The structure of a thiadiazole-containing expanded heteroazaporphyrinoid determined by gas electron diffraction and density functional theory calculations

2008 ◽  
pp. 3573 ◽  
Author(s):  
Alexander V. Zakharov ◽  
Sergey A. Shlykov ◽  
Natalia V. Bumbina ◽  
Elena A. Danilova ◽  
Alexander V. Krasnov ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Electron Diffraction ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Gas Electron Diffraction ◽  
Functional Theory

The Molecular Structures and Conformational Preferences of Bis(dimethylstibyl)- Oxane, -Sulfane and -Selane, E(SbMe2)2, E = O, S or Se, Me = CH3, by Density Functional Theory Calculations and Gas Electron Diffraction

1997 ◽  
Vol 52 (2) ◽  
pp. 296-300 ◽  
Author(s):  
Arne Haaland ◽  
Vasili Ivanovitch Sokolov ◽  
Hans Vidar Volden ◽  
Hans Joachim Breunig ◽  
Michael Denker ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Electron Diffraction ◽  
Density Functional ◽  
Lone Pair ◽  
Density Functional Theory Calculations ◽  
Molecular Structures ◽  
Gas Electron Diffraction ◽  
Electron Diffraction Data ◽  
Functional Theory ◽  
Anti Conformer

Abstract Density Functional Theory calculations on E(SbMe2)2, E = O, S or Se, Me = CH3, indicate that the equilibrium structures are syn-syn or near syn-syn conformers with over-all C2 symmetry. The barriers restricting rotation about E-Sb bonds are very low, the equilibrium values for the dihedral angles ϕ(Sb-E-Sb-lp) where lp denotes the direction of the electron lone pair on one of the Sb atoms are probably less than 45°. The calculations further indicate the existence of syn-anti conformers some 4 kJ mol-1 above the more stable syn-syn. Gas electron diffraction data show that both conformers are present in gaseous O(SbMe2)2, while the presence of the syn-anti conformer in gaseous Se(SbMe2)2 is uncertain; least-squares refinements yielded the mole fraction χ = 0.27(18). The Sb-O and Sb-Se bond distances are 197.6(14) and 255.1(5) pm respectively, the valence angles of the syn-syn conformers are <SbOSb = 122.3(16)° and <SbSeSb = 96.3(11)°. It is suggested that the wide <SbOSb angle is due to across-angle repulsion between the Sb atoms.

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