The molecular structure of chloromethylphosphine, CClH2PH2, as determined by gas-phase electron diffraction and ab initio computations

Article abstract of DOI:10.1016/0022-2860(94)08529-Q

The gas-phase structure of chloromethylphosphine, CClH2PH2, has been determined by electron diffraction employing constraints derived from ab initio computations at the CISD(fc)/6-31+G** level.At 293 K, the compound exists in two conformations, anti and gauche (phosphorus lone pair relative to the C-Cl bond); the mole fraction of the gauche conformer is 0.22(5).Important experimental structural parameters (r_g/pm, <*>/deg) for the anti 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-P) = 186.3(3), 187.4; r(C-Cl) = 179.1(5), 179.0; r(P-H) = 141.5(4), 142.9; PCCl = 115.7(1), 107.8(5) .The large difference between the PCCl angles in the conformers can be rationalised on the basis of overlaps between non-bonding and antibonding molecular orbitals.