Semiempirical Molecular Orbital Research Articles

ChemInform Abstract: SEMIEMPIRICAL MOLECULAR ORBITAL CONSIDERATIONS OF THE ELECTRONIC STRUCTURES OF TRANSITION METAL COMPLEXES. I. DIOXYGEN NICKEL COMPLEXES

Chemischer InformationsdienstVolume 7, Issue 48 Physical Organic Chemistry ChemInform Abstract: SEMIEMPIRICAL MOLECULAR ORBITAL CONSIDERATIONS OF THE ELECTRONIC STRUCTURES OF TRANSITION METAL COMPLEXES. I. DIOXYGEN NICKEL COMPLEXES K. TATSUMI, K. TATSUMISearch for more papers by this authorT. FUENO, T. FUENOSearch for more papers by this authorA. NAKAMURA, A. NAKAMURASearch for more papers by this authorS. OTSUKA, S. OTSUKASearch for more papers by this author K. TATSUMI, K. TATSUMISearch for more papers by this authorT. FUENO, T. FUENOSearch for more papers by this authorA. NAKAMURA, A. NAKAMURASearch for more papers by this authorS. OTSUKA, S. OTSUKASearch for more papers by this author First published: November 30, 1976 https://doi.org/10.1002/chin.197648062Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume7, Issue48November 30, 1976 RelatedInformation

ChemInform Abstract: ELECTRONIC STRUCTURE AND SPECTRA OF ORGANIC MOLECULES PART 19, SEMIEMPIRICAL MOLECULAR ORBITAL CALCULATIONS FOR PYRIDINEALDOXIMES AND ACETAMIDOPYRIDINES

Chemischer InformationsdienstVolume 6, Issue 31 Physical Organic Chemistry ChemInform Abstract: ELECTRONIC STRUCTURE AND SPECTRA OF ORGANIC MOLECULES PART 19, SEMIEMPIRICAL MOLECULAR ORBITAL CALCULATIONS FOR PYRIDINEALDOXIMES AND ACETAMIDOPYRIDINES J. S. KWIATKOWSKI, J. S. KWIATKOWSKISearch for more papers by this authorW. HERZOG, W. HERZOGSearch for more papers by this authorB. SZCZODROWSKA, B. SZCZODROWSKASearch for more papers by this author J. S. KWIATKOWSKI, J. S. KWIATKOWSKISearch for more papers by this authorW. HERZOG, W. HERZOGSearch for more papers by this authorB. SZCZODROWSKA, B. SZCZODROWSKASearch for more papers by this author First published: August 5, 1975 https://doi.org/10.1002/chin.197531077AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume6, Issue31August 5, 1975 RelatedInformation

Point defects in hexagonal boron nitride. II. Theoretical studies

Substitutional and displaced carbon impurities and an isolated nitrogen vacancy in hexagonal boron nitride are theoretically investigated by the "small periodic cluster" approach. The perfect-solid band structure is calculated from the solution of the eigenvalues of a finite and periodic cluster of atoms arranged according to the known crystal structure. The linear combination of atomic orbitals representation of the crystal orbitals is adopted and semiempirical MO (molecular orbital) methods (extended Huckel, iterative extended Huckel) are used for the solution of the electronic eigenvalue problem. Point-defect problems are then treated by introducing the impurity atom or the vacant site into the otherwise perfect periodic cluster, and repeating the solution. Lattice relaxations are introduced around the defect site and charge redistribution among the cluster atoms is allowed for via self-consistent MO treatment. For a substitutional carbon impurity defect, it is observed that two deep defect levels, mainly localized on the carbon atom, appear (3.2-4.9 eV below the conduction band). Another level splits from the conduction band as the carbon atom is raised from the layer plane in a perpendicular direction. This level, 1.0-1.3 eV below the conduction band, has a symmetrical charge distribution on the three boron atoms surrounding the impurity site. As the distance of the carbon atom from the layer plane is increased to infinity, a nitrogen vacancy is formed. It is characterized by a defect level 1.1-1.4 eV apart from the conduction-band edge which also possesses a three-boron character. Lattice relaxations were shown to stabilize these defects. The findings agree semiquantitatively with the experimental results on these defects.

Effect of lone-pair orientation on nuclear spin couplings

The 2 J nh and 1 J ch couplings involving 15N and 13C in oximes have been studied theoretically by the finite perturbation method employing CNDO/2 and INDO wave functions. The couplings are found to be significantly influenced by the orientation of the nitrogen lone-pair orbital. It has been shown that the dihedral-angle dependence of vicinal H-H coupling in methylamine is also influenced by the orientation of the lone-pair on nitrogen, leading to deviations in the couplings predicted by a Karplus-type equation. The localized molecular orbitals and the hybridization and orientation of the nitrogen lone-pair in these molecules have been obtained by the Edmiston-Ruedenberg transformation of the semi-empirical SCF molecular orbitals.

Optical Spectra of Divalent Manganese Salts. I. Energy Levels for Cubic and Lower-Symmetry Complexes

An extensive study of the optical absorption spectra of Mn(II) salts is introduced with a re-examination of the nature of crystal-field independent transitions and their dependence upon slight changes in ligand positions. Evidence for an unexpected but significant decrease in metal—ligand bond lengths for the 4A2 state with respect to those for 6A1 equilibrium ground state is obtained both from experiment, in terms of the excitation of totally symmetric displacements, and from approximate calculations. The latter involve both an extended formulation of the nephelauxetic effect and molecular orbital (MO) parameters obtained by a semiempirical LCAO MO scheme. A classification scheme for crystal-field independent transitions, not necessarily in Mn(II) complexes, is introduced, and is based on the type of molecular orbitals, σ, π, or both, appearing in the exchange integrals associated with the transition energies. Low-symmetry effects, especially for the 4E states, are discussed.

Electronic States of Para-Benzoquinone. II. Calculation of the Energy Levels by a Semiempirical Molecular Orbital Method Including Configuration Interaction

Electronic States of <i>Para</i>-Benzoquinone. II. Calculation of the Energy Levels by a Semiempirical Molecular Orbital Method Including Configuration Interaction