Sulfonyl radicals, sulfinic acid, and related species: an abinitio molecular orbital study

1980 ◽  
Vol 58 (4) ◽  
pp. 331-338 ◽  
Author(s):  
Russell J. Boyd ◽  
Abha Gupta ◽  
Richard F. Langler ◽  
Stephen P. Lownie ◽  
James A. Pincock
Keyword(s):  
Molecular Orbital ◽  
Functional Group ◽  
Basis Set ◽  
Geometrical Parameters ◽  
Molecular Orbital Calculations ◽  
Sulfinic Acid ◽  
Molecular Orbital Study ◽  
Polarization Functions ◽  
Total Energies ◽  
D Orbitals

Extensive abinitio molecular orbital calculations on six sulfonyl radicals (XSO2 where X = H, CH3, NH2, OH, F, and Cl), the simplest sulfinic acid HSO2H3 and its isomeric sulfone H2SO2, the HSO2− anion of sulfinic acid, the isomeric anion SO2H−, and for completeness, the SO2H radical are presented. By use of the STO-3G* basis set, which includes d-type polarization functions on second-row atoms, all geometrical parameters are varied until the total energy is minimized, subject only to certain symmetry restrictions specified for each system. The inclusion of d orbitals on S is observed to affect the S—O bond lengths by as much as 0.45 Å. The calculations suggest that the radical site in sulfonyl radicals is significantly delocalized over the entire functional group and that the geometrical parameters of the SO2 functional group in sulfonyl radicals are nearly independent of the substituent (r(S—O) = 1.47 ± 0.01 Å, < OSO = 123 ± 2°). Estimates of the X—S bond energy in CH3SO2, NH2SO2, and OHSO2 are consistent with the chemistry of alkylsulfonyl and aminosulfonyl radicals and lead to an interesting prediction for alkoxylsulfonyl radicals. Furthermore the calculations yield lower total energies for HSO2H, HSO2−, and SO2H than for the respective isomeric forms H2SO2, SO2H−, and HSO2.

Abinitio molecular orbital calculations for SF4, SOF2, and SO2F2

1981 ◽  
Vol 59 (5) ◽  
pp. 814-816 ◽  
Author(s):  
N. Colin Baird ◽  
Kathleen F. Taylor
Keyword(s):  
Molecular Orbital ◽  
Sulfur Atom ◽  
Basis Set ◽  
Molecular Orbital Calculations ◽  
Constant Amount ◽  
Bond Lengths ◽  
Equilibrium Structures ◽  
Gaussian Orbitals ◽  
D Orbitals ◽  
Extended Basis

Abinitio molecular orbital calculations are reported for SF4 (both C2v and C4v symmetries), SOF2, and SO2F2. Geometry searches were conducted using the STO-3G* basis set; the energies were recalculated at the predicted equilibrium structures also using STO-3G and 44-31G, and the latter basis set with the addition of five real d Gaussian orbitals on the sulfur atom. The predicted geometries agree well with experiment, although S=O bonds are consistently predicted too long by ∼0.03 Å, and the variation in S—F bond lengths among different environments is underestimated. The energy stabilization associated with the addition of d orbitals is generally consistent with our previous calculations, i.e. it is a constant amount per bond in hypervalent sulfur compounds in extended basis calculations. Replacement of F by OH is predicted to be more exothermic in SO2F2 than in SOF2, and the relevance of this prediction to estimated heats of formation for SOF2 and SO(OH)2 is discussed.

Importance of Orbital Complementarity in Spin Coupling through Two Different Bridging Groups in Dicopper(II) Complexes of Endogenous Alkoxo Bridging Ligand with Exogenous Carboxylate: Ab-initio and Semi-Empirical Calculations

2007 ◽  
Vol 62 (7-8) ◽  
pp. 409-416 ◽  
Author(s):  
C. Tugrul Zeyrek
Keyword(s):  
Ab Initio ◽  
Molecular Orbital ◽  
Magnetic Behaviour ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Energy Separation ◽  
Molecular Orbital Calculations ◽  
Bridging Ligand ◽  
Spin Singlet ◽  
D Orbitals

The influence of overlap interactions between the bridging ligands and the metal d orbitals on the super-exchange coupling constant are studied by means of ab-initio restricted Hartree-Fock molecular orbital calculations. The interaction between the magnetic d orbitals and the HOMOs of the carboxylate oxygen atoms are investigated in homologous asymmetrically dibridged dicopper(II) complexes which have significantly different - 2J values (the energy separation between the spin-triplet and spin-singlet states). In order to determine the nature of the fronter orbitals, extended Hückel molecular orbital (EHMO) calculations are also reported. The differences in the magnitude of the coupling constants and magnetic behaviour are rationalized in terms of the bridging ligand orbital complementary / countercomplementary concept.

Theoretical Molecular Orbital Study on the Role of Transition-Metal d Orbitals in Chemisorption of Acetylene

1983 ◽  
Vol 87 (7) ◽  
pp. 1140-1145 ◽  
Author(s):  
Hisayoshi Kobayashi ◽  
Satohiro Yoshida ◽  
Masaru Yamaguchi
Keyword(s):  
Transition Metal ◽  
Molecular Orbital ◽  
Molecular Orbital Study ◽  
Orbital Study ◽  
D Orbitals

The electronic structure of the tetrasulphur tetranitride dication, S4N42+: an abinitio molecular orbital study

1982 ◽  
Vol 60 (17) ◽  
pp. 2281-2285 ◽  
Author(s):  
Milan Trsic ◽  
William G. Laidlaw ◽  
Richard T. Oakley
Keyword(s):  
Electronic Structure ◽  
Molecular Orbital ◽  
Bond Order ◽  
Electron System ◽  
Molecular Orbital Calculations ◽  
Hartree Fock ◽  
Molecular Orbital Study ◽  
Orbital Study ◽  
Uv Visible

Abinitio Hartree–Fock–Slater molecular orbital calculations on the planar tetrasulphur tetranitride dication S4N42+ reveal that it can be described as a fully delocalised 10 π-electron system. Overlap populations for the NS bonds suggest a bond order substantially stronger than in neutral S4N4. The strong uv/visible absorptions observed for S4N42+ at 346 and 262 nm are assigned to nπS → π* and nπN → π* excitations. The Hartree–Fock–Slater π-molecular orbital manifold is discussed in relation to simple HMO concepts.

Protonation Effect on C-N Bond Length of Alkylamines Studied by Molecular Orbital Calculations

2000 ◽  
Vol 55 (9-10) ◽  
pp. 769-771 ◽  
Keyword(s):  
Density Functional Theory ◽  
Bond Length ◽  
Molecular Orbital ◽  
Density Functional ◽  
Second Order ◽  
Basis Set ◽  
Molecular Orbital Calculations ◽  
Functional Theory ◽  
Hartree Fock ◽  
Protonation Effect

Abstract Molecular orbital calculations were performed for the six saturated alkylamines (CH3NH2 , (CH3)2 NH, (CH 3)3 N, CH 3CH2NH2 , (CH3)2 CHNH2 , (CH3)3 CNH2), their protonated cations (CH3NH3 + , (CH3)2NH2 + , (CH3)3NH + , CH3CH2NH3 + , (CH3)2CHNH3 + , (CH3)3CNH3+), and (CH3)4 N + using the Hartree-Fock, second-order M0ller-Plesset, and density functional theory methods with the 6-311+G(d,p) basis set. Protonation lengthens the C-N bonds of the amines by 0.05 -0.08 Å and shortens the C-C bonds of CH3CH2NH2, (CH3)2CHNH2 , and (CH3)3CNH2 by ca. 0.01 Å.

Structures of simple anions from ab initio molecular orbital calculations

1976 ◽  
Vol 29 (8) ◽  
pp. 1635 ◽  
Author(s):  
L Radom
Keyword(s):  
Ab Initio ◽  
Molecular Orbital ◽  
Basis Set ◽  
Basis Sets ◽  
Molecular Orbital Calculations ◽  
Limited Information ◽  
Orbital Theory ◽  
Comparable Quality ◽  
Split Valence ◽  
Theoretical Results

Ab initio molecular orbital theory with the minimal STO-3G and split-valence 4-31G basis sets is used to obtain geometries of 18 anions:OH-, NH2-, HF2-, BH4-, BF4-, C22-, CN-, NCN2-, N3-, NO2-, NO3-, 0CCO2-, CO32-, HCOO-, CH3COO-, C2O42-, C4O42- and C(CN)3-. The theoretical results are compared with experimental results from the literature. The STO-3G basis set performs somewhat worse for anions than for neutral molecules. On the other hand, the 4-31G basis set gives good results and predicts bond lengths to within 0.02� for all the molecules considered. Limited information on bond angle predictions suggests that these are of comparable quality to those for neutral molecules. The tricyanomethanide ion is predicted to be planar.

Ab initio molecular orbital study of the effects of basis set size on the calculated structure and acidity of hydroxyl groups in framework molecular sieves

1992 ◽  
Vol 96 (25) ◽  
pp. 10247-10257 ◽  
Author(s):  
John B. Nicholas ◽  
Randall E. Winans ◽  
Robert J. Harrison ◽  
Lennox E. Iton ◽  
Larry A. Curtiss ◽  
...  
Keyword(s):  
Ab Initio ◽  
Molecular Orbital ◽  
Molecular Sieves ◽  
Basis Set ◽  
Hydroxyl Groups ◽  
Set Size ◽  
Molecular Orbital Study ◽  
Orbital Study

Ab initio molecular orbital study of simple 1,3-dipolar reactions

1976 ◽  
Vol 29 (3) ◽  
pp. 465 ◽  
Author(s):  
D Poppinger
Keyword(s):  
Transition State ◽  
Ab Initio ◽  
Molecular Orbital ◽  
Transition States ◽  
Basis Sets ◽  
Molecular Orbital Calculations ◽  
Molecular Orbital Study ◽  
Orbital Study ◽  
Extended Basis ◽  
Optimized Geometries

Ab initio molecular orbital calculations with minimal and extended basis sets have been carried out for the 1,3-dipolar addition of fulminic acid to acetylene, ethylene, ethynamine and propynenitrile. Optimized geometries are reported for the transition states HCNO+C2H2, HCNO+C2H4, HCNO+ C2HNH2, for the adducts isoxazole and 2-isoxazoline, and for nitrosocyclopropene as a possible intermediate. The calculations indicate that (a) these 1,3-dipolar reactions are synchronous processes, (b) the geometry of the transition state is insensitive to substitution and (c) of the isomeric substituted adducts, 5-aminoisoxazole and isoxazole-4-carbonitrile should be formed preferentially.

Substitutent Effects on the Geometrical Properties of 1-Phenylallyl Alcohol

2005 ◽  
Vol 60 (4) ◽  
pp. 265-270
Author(s):  
Salim Y. Hanna ◽  
Salim M. Khalil ◽  
Moafaq Y. Shandala
Keyword(s):  
Electron Density ◽  
Molecular Orbital ◽  
Substituent Effects ◽  
Heats Of Formation ◽  
Geometrical Parameters ◽  
Molecular Orbital Calculations ◽  
Electron Densities ◽  
Geometrical Properties ◽  
Stabilization Energies

Abstract Optimized geometrical parameters, electron densities, heats of formation and stabilization energies have been obtained on X-substituted phenylallyl alcohols, where X is H, OCH3, NH2, CN, F and CH3 at ortho, meta, and para positions, using MINDO-Forces SCF-molecular orbital calculations. The substituent effects on the geometrical parameters and the electron density are discussed.

Molecular Orbital Calculations of Cu-Halides

1981 ◽  
Vol 36 (10) ◽  
pp. 1095-1099 ◽  
Author(s):  
H. Itoh
Keyword(s):  
Ab Initio ◽  
Molecular Orbital ◽  
Energy Levels ◽  
Basis Set ◽  
Orbital Energy ◽  
Ionic Character ◽  
Molecular Orbital Calculations ◽  
Ab Initio Hf ◽  
Mo Theory

An ab initio HF MO theory is applied to CuX, CuX2 (X = F and Cl) and (CuCl)3 . Although the detailed sequence of energy levels depends upon the basis set used, high-lying orbital energy levels have largely halogen p-like character, whereas low-lying orbital energy levels have largely Cu 3 d-like character. This is in agreement with the chemical intuition of a highly ionic character of these compounds.

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