Tin–oxo clusters have attracted considerable attention because they provide a platform for studying the structure–property relationship of tin oxide materials at the molecular level. Although different types of tin–oxo clusters have been developed, extended tin–oxo cluster-based structures and their corresponding discrete clusters are rarely obtained. In this study, we regulate reaction pathways to hierarchically assemble a novel discrete Sn₈–oxo cluster and its extended structure using a solvent strategy. The discrete Sn₈–oxo cluster (CTGU-SnC-1) is obtained because its coordination active sites are occupied by the esterifiable methanol in the solvent. The resulting one-dimensional chain (CTGU-SnC-2) is formed because of the coordination-driven assembly of active sites in the Sn₈ cluster without methanol in the solvent. In addition to single-crystal X-ray diffraction, these compounds were further characterized using powder X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, elemental analysis, and ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy. In addition, their electrocatalytic CO₂ reduction properties were explored. The extended structure CTGU-SnC-2 exhibits better electrocatalytic activity than the discrete cluster in the CO₂ reduction reaction.