Interaction of gas molecules with Ti-benzene complexes.

Using first-principles calculations based on gradient corrected density functional theory, we have studied the interaction of NH(3), H(2), and O(2) with Ti-benzene complexes [Ti(Bz)(2) and Ti(2)(Bz)(2)]. The energy barriers as the gas molecules approach the Ti-benzene complexes as well as the geometries of the ground state of these interacting complexes were obtained by starting with several initial configurations. While NH(3) and H(2) were found to physisorb on the Ti(Bz)(2) complex, the O(2) reacts with it strongly leading to dissociative chemisorption of the oxygen molecule. In contrast all the gas molecules react with the Ti(2)(Bz)(2) complex. These studies indicate that the reaction of certain, but not all, gas molecules can be used to probe the equilibrium geometries of organometallic complexes. Under special conditions, such as high pressure, the Ti atom intercalated between benzene molecules in Ti(Bz)(2) and the Ti(2)(Bz)(2) complexes could store hydrogen in chemisorbed states. The results are compared to available experimental data.