Please use this identifier to cite or link to this item: https://hdl.handle.net/10316/17920
DC FieldValueLanguage
dc.contributor.authorBreda, S.-
dc.contributor.authorReva, I.-
dc.contributor.authorLapinski, L.-
dc.contributor.authorFausto, R.-
dc.date.accessioned2011-12-14T16:13:12Z-
dc.date.available2011-12-14T16:13:12Z-
dc.date.issued2006-08-31-
dc.identifier.urihttps://hdl.handle.net/10316/17920-
dc.description.sponsorshipSquaric 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.isoengpor
dc.publisherAmerican Chemical Societypor
dc.rightsopenAccesspor
dc.titleMolecular Structure, Infrared Spectrum, and Photochemistry of Squaric Acid Dimethyl Ester in Solid Argonpor
dc.typearticlepor
degois.publication.firstPage11034por
degois.publication.lastPage11045por
degois.publication.titleJ. Phys. Chem. A,por
dc.peerreviewedYespor
dc.identifier.doi10.1021/jp0632485-
degois.publication.volume110por
uc.controloAutoridadeSim-
item.openairecristypehttp://purl.org/coar/resource_type/c_18cf-
item.openairetypearticle-
item.cerifentitytypePublications-
item.grantfulltextopen-
item.fulltextCom Texto completo-
item.languageiso639-1en-
crisitem.author.researchunitCQC - Coimbra Chemistry Centre-
crisitem.author.researchunitCQC - Coimbra Chemistry Centre-
crisitem.author.parentresearchunitFaculty of Sciences and Technology-
crisitem.author.parentresearchunitFaculty of Sciences and Technology-
crisitem.author.orcid0000-0001-5983-7743-
crisitem.author.orcid0000-0003-2896-4007-
crisitem.author.orcid0000-0002-8264-6854-
Appears in Collections:FCTUC Química - Artigos em Revistas Internacionais
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