An isolated complex of C 2H 4 and ICF 3 has been generated in the gas phase and studied by chirped-pulse, Fourier transform microwave (CP-FTMW) spectroscopy. Ab initio calculations at the CCSD(T)(F12)/VTZ level support the experimental work and further establish the dissociation energy, D e, and dipole moment, μ, of the complex. Rotational constants, B 0 and C 0, the centrifugal distortion constant, Δ J, nuclear quadrupole coupling constants, χ aa (I) and (χ bb(I)-χ cc(I)) and the nuclear spin-rotation coupling constant C bb(I) of the complex are determined from the experimental data. The iodine atom interacts with π-electrons on C 2H 4 resulting in the formation of a linear (∠(CI⋯)) halogen bond (where indicates the centre of the CC bond) and a complex of C s symmetry. The measured rotational constants allow the length of the halogen bond to be determined as 3.434(2) Å in the r 0 geometry. The complex is formally an asymmetric top but with a very low barrier to internal rotation of C 2H 4 about the C 3 axis defined by the CF 3I sub-unit. Adopting an approach also used in a recent study of H 2O⋯ICF 3, other transitions are assigned using the Hamiltonian of a symmetric top molecule.
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics
- Physical and Theoretical Chemistry