Influence of Molecular Structure on the Dimerization Reactivity of Germaaromatic Compounds： a Theoretical Study

Density functional theory (DFT) calculations, at the B3LYP/6-311G** level of theory, were performed to study the reaction mechanism and potential energy surface of the 2 + 2], 4 + 2] and 4 + 4] dimerization reactions of some germaaromatic compounds. The influence of reactant's molecular structure and benzene solvent on the potential energy surface of the studied reactions was investigated. Our calculation results show that 2 + 2] and 4 + 4] reactions are concerted and synchronous processes; while 4 + 2] reactions proceed via a concerted but asynchronous way in general. 2 + 2] and 4 + 2] reactions of germabenzenes and 1-germana- phthalene proceed much more easily than the corresponding 4 + 4] reaction, both thermo- dynamically and kinetically; while most 4 + 2] paths have lower activation barrier than the corres- ponding 2 + 2] ones. As the number of six-membered aromatic rings in reactant molecules becomes larger, 2 + 2], 4 + 2] and 4 + 4] reactions become easier to proceed. The influence of substituents at the Ge atom of germabenzenes on the potential energy surface of 2 + 2] and 4 + 2] reactions correlates with their electronic properties and volume. Solvent effect is not crucial for the potential energy surfaces of the studied reactions.