The molecular structure of dichloroacetyl fluoride, CCl2HCFO, as determined by gas-phase electron diffraction and ab initio computations

The gas-phase structure of dichloroacetyl fluoride, CCl2HCFO, has been determined by electron diffraction employing constraints derived from ab initio computations at the MP2/6-31 + G** level. At 293 K, the compound exists as a mixture of two conformers, trans and gauche (C-F relative to the C-H bond); the mole fraction of the gauche conformer is 0.29(5). Important experimental structural parameters (r(g) (pm), angle(alpha) (deg)) for the trans and gauche conformers respectively, are (values without e.s.d.s indicate that the difference between the parameters for the two conformers was fixed at the theoretical value): r(C-C) = 153.4(4), 154.0; r(C-Cl) = 176.8(1), 177.7 and 175.7; r(C=O) = 119.0(2), 119.1; r(C-F) = 133.6(2), 136.4; CCO = 126.4(6), 129.9; CCF = 111.6(5), 108.3; CCCl = 108.8(2), 107.0 and 110.0.