Investigation Of Molecular Face Theory Of The Proton Transfer Processes In Malonaldehyde And Its Substituted Complexes

Molecular face?MF?is used to describe not only molecular size and shape but also its electron density.MF is called an identity card of a molecule.MF theory is employed to investigate the intramolecular proton transfer processes in malonaldehyde and its substituted complexes.For example,three-dimensional graph of PAEM,D_pb and MFs,MFSAs and MFVs are applied to investigate the reaction in malonaldehyde.The transition state and reaction route?IRC?were determined at the level of MP2/6-31++G?d,p?.The first ionization energies and HOMO energies of the forty-three points in IRC reaction route were calculated at the level of MP2/6-311++?3df,3pd?.CISD/6-31+G?d,p?in the MELD program package altogether with our own programs were carried out to calculate the PAEM of the characteristic points which are in order a?reactant?,b?7?,c?16?,d?21?,e?transition state?,f?23?,g?28?,h?37?and i?product?of intramolecular proton transfer process in malonaldehyde.The similar method was used to perform the D_pbb between atoms,to depict their MFs,to calculate their MF volumes,MF surface areas as well as the intrinsic characteristic parameters along the chemical bond and perpendicular to the molecular plane,including the boundary and the corresponding to electron density.PAEM-MO diagram was applied to investigate the intramolecular hydrogen bond in malonaldehyde.MFT was employed to study nine substituted complexes of malonaldehyde.We have obtained their transition state and IRC by using the MP2/6-31++G?d,p?.MP2/6-311++?3df,3pd?was used to calculate the first ionization energies,the activation energies of these proton transfer reactions.CISD/6-31+G?d,p?in MELD program package in combination with in-house program was carried out to calculate the single potential barrier,D_pb,between O2 and H4 atoms in reactants,to calculate MFSAs and MFVs,to display the MF graphs.We explore the relationship of D_pb between O2 and H4 atoms with the activation energy.It can be found that the bigger the D_pb is,the harder the proton transfer happens.We also investigate the IRC routes,the first ionization energies,the boundary and electron density of atomic regions O2 and H4 along the O2-H4 chemical bond involved in 3F-MA,3CH₃-MA and 1F-MA.Based on the ab initio and MFT studies of the ten molecular systems mentioned above,it can be obtained that the different substituent groups have an effect on the intramolecular proton transfer reaction in malonaldehyde.It can provide us an available theory for studying the intramolecular proton transfer reaction.