Ab initio MO calculations have been carried out on F2 HF and Cl2 HF complexes in order to shed light on the reactivities of elemental fluorine and chlorine with graphite. The results show that the F2 HF and Cl2 HF complexes are stabilized by 10.50 and 5.2kJ/mol respectively. A partial charge transfer from the halogen molecules (X2) to HF occurs. The X2 molecules are polarized and the X atoms which are not hydrogen-bonded to HF carry a partial positive charge, making the complexes suitable for the dipole-induced dipole interaction with graphite. Furthermore, the X2 molecules interacting with HF can be regarded as easily polarizable, large "soft oxidants", facilitating the subsequent charge transfer from graphite. HF plays a catalytic role both in intercalation and deintercalation processes. In contrast with fluorine, the reaction of chlorine with graphite in the presence of liquid HF barely yielded a stage-two compound after a prolonged reaction time, which was in agreement with the results of calculation. The lower reactivity of chlorine is attributed to the weaker interaction of Cl2 with HF and its smaller oxidizing ability.
ASJC Scopus subject areas
- Environmental Chemistry
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry