These two compounds exhibit a stereoisomeric relationship.
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memory
Parse it as 立体 (lìtǐ, three-dimensional) + 异构 (yìgòu, different structure). Contrast with 构造异构 (gòuzào yìgòu, constitutional isomerism, where the connectivity itself differs).
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Specialist chemistry term. The thalidomide tragedy of the late 1950s is the classic real-world cautionary tale of why stereoisomerism matters: one mirror-image enantiomer was therapeutic, the other caused birth defects.
