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•Both (E)-β- and α-vinylgermane can obtain from HCo(CO)3 catalyzed cycle.•(E)-β-vinylgermane is obtained from the Et3GeCo(CO)3 catalyzed cycle.•The regioselectivity is determined by negative charges of C atoms of alkynes.
Transitional metal catalyzed alkynes functionalization reaction is the most atom-economical, green, and sustainable process to combine triple bonds into functional molecules. In this work, the mechanism of alkyne hydrogermylation catalyzed by Co2(CO)8 is investigated based on the DFT calculations. The calculated results show that the whole reaction involves three processes: the Co-Co bond breakage, CO dissociation, and alkyne hydrogermylation. Both (E)-β-vinylgermane and α-vinylgermane can be obtained from HCo(CO)3 catalyzed cycle, (E)-β-vinylgermane is obtained from the Et3Ge-Co(CO)3 catalyzed cycle. The regioselectivity of the alkyne hydrogermylation is determined by the negative charges on the C1 and C2 in substituted alkynes.The less negative charges on the C1 atom and the more negative charges on the C2 atom on the alkyne, the higher selectivity and yield rate of (E)-β-vinylgermane are. When the negative charge on the C1 atom is lager than that on the C2 atom, α-vinylgermane is tend to produce. Our results provide detailed explanation to the experimental results and shed light on the further development of alkyne hydrogermylation.
The mechanism of alkyne hydrogenation catalyzed by Co2(CO)8 is investigated, and how the regioselectivity regulated by the negative charges on the C atoms in alkynes is illustrated. [Display omitted]