Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
Evidence of C-H center dot center dot center dot O hydrogen bonds in liquid 4-ethoxybenzaldehyde by NMR and vibrational spectroscopies
Autore:
Marques, MPM; da Costa, AMA; Ribeiro-Claro, PJA;
Indirizzi:
Univ Coimbra, Unidade Quim Fis Mol, Fac Ciencias & Tecnol, P-3004353 Coimbra, Portugal Univ Coimbra Coimbra Portugal P-3004353 nol, P-3004353 Coimbra, Portugal Univ Aveiro, Dept Quim, P-3810193 Aveiro, Portugal Univ Aveiro Aveiro Portugal P-3810193 t Quim, P-3810193 Aveiro, Portugal
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY A
fascicolo: 21, volume: 105, anno: 2001,
pagine: 5292 - 5297
SICI:
1089-5639(20010531)105:21<5292:EOCCDC>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
AB-INITIO CALCULATIONS; INTRAMOLECULAR INTERACTIONS; FORMIC-ACID; DIMERS; COMPLEX; 4-METHOXYBENZALDEHYDE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
41
Recensione:
Indirizzi per estratti:
Indirizzo: Ribeiro-Claro, PJA Univ Coimbra, Unidade Quim Fis Mol, Fac Ciencias & Tecnol, P-3004353 Coimbra, Portugal Univ Coimbra Coimbra Portugal P-3004353 bra, Portugal
Citazione:
M.P.M. Marques et al., "Evidence of C-H center dot center dot center dot O hydrogen bonds in liquid 4-ethoxybenzaldehyde by NMR and vibrational spectroscopies", J PHYS CH A, 105(21), 2001, pp. 5292-5297

Abstract

Raman, FTIR, and NMR (both C-13 and O-17) spectroscopies are used in a complementary way in order to study the occurrence of C-H . . .O intermolecular hydrogen bonds in liquid 4-ethoxybenzaldehyde (4EtOB), Additional information concerning the structure of the possible dimers is obtained through abinitio calculations, at the B3LYP/6-31G* level. The strongest evidences ofthe presence of C-H . . .O hydrogen bonds in the liquid phase arise from the temperature and solvent intensity dependence of the two bands observed in the nu (C=O) region of the vibrational spectra, as well as from the shiftto low magnetic field detected for the carbonyl O-17 NMR peak at higher dilutions. Further evidence is gathered from the changes observed in the nu (C-H) vibrational modes, the (1)J(CH) concentration dependence detected in the NMR spectra, and ab initio results. The experimental observations are consistent with the decrease of the C-H bond length upon hydrogen-bonding, aspredicted for the nonstandard blue-shifting hydrogen bonds. Ab initio calculations predict several possible structures for the dimeric species, with nearly identical energies. The calculated dimerization energy is within the-5.1 to -6.5 kJ mol(-1) range, considering both basis set superposition error and zero-point vibrational energy corrections, in agreement with the obtained experimental DeltaH value of -5.7 +/- 0.5 kJ mol(-1).

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 16/07/20 alle ore 06:44:19