Infrared Spectra of the Chloromethyl and Bromomethyl Cations in Solid Argon

Abstract

Infrared spectra of chloromethyl and bromomethyl cations isolated in solid argon are reported. Cocondensation of dichloromethane and dibromomethane with high-frequency discharged argon at 4 K produces the dichloromethane and dibromomethane cations, which dissociate upon visible light irradiation to form the chloromethyl and bromomethyl cations. On the basis of isotopic substitutions ((13)C and deuterium) as well as theoretical frequency calculations, photosensitive absorptions are assigned to different vibrational modes of the chloromethyl and bromomethyl cations. Theoretical calculations predict that the halomethyl cations have a planar C(2v) symmetry with a shorter C-X bond and longer C-H bonds relative to those of the halomethyl free radicals.

Syntheses, Structures, and Electronic Properties of the Branched Oligogermanes (Ph3Ge)3GeH and (Ph3Ge)3GeX (X = Cl, Br, I)

“…The [CH 2 Cl þ ] cation has been identified by infrared spectroscopy as a discrete molecule in an argon matrix. 72 The crude product mixture was suspended in benzene and filtered to remove excess…”

“…The cation (Ph 3 Ge) 3 Ge + generated in the reaction subsequently abstracts a chlorine atom from the CH 2 Cl 2 solvent to provide 3 , with [CH 2 Cl + ][PF 6 − ] being generated as a byproduct. The [CH 2 Cl + ] cation has been identified by infrared spectroscopy as a discrete molecule in an argon matrix …”

Gas-Phase Infrared Action Spectroscopy of CH2Cl+ and CH3ClH+: Likely Protagonists in Chlorine Astrochemistry

“…The situation for X=Br, for example, appears similar to the one with X=Cl prior to the present study. To date, spectroscopic studies of CH 2 Br + have been restricted to infrared matrix isolation [12,54]. Protonated methyl bromide, CH 3 BrH + , seems not to have been spectroscopically studied to date.…”

“…Theoretical molecular structures of both CH 2 Cl + (C 2v ) and CH 3 ClH + (C s ) have previously been provided on several occasions (e.g., Refs. [12,[22][23][24][25]). In the present study, complementary quantum-chemical calculations of CH 2 Cl + and CH 3 ClH + (as well as their isostructural and isoelectronic sulfur analogs, H 2 CS and CH 3 SH) were performed at the coupled cluster single and double (CCSD) level augmented by a perturbative treatment of triple excitations (CCSD(T)) [26], together with correlation-consistent (augmented) polarized valence and (augmented) polarized weighted core-valence basis sets, i.e., cc-pVXZ [27], aug-cc-pVXZ [27][28][29], and cc-pwCVXZ [27,30] (with X = T, Q).…”

“…Photoelectron spectroscopy of the CH 2 Cl radical has provided a vibrational wavenumber ν = 1040(30) cm −1 of the Cl-C-stretching mode of CH 2 Cl + [10,11]. A somewhat more comprehensive picture of the vibrational spectrum has been obtained through infrared spectroscopy of CH 2 Cl + trapped in solid Ar matrices [12]. In these studies, four out of the six vibrational fundamentals were observed for the most abundant isotopic species, CH 2 35 Cl + .…”