A series of experiments were conducted to gain insight into the mechanism. Radical clock probes 6 and 7 were subjected to the standard conditions, yielding the cyclopropane ring-opening/coupling product 4k-2 and hept-6-enoic acid decarboxylative cyclization/coupling product 4k-3 (Figure ). These outcomes suggested the involvement of an open-shell alkyl radical generated from NHPI esters. Previous research demonstrated that racemic gem-borazirconecene alkane reagents generated the alkyl radicals under blue LEDs irradiation in a stereoconvergent manner . The combined results strongly support the hypothesis that the decarboxylative cross-coupling occurs through a radical-radical cross-coupling mechanism. Control experiments revealed that the decarboxylation could not be triggered without visible light and gem-borazirconecene alkane (Figure and Supplementary Figure ). The decarboxylative byproduct 3ab was detected without Ni-ligand complex. Light on/off experiment showed that the reactions were shut down when the blue LEDs was turn off (Supplementary Figure and), ruling out the radical chain mechanism.