Infrared spectra of the CO–H2O 1–1 cluster trapped in an argon matrix

2001 ◽  
Vol 114 (14) ◽  
pp. 6134-6141 ◽  
Author(s):  
Hisashi Abe ◽  
Koichi M. T. Yamada
Keyword(s):  
Infrared Spectra ◽  
Argon Matrix

Argon matrix Raman and infrared spectra of SF5Cl, SF5Br, and S2F10

1976 ◽  
Vol 62 (3) ◽  
pp. 449-457 ◽  
Author(s):  
R.R. Smardzewski ◽  
R.E. Noftle ◽  
W.B. Fox
Keyword(s):  
Infrared Spectra ◽  
Argon Matrix

Argon Matrix Infrared Spectroscopic Evidence for the Generation of Pentatetraenone by Flash Pyrolysis of Suitable Precursors

1988 ◽  
Vol 41 (2) ◽  
pp. 225 ◽  
Author(s):  
RFC Brown ◽  
KJ Coulston ◽  
FW Eastwood ◽  
MJ Irvine ◽  
ADE Pullin
Keyword(s):  
Carbon Atom ◽  
Infrared Spectra ◽  
Spectral Region ◽  
Narrow Band ◽  
Broad Band ◽  
Carbonyl Carbon Atom ◽  
Carbonyl Carbon ◽  
Argon Matrix ◽  
Spectroscopic Evidence ◽  
Argon Mixture

Five compounds were investigated as precursors for the pyrolytic generation of pentatetraenone, H2C=C=C=C=C=O. These were (1)-(4): 3- ethenylidenebicyclo [2.2.1]hept-5-ene with the following 2,2 substituents : H, COOCOCF3 (1); H, 13COOCOCF3 (1′); (COOCOCF3)2 (2); (COO)2C(CH3)(OCH3) (3); (COO)2Si(CH3)2 (4) and 5-(3′- methylenebicyclo [2.2.1]hept-5′-en-2′-ylidene)-2,2-dimethyl-1,3-dioxan-4,6-dione (5). The five precursors were pyrolysed in a stream of argon at temperatures in the range 350-725°C and the pyrolysate -argon mixture condensed on a CsI plate at c. 10 K. Infrared spectra were obtained between 4000 and 250 cm-1. All five precursors gave two strong bands in the spectral region 2070-2250 cm-1, possibly attributable to pentatetraenone. At lower pyrolytic temperatures the more intense of the two bands was a broad band centred at c. 2128 cm-1 [precursors (1)- (4)] or at c. 2094 cm-1 [precursor (5)]. At higher pyrolytic temperatures these bands were diminished in intensity and replaced by a narrow band at 2207 cm-1 for all five precursors. Bands due to the expected other products for each pyrolysis reaction to form pentatetraenone were observed. H2C413CO ( pentatetraenone substituted by 13C at the carbonyl carbon atom) was prepared by pyrolysis of precursor (1′). We assign the broad bands at c. 2128 cm-1 [precursors (1)-(4)] and at c. 2094 [precursor (5)] to incompletely pyrolysed precursor in which cyclopentadiene has been retained but decomposition in the rest of the molecule has resulted in formation of a =C=C=O group. Bands at 2207, 2068 and 1726 cm-1 we assign to v2-v4 of pentatetraenone. Corresponding bands at 2168, 2056 and 1720 cm-1 are observed in the spectrum of H2C413CO.

Theoretical and Experimental Studies of Enflurane. Infrared Spectra in Solution, in Low-Temperature Argon Matrix and Blue Shifts Resulting from Dimerization

2007 ◽  
Vol 111 (42) ◽  
pp. 12228-12238 ◽  
Author(s):  
Danuta Michalska ◽  
Dariusz C. Bieńko ◽  
Bogusława Czarnik-Matusewicz ◽  
Maria Wierzejewska ◽  
Camille Sandorfy ◽  
...  
Keyword(s):  
Low Temperature ◽  
Infrared Spectra ◽  
Experimental Studies ◽  
Argon Matrix

1H-1,3-Diazepines and Ketenimines from Cyanotetrazolopyridines

2008 ◽  
Vol 61 (8) ◽  
pp. 592 ◽  
Author(s):  
Chris Addicott ◽  
Curt Wentrup
Keyword(s):  
Infrared Spectra ◽  
Ring Opening ◽  
Ring Expansion ◽  
Secondary Amines ◽  
Argon Matrix ◽  
The Matrix ◽  
Nitrogen Elimination ◽  
Isolated Species

Cyano-substituted tetrazolo[1,5-a]pyridines/2-azidopyridines 8T and 15T undergo thermal ring opening to the azides 8A and 15A. Solution photolysis causes nitrogen elimination and ring expansion to 1,3-diazacyclohepta-1,2,4,6-tetraenes 10 and 17, which react with alcohols to afford 2-alkoxy-1H-1,3-diazepines, with secondary amines to 2-dialkylamino-5H-1,3-diazepines, and with water to 1,3-diazepin-2-ones (12–14, 19, 21). Argon matrix photolysis of the azides affords the diazacycloheptatetraenes 10 and 17 as principal products together with ring-opened dicyanovinylketenimines 11 and 18. The matrix-isolated species were identified on the basis of comparison of the infrared spectra with those calculated at the B3LYP/6–31+G* level.

Infrared spectra of .CCl3 and .CCl2Br isolated in an argon matrix

1969 ◽  
Vol 73 (10) ◽  
pp. 3504-3505 ◽  
Author(s):  
Jerry H. Current ◽  
Jeremy K. Burdett
Keyword(s):  
Infrared Spectra ◽  
Argon Matrix

Infrared spectra of tautomers and rotamers of 9-methylguanine. An experimental and theoretical study

1991 ◽  
Vol 69 (11) ◽  
pp. 1705-1720 ◽  
Author(s):  
K. Szczepaniak ◽  
M. Szczesniak ◽  
W. Szajda ◽  
W. B. Person ◽  
J. Leszczynski
Keyword(s):  
Absorption Spectrum ◽  
Ab Initio ◽  
Infrared Spectra ◽  
Electronic Absorption ◽  
Ab Initio Calculation ◽  
Theoretical Study ◽  
Free Energies ◽  
Argon Matrix ◽  
Tautomeric Forms ◽  
Infrared Studies

Both amino-oxo and amino-hydroxy tautomeric forms of 9-methylguanine have been identified in approximately equal abundance in. infrared studies of these molecules isolated in the hydrophobic environment of an argon matrix at 12 K. The amino-hydroxy tautomer occurs in two different rotamers correlated with the rotation of the OH group. The ratio of concentrations of the two rotamers is sensitive to UV irradiation, and this ratio then relaxes to an equilibrium value after irradiation is stopped. This sensitivity allows us to separate the experimental spectra related to the oxo tautomer and to each of the rotamers of the hydroxy tautomer. The relative concentrations of the amino-oxo and amino-hydroxy tautomers ([a-o]/[a-h] = K(o-h) = 1.0 ± 0.3) and of the two rotamers (K(h1-h2) = 0.31 ± 0.10 in an argon matrix at 12 K and about 30 ± 15 in the vapor at 470 K) are estimated from the observed relative infrared absorbances. From these relative concentrations the differences between the free energies of the tautomers (ΔG470 (o-h) = 0 ± 0.5 kJ mol−1) and of the two rotamers (ΔG(h1-h2) = 0.12 ± 0.03 kJ mol−1 in the argon matrix at 12 K and ΔG470 between +2 and −13 kJ mol−1 in the vapor at 470 K) have been estimated. The electronic absorption spectrum of 9-methylguanine isolated in the argon matrix at 12 K and the effect of brief ultraviolet irradiation on it have also been studied. In an effort to interpret the experimental results, ab initio calculations of the infrared spectra have been made for 9-methylguanine at the 3-21G//3-21G level. Comparison with the experimental spectra is of some help with the assignment of the infrared spectra for the different tautomers. Key words: 9-methylguanine, tautomerism, infrared and ultraviolet spectra, matrix isolation, ab initio calculation.

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