Spin-Modulated O 2 Adsorption on Surface-Constructed Metal–Organic Chains

O 2 adsorption is pivotal in O 2 -involved catalytic processes, where catalysts’ spin properties play crucial roles, yet the microscopic mechanisms remain elusive. Here, scanning tunneling microscopy/spectroscopy and atomic force microscopy characterizations enable direct comparison of O 2 affinity between the high-spin (Ni H ) and low-spin (Ni L ) Ni centers alternately embedded in the coordination chains on Au(111) at the atomic scale, revealing preferred O 2 adsorption at Ni H . Density functional theory studies demonstrate that this selectivity arises from the distinct d-electron configurations of Ni H and Ni L, which significantly affect the O 2 –Ni hybridization. The stronger O 2 adsorption at Ni H than at Ni L drives a spin transition of Ni L upon O 2 adsorption, which could be kinetically unfavorable and thus further contribute to the observed selective O 2 –Ni H binding. These findings offer microscopic insights into the spin-modulated O 2 adsorption.