Exploring Electronic Structure and Reactivity with Density Functional Theory and Principal Interacting Orbital Analysis

Principal Interacting Orbital analysis makes use of Natural Atomic Orbital and identify the orbitals with maximum interaction, which was used extensively in the thesis for bonding analysis. In the first project, we continued previous studies on inter-ligand delocalization and investigated the role of transition metal center on inter-ligand delocalization. It was found that inter-ligand delocalization is facilitated by p orbitals of late transition metal center, illustrated by the example of Li4Pd(C4R4)2, while d orbital of early transition metal center is used due to the high energy of p orbitals of early transition metal, which was illustrated by the example of V(C2H2S2)3. Inter-ligand delocalization also requires the symmetry matching between electron-accepting orbital of metal center and the LGOs, which is shown by the geometric difference between Ni(C2H4)3 and Ni(COD)22-. In the second project, we would use NLMO, QTAIM and PIO analyses to investigate the bonding of a zinc-boryl complex, which reveals that the electrophilicity and nucleophilicity are associated with the empty p orbital of boron and Zn-B σ bond, respectively. DFT calculation was used to find out the reaction mechanism between zinc boryl complex with DCC and azobenzene respectively. PIO analysis further revealed the involvement of neighboring C=N π* orbital in the nucleophilic attack of DCC, and the unconventional participation of phenyl ring in the reaction of azobenzene.