-Abstract- My presentation covers our latest results on the integrated and collaborative studies of the: (1) Solar-to-Chemical conversion including transition metal catalyzed water oxidation, designing of novel metal-to-metal charge transfer chromophores and methodology developments for interfacial electron transfer dynamics; and (2) Transition metal catalyzed C-H bond functionalization. In this talk I elaborate our efforts on understanding the transition metal catalyzed C-H bond alkylation and amination reactions. I analyze the factors controlling the mechanisms of these reactions and make intriguing predictions. Presented computational findings allowed us to gain insights into the mechanisms and important elementary steps of the presented reaction, elucidate the nature of active species, elaborate the roles of ligands and base in catalytic processes. These findings were critical for predicting/designing of new catalysts for water oxidation and C-H bond functionalization, as well as for improvement of reaction efficiency and catalyst TON.