Please use this identifier to cite or link to this item:
https://hdl.handle.net/10316/17920
DC Field | Value | Language |
---|---|---|
dc.contributor.author | Breda, S. | - |
dc.contributor.author | Reva, I. | - |
dc.contributor.author | Lapinski, L. | - |
dc.contributor.author | Fausto, R. | - |
dc.date.accessioned | 2011-12-14T16:13:12Z | - |
dc.date.available | 2011-12-14T16:13:12Z | - |
dc.date.issued | 2006-08-31 | - |
dc.identifier.uri | https://hdl.handle.net/10316/17920 | - |
dc.description.sponsorship | Squaric acid dimethyl ester (C6O4H6; 3,4-dimethoxycyclobut-3-ene-1,2-dione; DCD) was studied by matrix isolation infrared spectroscopy and by density functional theory (B3LYP) and ab initio (MP2) calculations with the 6-31++G(d,p) and 6-311++G(d,p) basis sets. Three conformers of the compound were theoretically predicted. The two most stable conformers were identified in low-temperature argon matrixes and the energy gap between them was determined. The trans−trans conformer (C2v) was found to be more stable than the cis−trans form (Cs) by 4.2 kJ mol-1, in consonance with the theoretical predictions (MP2 calcd = 3.9 kJ mol-1). In situ broadband UV irradiation (λ > 337 nm) of the matrix-isolated compound was found to induce the ring-opening reaction leading to production of the bisketene, 2,3-dimethoxybuta-1,3-diene-1,4-dione as well as the trans−trans → cis−trans conformational isomerization. The latter phototransformation allowed separation of the infrared spectra of the two conformers initially trapped into a low-temperature matrix. Upon higher energy irradiation (λ > 235 nm), the main observed photoproducts were CO and deltic acid dimethyl ester (C5O3H6; 2,3-dimethoxycycloprop-2-en-1-one), the latter being obtained in two different conformations (trans−trans and cis−trans). According to the experimental data, deltic acid dimethyl ester is produced by decarbonylation of the initially formed bisketene and not by direct CO extrusion from DCD. | por |
dc.language.iso | eng | por |
dc.publisher | American Chemical Society | por |
dc.rights | openAccess | por |
dc.title | Molecular Structure, Infrared Spectrum, and Photochemistry of Squaric Acid Dimethyl Ester in Solid Argon | por |
dc.type | article | por |
degois.publication.firstPage | 11034 | por |
degois.publication.lastPage | 11045 | por |
degois.publication.title | J. Phys. Chem. A, | por |
dc.peerreviewed | Yes | por |
dc.identifier.doi | 10.1021/jp0632485 | - |
degois.publication.volume | 110 | por |
uc.controloAutoridade | Sim | - |
item.fulltext | Com Texto completo | - |
item.openairecristype | http://purl.org/coar/resource_type/c_18cf | - |
item.languageiso639-1 | en | - |
item.openairetype | article | - |
item.cerifentitytype | Publications | - |
item.grantfulltext | open | - |
crisitem.author.researchunit | CQC - Coimbra Chemistry Centre | - |
crisitem.author.researchunit | CQC - Coimbra Chemistry Centre | - |
crisitem.author.parentresearchunit | Faculty of Sciences and Technology | - |
crisitem.author.parentresearchunit | Faculty of Sciences and Technology | - |
crisitem.author.orcid | 0000-0001-5983-7743 | - |
crisitem.author.orcid | 0000-0003-2896-4007 | - |
crisitem.author.orcid | 0000-0002-8264-6854 | - |
Appears in Collections: | FCTUC Química - Artigos em Revistas Internacionais |
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File | Description | Size | Format | |
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J.Physical Chemistry A, 110 (2006) 11034.pdf | 377.4 kB | Adobe PDF | View/Open |
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