containing phosphine, phosphido, and phosphinidene ligands: Insights from computational chemistry

A survey of the chemical literature published within 1995–2005 dealing with the chemical reactivity and synthesis of acyclic oxiranes (epoxides) and oxirenes is presented. The reactivity of acyclic epoxides is discussed first, specifically including sections on thermal or photochemical reactions, the use of epoxides as electrophiles for nucleophilic ring-opening reactions, radical reactions, isomerizations promoted by basic or acidic conditions, reductions, deoxygenations, cycloadditions, metal-catalyzed reactions, and polymerizations. The synthesis of oxiranes between 1995 and 2005 is split into two subsections, nonenantioselective and enantioselective methods. Within each subsection, examples describing intramolecular substitution, epoxidation of alkenes using peracids, dioxiranes, molecular oxygen, hydrogen peroxide, oxaaziridines, metal and biological catalysis are presented. Short sections dealing with recent chemistry of allene oxides and oxirenes are also presented.

Oxiranes and Oxirenes: Monocyclic

The results of theoretical and experimental investigation of 17O NMR chemical shifts for a number of epoxidic compounds are reported. The calculations were performed for the MP2/6-311G(d) level reference geometries using the GIAO and CSGT methods within the coupled Hartree−Fock perturbation theory. Various basis sets were applied in calculations of the chemical shifts. The performance of recently developed magnetically consistent basis sets and their advantages over the standard ones are discussed. The obtained results allow one to assign NMR signals for epoxides for which experimental data were obtained for the mixtures of stereoisomers.

Sergey I. Okovytyy

Papers

An Investigation of the 17O NMR Chemical Shifts in Oxiranes Using Magnetically Corrected Basis Sets