The vibrational spectra of COBr2, COBrCl, and COCl2

Abstract

The infra-red and Raman spectra of carbonyl bromide and carbonyl chlorobromide are reported, together with vibrational assignments for both molecules. Catalano and Pitzer's 1 new vibrational assignment for COC12 is discussed and further evidence supporting this is advanced. Thermodynamic functions for COClBr and COBr2 are given. A correlation has been established between the out-of-plane bending force constants of the carbonyl halides and has been extended to the corresponding force constants of CH20 and CH3CHO. This has been used to predict the frequencies of the out-of-plane skeletal modes of the acetyl halides.* I t would be more satisfactory to attribute this band to COClBr impurity but we see no trace of the strong 806 cm-1 band in their published infra-red spectra. t The product of the characters of v1 and Vg transforms under the operations of the point group in the same way as a rotation about an axis in the molecular plane and perpendicular to the C2 axis. As the sum-over-atoms of the cross-products of the displacement vectors for these two vibrations in non-vanishing, there will be a Coriolis coupling between the two modes. This will result in a transfer of intensity as a function of rotational quantum number and we may expect some irregularity in the band contours as a consequence of this perturbation.20 This has been neglected in the present analysis.

The Fluoroacyltris(trifluoromethyl)borate Ion, [(CF3)3BC(O)F]−, a Fluoroacylboron Complex

“…Although numerous acyl fluorides are known in organic chemistry1 no analogous isoelectronic boron compounds have been described to date. This is surprising since acyl fluorides of many nonmetals, such as hydrogen,2 nitrogen,3 sulfur,4, oxygen,4, 5 and halogens6 exist. Whereas there are no examples of fluoroacyl complexes of main‐group metals, a number of analogous coordination compounds of transition metals are known: [Ir(CO) 2 F{C(O)F}(PEt 3 )] + ,7 [Ir(CO) 5 {C(O)F}] 2+ ,8 [MF{C(O)F}(CO) 2 (PPh 3 ) 2 ] (M=Ru, Os) 9…”

Photodissociation of carbonic dibromide at 267 nm: Observation of three-body dissociation and molecular elimination of Br2

“…The Br 2 CO is prepared by the synthesis outlined previously. 24,25 The sample is purified by trap-to-trap distillation. The purity of the sample is checked by Fourier transform IR ͑FTIR͒ and UV absorption measurements.…”

Matrix isolation study of the photochemically induced reaction of ozone with dibromochloromethane and bromodichloromethane in solid argon at 14 K. FT-IR spectra of the complexes C(O)HCl · · · BrX, C(O)HBr · · · XCl, C(O)BrCl · · · HX, (OC)(HCl)(Br2), (OC)(HBr)(Cl2), and (OC)(BrCl)(HX) (where X = Br or Cl)

“…1) behave similarly, after photolysis, to those of formyl chloride and formyl bromide and were found to be at similar wavenumbers to those detected for C(O)BrCl in the gas phase. 10 Several ν C᎐ ᎐ O bands were detected after photolysis of CHBr 2 Cl and O 3 in argon matrices, those between 1824.6 and 1817.4 cm Ϫ1 being attributed to C(O)BrCl isolated in argon, the least perturbing environment. The other ν C᎐ ᎐ O bands were shifted to lower wavenumbers as a result of perturbation by the Lewis acid, HBr, and are considered to arise from the complex C(O)BrCl ؒ ؒ ؒ HBr, the shifts being of a similar magnitude to those reported for other carbonyls perturbed by HBr.…”