In this research the validity of various computational techniques has been determined and applied the appropriate techniques to investigate and propose a good catalytic system for C-H bond activation and functionalization. Methane being least reactive and major component of natural gas, its activation and conversion to functionalized products is of great scientific and economic interest in pure and applied chemistry. Thus C-H activation followed by C-C/C-X functionalization became crux of the synthesis. DFT (density functional theory) methods are well suited to determine the thermodynamic as well as kinetic factors of a reaction. The obtained results are helpful to industrial catalysis and experimental chemistry with additional information: since C-X (X = halogens) bond cleavage is important in many metal catalyzed organic syntheses, the results obtained in this research helps in determining the selectivity (kinetic or thermodynamic) advantage. When C-P bond activation is considered, results from chapter 3 indicated that C-X activation barrier is lower than C-H activation barrier. The results obtained from DFT calculations not only gave a good support to the experimental results and verified the experimentally demonstrated Ni-atom transfer mechanism from Ni=E (E = CH2, NH, PH) activating complex to ethylene to form three-membered ring products but also validated …

Two major topics that involve synthetic strategies to enhance the phosphorescence of organic and inorganic luminophores have been investigated. The first topic involves, the photophysical and photochemical properties of the gold (I) complexes LAuIX (L = CO, RNC where R = alkyl or aryl group; X = halide or pseudohalide), which have been investigated and found to exhibit Au-centered phosphorescence and tunable photochemical reactivity. The investigations have shown a clear relationship between the luminescence energies and association modes. We have also demonstrated for the first time that aurophilic bonding and the ligand p-acceptance can sensitize the photoreactivity of Au(I) complexes. The second topic involves conventional organic fluorophores (arenes), which are made to exhibit room-temperature phosphorescence that originates from spin-orbit coupling owing to either an external or internal heavy atom effect in systematically designed systems that contain d10 metals. Facial complexation of polycyclic arenes to tris[{m-(3,4,5,6-tetrafluorophenylene)}mercury(II)], C18F12Hg3 (1) results in crystalline adducts that exhibit bright RGB (red-green-blue) phosphorescence bands at room temperature. This arene-centered phosphorescence is always accompanied by a reduction of the triplet excited state lifetime due to its sensitization by accelerating the radiative instead of the non-radiative decay. The results of both topics are significant for rational design of …