UVPES and ab Initio Molecular Orbital Studies on the Electron Donor−Acceptor Complexes of Bromine with Methylamines

Abstract

The He I photoelectron spectra of bromine, methylamine, and their complex have been obtained, and the spectra show that lone-pair orbital energy of nitrogen in methylamine is stabilized by 1.8 eV and the bromine orbital energies are destabilized by about 0.5 eV due to complexation. Ab initio calculations have been performed on the charge-transfer complexes of Br2 with ammonia and methyl-, dimethyl-, and trimethylamines at the 3-21G*, 6-311G, and 6-311G* levels and also with effective core potentials. Calculations predict donor and acceptor orbital energy shifts upon complexation, and there is a reasonable agreement between the calculated and experimental results. Complexation energies have been corrected for BSSE. Frequency analysis has confirmed that ammonia and trimethylamine form complexes with C 3 v symmetry and methylamine and dimethylamine with C s symmetry. Calculations reveal that the lone-pair orbital of nitrogen in amine and the σ* orbital of Br2 are involved in the charge-transfer interaction. LANL1DZ basis seems to be consistent and give a reliable estimate of the complexation energy. The computed complexation energies, orbital energy shifts, and natural bond orbital analysis show that the strength of the complex gradually increases from ammonia to trimethylamine.

Carbazole-Bearing Porous Organic Polymers with a Mulberry-Like Morphology for Efficient Iodine Capture

“…The nitrogen atom with lone pair electrons in the frameworks made the porous adsorbent a Lewis base, which strengthen their affinity toward the iodine molecule (Lewis acid) to form a stable state. The adsorbed iodine molecular on porous adsorbents could form an outer charge complex through charge transfer between the lone pair orbital ( n ) of N atoms in the skeleton and antibonding I 2 molecular orbital (σ*) , (Figure c). This outer charge complex undergoes a transition to form an inner charge complex and then adsorbed more iodine molecules to form the polyiodide ion complex .…”

Electron States of 1:2 Addition Compounds of TiCl4with Diethyl Ether and Diethyl Sulfide: HeI Photoelectron and Electron Energy Loss Spectroscopy Studies

“…However, in the case of of diethyl sulfide with halogens, it was the π type lone pair orbital that is bonded to σ * of the halogens, the complexes having C s symmetry. 4,5 Accordingly, in this case, the minimum energy geometry of TiCl 4 -2(CH 3 ) 2 S was found to have a C 2h symmetry. The structure is optimized and is given in Figure 2b.…”

“…In this laboratory we have been investigating donor-acceptor (D-A) complexes and weakly bound hydrogen-bonded complexes by UVPES, EELS, and ab initio MO studies. [4][5][6] Recently, we have studied UVPES of 1:1 addition compounds of AlCl 3 and GaCl 3 with donors such as diethyl ether and diethyl sulfide. 7 The chlorine orbitals of AlCl 3 and GaCl 3 were found to be shifted substantially to lower binding energies, whereas donor orbitals are shifted to higher binding energies.…”

Hierarchical Porous Polymers via a Microgel Intermediate: Green Synthesis and Applications toward the Removal of Pollutants

“…The outer charge complex further formed an inner charge complex and interacted with more iodine molecules to form a polyiodide− ion complex. 63,66 The presence of polyiodide ions was proven by Raman spectra (Figure 7B). The peaks at 109 and 151 cm −1 were noted and can be assigned to the stretching vibrations of I 3 − and I 5 − , respectively.…”

“…The nitrogen atom (Lewis base) in the adsorbent interacted with iodine (Lewis acid) and formed an outer charge complex via the transfer of nonbonding/lone pair electron ( n ) of nitrogen to the vacant antibonding (σ*) orbital of the iodine molecule. The outer charge complex further formed an inner charge complex and interacted with more iodine molecules to form a polyiodide–ion complex. , The presence of polyiodide ions was proven by Raman spectra (Figure B). The peaks at 109 and 151 cm –1 were noted and can be assigned to the stretching vibrations of I 3 – and I 5 – , respectively. , Furthermore, a much larger and broad peak around 151 cm –1 indicates mostly the presence of I 5 – , which possibly explains very high iodine adsorption capacity.…”