Electron donor–acceptor complex of ICl with diethyl ether. He I photoelectron spectroscopy and ab initio molecular orbital study

The He I photoelectron spectrum of the diethyl ether–ICl complex has been obtained. The oxygen orbitals are shifted to higher binding energies and that of ICl to lower binding energies owing to complex formation. Ab initio molecular orbital (MO) calculations of the complex molecule showed that the bonding is between the σ-type lone pair of oxygen and the I atom and that the complex has C2v symmetry. The binding energy of the complex is computed to be 8.06 kcal mol–1 at the MP2/3-21G* level. The orbital energies obtained from the photoelectron spectra of the complex are compared and assigned with orbital energies obtained by MO calculations. Natural bond orbital analysis (NBO) shows that charge transfer is from the σ-type oxygen lone pair to the iodine atom and the magnitude of charge transfer is 0.0744 e.