Structures and intriguing conformational behavior of 1- and 2-naphthalenesulfonamides as determined by gas-phase electron diffraction and computational methods.
J Phys Chem A
; 119(9): 1502-10, 2015 Mar 05.
Article
de En
| MEDLINE
| ID: mdl-25222639
ABSTRACT
The saturated vapors of 1- and 2-naphthalenesulfonamides (1-NaphSA and 2-NaphSA) were studied by the gas-phase electron diffraction/mass-spectrometric method at 413(9) and 431(9) K. According to quantum chemical calculations (DFT/B3LYP and MP2 with cc-pVDZ, aug-cc-pVDZ, cc-pVTZ, and aug-cc-pVTZ basis set) 1-NaphSA possesses four conformers with different orientations of the SO2NH2 fragment relative to the naphthalene frame and eclipsed or staggered orientation of the N-H and SâO bonds, whereas 2-NaphSA possesses only two conformers with different orientations of the N-H and SâO bonds. It was experimentally established that vapors over 1-NaphSA and 2-NaphSA exist predominantly (up to 75 mol %) of low-energy conformers of C1 symmetry in which the C-S-N planes deviate from perpendicular orientation relative to the naphthalene skeleton with near eclipsed orientation of the N-H and SâO bonds of the SO2NH2 fragment. The following geometrical parameters (Å and degrees) of the dominant conformers were derived r(h1)(C-H) = 1.089(4), r(h1)(C-C)av = 1.411(3), r(h1)(C-S) = 1.761(10), r(h1)(S-O)av = 1.425(3), r(h1)(S-N) = 1.666(10), â C-C1-C = 119.8(2), â C1-S-N = 104.5(22), C9-C1-S-N = 69.5(30) for 1-NaphSA; r(h1)(C-H) = 1.083(5), r(h1)(C-C)av = 1.411(3), r(h1)(C-S) = 1.780(7), r(h1)(S-O)av = 1.427(4), r(h1)(S-N) = 1.668(6), â C-C2-C = 123.0(3), â C2-S-N = 103.6(19), C1-C2-S-N = 110(10) for 2-NaphSA. The connection between nonequivalence of the C-C bonds in the naphthalene frame and spatial orientation of the substituents SO2NH2 is discussed. Transition states between conformers and enantiomers were determined.
Texte intégral:
1
Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
Théorie quantique
/
Sulfonamides
/
Électrons
/
Naphtalènes
Langue:
En
Journal:
J Phys Chem A
Sujet du journal:
QUIMICA
Année:
2015
Type de document:
Article
Pays d'affiliation:
Russie