The Substituent Effect On β-Diketoiminate Aluminacylopropene Reaction With CO

β-diketoiminate aluminacylopropene compounds, a new type, remarkable reactivity and versatile reaction patterns of organoaluminum compounds, are widespreadly taken interest by chemists in recent years. In order to study different type of substituents how to affect the reaction about CO inserting into the LA1[η2-C2R2], the quantum chemistry calculation was carried out to explore the reaction mechanism, bond character and bond order, when R is CH3, H and F, respectively. After comparing the calculation results with the crystal data, the strcture optimization method was determined to use the Gen (B3LYP/6-31G*: STO-3G) and energy computation was to employe B3LYP/6-311G**.Firstly, the reaction about CO inserting into the LAl[η2-C2R2] is a one-step process. When the substituent is CH3, an electron-donating group, its reaction potential barrier is lowest and the value is about 6.868 kcal mol-1; H by the second, energy barrier is 9.151 kcal mol-1; F atom, as an electron-attracting group, its energy barrier is the highest with the value about 10.360 kcal mol-1.Secondly, the natural bond orbital (NBO) analysis shows that there is p-πconjugate effect between the lone pair electrons in F and the double bond in the three-mumbered ring, which enhance the stability of the AIC2. Once the ring is loosened, the electronic effects of CH3 may promote the CO embedding into and form a four-membered ring. That is, the substituent effects on the reaction potential barrier may be mainly due to the hyperconjugation.Finally, NBO analysis indicates that the covalent linked Al-C will gradually change to electro-valent bond with the AIC2 ring enlarged into a six-membered ring. On the other hand, as the ring is broken, there is only electro-valent character in the Al-C.