For high reactivity but poor stability of homogeneous metal complexes in CO2 photoreduction, development of durable systems is still a big challenge. Herein, pentanuclear Co(II) complex [Co-5(btz)(6)(NO3)(4)(H2O)(4)] (1, btz = benzotriazolate) is explored for converting CO2 to syngas which shows high stability and reactivity in both pure and diluted CO2. Compared with mononuclear structure, multinuclear complex exhibits 212-fold enhancement in reactivity, up to similar to 2748 TONs, with wide adjustability of H-2/CO ratio from 16:1 to 2:1. This reactivity could be maintained over 200 h which is an order of magnitude higher than the durability of mononuclear complex and exceeds most reported homogeneous molecular catalysts. High reactivity is also achieved in extreme low CO2 content (5%). Structural analysis and density functional theory (DFT) calculations support that multinuclear structure and the low energy barrier for photocatalytic intermediate may account for the durable and efficient performance of complex 1. The multinuclear strategy is also adopted to nickel complex. This work probes origin of metal-node-dependent performance for CO2 photoreduction, providing new insights in design of durable and efficient metal complexes for photocatalysis and other applications. (C) 2020 Elsevier Inc. All rights reserved.