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Titolo:
Oxygen-by-sulfur substitutions in glycine: conformational and vibrational effects
Autore:
de Carvalho, LAEB; Marques, MPM; Teixeira-Dias, JJC;
Indirizzi:
Univ Coimbra, Fac Ciencias & Tecnol, Unidade I&D Quim Fis Mol, P-3049 Coimbra, Portugal Univ Coimbra Coimbra Portugal P-3049 m Fis Mol, P-3049 Coimbra, Portugal Univ Coimbra, Fac Ciencias & Tecnol, Dept Bioquim, P-3049 Coimbra, Portugal Univ Coimbra Coimbra Portugal P-3049 t Bioquim, P-3049 Coimbra, Portugal Univ Aveiro, Dept Quim, P-3810 Aveiro, Portugal Univ Aveiro Aveiro Portugal P-3810 o, Dept Quim, P-3810 Aveiro, Portugal
Titolo Testata:
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2
fascicolo: 11, , anno: 1999,
pagine: 2507 - 2514
SICI:
0300-9580(199911):11<2507:OSIGCA>2.0.ZU;2-P
Fonte:
ISI
Lingua:
ENG
Soggetto:
MOLECULAR-ORBITAL METHODS; MILLIMETER WAVE SPECTRUM; VALENCE BASIS-SETS; 2ND-ROW ELEMENTS; POTENTIAL-ENERGY; GASEOUS GLYCINE; NEUTRAL FORMS; HARTREE-FOCK; GAS-PHASE; CONFORMERS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
41
Recensione:
Indirizzi per estratti:
Indirizzo: de Carvalho, LAEB Univ Coimbra, Fac Ciencias & Tecnol, Unidade I&D Quim Fis Mol, P-3049 Coimbra, Portugal Univ Coimbra Coimbra Portugal P-3049 Coimbra, Portugal
Citazione:
L.A.E.B. de Carvalho et al., "Oxygen-by-sulfur substitutions in glycine: conformational and vibrational effects", J CHEM S P2, (11), 1999, pp. 2507-2514

Abstract

Molecular geometries, energies, dipole moments and atomic charges of several conformations of glycine (NH2CH2C(=O)OH) and its oxygen-by-sulfur substituted analogues (NH2CH2C(=O)SH, NH2CH2C(=S)OH and NH2CH2C(=S)SH) were determined by ab initio MO calculations at the MP2/6-31G** level, and vibrational frequencies, infrared and Raman intensities were evaluated within the harmonic approximation, dt the HF/6-31G** level. Profiles for the potential energy and several geometric parameters as a function of the NC-C(=X) (X = O,S) dihedral angle (C-C internal rotation) were obtained using the 3-21G(N*) basis set. Conformational and vibrational effects of oxygen-by-sulfur substitutions are discussed. In particular, the occurrence of intramolecular close contacts between the NH2CH2- and -C(=X)YH (X, Y = O or S) moieties of the molecule is considered, for some of the most stable conformations of each analogue. As a general trend, the results dearly point to the stabilisation of the G/anti forms (:NCC congruent to 60 degrees, NCCX congruent to 180 degrees), highlighting the importance of the N:... H(Y) and N:... S(H) interactions, e.g. in conformers G/antils-trans for the thione form (X = S) and G/anti/s-cis for the thiol one (Y = S), respectively.

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Documento generato il 12/07/20 alle ore 02:19:20