Abstract: Metallaphotoredox, including organic photoredox and transition metal catalysis, has emerged as a forceful method to realize the inert C-H bond functionalization to construct C-C or C-heteroatom bonds. In this research, the detailed mechanisms for sp³ C-H arylation and alkylation of tetrahydrofuran (THF) with aryl halide and alkyl halide catalyzed by the triplet excited diaryl ketone and nickel complex have been investigated using density functional theory calculations. The calculations indicate that the whole reaction includes three reaction processes:the formation of (THF) radical, generation of the product catalyzed by nickel catalysts (nickel catalysis), and regeneration of the Ni catalyst. The (THF) radical could be produced by the triplet ketone extracting the H atom of THF. For the nickel catalysis, NiL (L=5,5'-dimethyl-2,2'-bipyridine), not Niacac, plays an important role in the arylated reaction. In addition, the Na₂CO₃ species should be indispensable to the regeneration of NiL. Moreover, the similar results have been obtained for the sp³ C-H alkylation catalyzed by NiL' (L'=4,4'-diterbutyl-2,2'-bipyridine).

Key words: ketone catalysis, nickel catalyst, DFT, C-H arylation, C-H alkylation