Showing papers by "Lester Andrews published in 1985"

Matrix reactions of silane and oxygen atoms. Infrared spectroscopic evidence for the silanol, silanone, and silanoic and silicic acid molecules

Abstract: Par photolyse, obtention de composes comportant la double liaison SiO: H 2 SiO, H(HO)SiO et (HO) 2 SiO. HSiOH est egalement prepare avec un bon rendement par decharge hyperfrequence de O 2 dans un exces d'argon. Pour les deux techniques SiH 3 OH est propose comme produit de reaction primaire par insertion d'atomes O dans une liaison SiH de SiH 4

Infrared spectroscopic evidence for silicon-oxygen double bonds: silanone and the silanoic and silicic acid molecules

Abstract: Silanon, H2SiO, wird als Zwischenverbindung bei Reaktionen mit Organosiliciumverbindungen postuliert.

FTIR observation of N≡N stretching fundamentals in hydrogen‐bonded complexes in solid argon

Abstract: Codeposition of Ar/HF and Ar/N2 samples at 10 K produced the N2‐‐H–F complex as evidenced by a very strong H–F stretching fundamental at 3881.4 cm−1 and a weak new 2332.1 cm−1 band assigned here to the N 3/4 N stretching fundamental based on 14,15N2 and 15N2 substitution. A blue DF shift to 2332. 8 cm−1 indicates a slightly stronger deuterium bond in these floppy complexes relative to the 2327.5 cm−1 Raman fundamental for N2 isolated in solid argon. Similar results were obtained for the weaker HCl and H2O complexes. Three bond stretching modes were observed for the N2‐‐H–F‐‐H–F complex.

Photolysis of hydrogen and fluorine in solid argon. Matrix infrared spectra of (HF)2, (HF) (DF), and (DF)2

Abstract: Argon diluted samples of H2 and F2 were codeposited at 10 K, and little reaction was observed. Photolysis produced a strong new 3826 cm−1 band, in agreement with assignment to (HF)2 from HF codeposition experiments, weak HF monomer and trimer bands, and a sharp new 3930 cm−1 band for the H=HF intermediate species. Sample annealing markedly increased trimer, relative to dimer and monomer, and destroyed the intermediate species. Similar experiments were done with D2 and HD; the latter gave a strong 2808 cm−1 absorption for the more stable (HF) (DF) mixed dimer and a weak 3832 cm−1 band for the less stable (DF) (HF) mixed dimer. The ability of the argon matrix cage to quench substantial reaction exothermicity is demonstrated by the preferential stabilization of (HF)2 in these experiments.

Infrared spectrum of the benzene-hydrogen fluoride complex in solid argon

Abstract: The infrared spectrum of the C/sub 6/H/sub 6/-HF complex, formed by codeposition of Ar/benzene and Ar/hydrogen fluoride samples at 12 K, exhibits strong nu/sub s/ (H-F stretching) and nu/sub 1/ (H-F librational) fundamentals at 3795 and 253 cm/sup -1/ and eight out-of-plane wagging fundamental and combination bands for the benzene submolecule in the complex. The positions of the nu/sub s/and nu/sub 1/ modes indicate a weaker complex than C/sub 2/H/sub 4/--HF, and the observation of one degenerate nu/sub 1/ mode with a nu/sub 1/(HF)/nu/sub 1/(DF) = 1.390 ratio that is characteristic of a harmonic vibration supports a C/sub 6nu/ equilibrium structure for the C/sub 6/H/sub 6/ complex, in accordance with microwave studies. 23 references, 3 figures, 3 tables.

FTIR spectra of the dimethyl ether-hydrogen fluoride complex and related complexes in solid argon

Abstract: Codeposition of argon/ether and argon/hydrogen fluoride samples at 12 K produced strong infrared bands that can be assigned to the 1:1 complex, in agreement with gas-phase spectra, allowing for matrix shifts. The matrix bands are sharp, and base submolecule absorptions were resolved from the base spectrum. Carbon-oxygen stretching fundamentals were red-shifted in the complex, which supports a complex structure with HF hydrogen bonded to a lone pair on the ether oxygen. The nu/sub x/(HF) stretching and nu/sub 1/(HF) librational modes observed for the 1:1 complex characterize a strong, relatively rigid hydrogen bond. Sample annealing produced a 1:2 complex with one stronger and one weaker hydrogen-bonded HF submolecule. 30 references, 3 figures, 2 tables.

Photochemistry of an ozone complex with iodomethane in solid argon at 17 K. Infrared spectra of iodosomethane (CH3IO) and the hydrogen-bonded CH2O--HI complex

Abstract: Codeposition of iodomethane and ozone in excess argon at 17 K leads to the formation of a molecular complex between iodomethane and ozone, which photodissociates to iodosomethane, CH/sub 3/IO, when exposed to 360-470-nm radiation in a 395-nm charge-transfer absorption band. Further photolytic rearrangement of CH/sub 3/IO gives iodomethanol (ICH/sub 2/OH), methyl hypoiodite (CH/sub 3/OI), and formaldehyde by elimination of hydrogen iodide. Because of the close proximity of the formaldehyde-hydrogen iodide molecular pair on formation, two complexes are formed; the more stable one is the hydrogen-bonded complex, CH/sub 2/O-HI, and the less stable structure yields the more stable one on sample annealing. The spectra of these CH/sub 2/O-HI complexes are free from interference by absorptions of the acid and base submolecules. 22 references, 3 figures, 5 tables.

Absorption spectra and photochemical rearrangements of C8H10 cations in solid argon. Bicyclo[2.2.2]octa-2,5-diene, cycloocta-1,3,5-triene, and octatetraene

Abstract: Matrix photoionization experiments with bicyclooctadiene and cyclooctatriene gave sharp new bands between 400 and 500 nm. Selective photolysis with visible light decreased the longer wavelength absorptions and increased a band system beginning at 447 nm; irradiation at 420-470 nm essentially restored the original spectrum. Photoionization of all-trans-octatetraene directly produced a strong 447-nm band system and a sharp weaker 756-nm band system; the latter origin and vibrational structure are in excellent agreement with the emission spectrum of the gaseous cation. Cyclooctatriene and bicyclooctadiene cations experienced a series of photochemical rearrangements, which initially gave a mixture of trans- and cis-octatetraene cations that were converted to all-trans-octatetraene cation by selective irradiation in the solid argon matrix. 23 references, 4 figures, 3 tables.

Absorption spectra and photochemical rearrangements of C10H12 radical cations in solid argon. Dicyclopentadiene, 1,3-bishomocubane, bicyclo[6.2.0]deca-2,4,6-triene, and decapentaene

Abstract: Etude detaillee et comparative des resultats. Interet particulier de l'ouverture du cycle des radicaux cationiques pour donner le cation trans-decapentaene

Evidence for alkali metal induced intermolecular acetylenic hydrogen atom transfer between hydrogen-bonded alkyne complexes in solid argon

Abstract: La condensation de l'acetylene, du propyne et de melanges butyne-2/acetylene avec les atomes de sodium, potassium et cesium dans une matrice d'argon a 15 K conduit a l'apparition d'absorptions IR dues a l'ethylene, au propene et au trans-butene-2, respectivement

Vibronic absorption spectra of fluorobenzene and difluorobenzene radical cations in solid argon

Abstract: Matrix photoionization of argon/fluoro- and difluorobenzene/ CH2Cl2 samples during condensation at 20 K produced new structured bands, which can be assigned to the parent radical cations based on agreement with differences between photoelectron bands.

Infrared spectroscopic evidence for silicon‐oxygen double bonds: silanone and the silanoic and silicic acid molecules

Abstract: Silanon, H2SiO, wird als Zwischenverbindung bei Reaktionen mit Organosiliciumverbindungen postuliert.