New methods in theoretical calculations: Density functional theory and integrated MO+MM method

Recent progress in theoretical methods for the calculations of organic reactions, specially density functional theory (DFT)and integrated MO+MM (IMOMM) method, will be reviewed. DFT calculations have been performed in literature more frequently than before, in order to study organic reactions, because the DFT methods recently proposed, the hybrid methods such as B3LYP, have given accurate results comparable to expensive ab initio methods. In the IMOMM calculations, an active part of the system is handled by the MO method, the remainder is treated by the molecular mechanics force field, and the geometry is optimized fully using the sum of MO and MM energies. Thus, a large molecular system with bulky substituents could be studied theoretically. Its application to the oxidative addition of H-2 to Pt(PR3)(2) will be discussed.