Photolysis of matrix-isolated acetyl bromide and the infrared spectrum of the 1:1 molecular complex of hydrogen bromide with ketene in solid argon

IR Structural Identification of Oxocumulene···HCl Complexes Generated in Cryogenic Matrixes. The Product-like Transition State of the Corresponding Electrophilic Addition

“…The results for 1:1 molecular complexes between ketene derivatives and HCl were obtained in earlier work at our laboratory . As was observed by Kogure et al., these complexes are characterized by a significant shift of the fundamental vibrational frequency of HCl to a lower frequency (see Table ). The purpose of the present work is to obtain direct and accurate results allowing the geometries of certain oxocumulene···HCl 1:1 complexes to be determined.…”

“…The infrared spectra were measured of the 1 ···HCl,4a the 2 ···HCl,5a and the 3 ···HCl 5b molecular complexes obtained by UV photolysis of acetyl chloride,4a cyclopropyl acid chloride,5a and chloroformylketene,5b respectively. These spectra have been described in earlier works.…”

“…The structure and potential energy surfaces of weakly bonded molecular complexes are the subject of much current experimental and theoretical study. Complexes in which the components interact through a hydrogen bond have attracted special interest, − especially the complexes between hydrogen halides and a variety of molecules (including very weak bases such as CO 2 or CO). This field has been extensively studied using molecular beams, rotational spectroscopy, 1g,i-l ab initio calculations, 1a,d,b and matrix isolation techniques. 1f,g,k,q,n,− …”

“…The sample is generally obtained by depositing or co-depositing of the gas mixture (diluted in an inert gas) on a window cooled to 20 K. Certain recent results present a noncomplicated experimental technique that consists in trapping a gas-phase mixture (i.e., aggregation, surface diffusion during deposit, etc.). In such an approach, the complexes are obtained by photodecomposition of a precursor trapped in a low-temperature matrix. − The photoproducts formed under UV irradiation are trapped in this matrix, and the cage effect prevents the photofragments from leaving the original site. This approach was used successfully to produce and identify FH···CO, HCOOH···CO,3a H 2 O···CO,3b (CH 2 ) 2 CCO···HCl,5a and H 2 CCO···HBr 4b and ···HCl 4a hydrogen-bonded complexes.…”

Breaking of Ketene Bonds during HCl Addition to Trimethylsilylketene

“…To model the complex structure, DFT calculations were carried out on several starting geometries. According to partial charges and resonance structures of ketenes, ,, two geometric arrangements are possible for the 1 :HCl complex: the L form which involves a hydrogen bond between HCl and the oxygen atom of the ketene, and the T form, in which the HCl molecule interacts with the terminal carbon atom of the ketene. The optimized structures, reported in Scheme , show that in the L form the CO bond is lengthened by 0.011 Å, while in the T form the CC bond is lengthened by 0.008 Å (the HCl molecule is in the plane of the CC π bond but is rather bound to C 3 ).…”