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Roald Hoffmann, a renowned theoretical chemist, collaborated with Robert Woodward on groundbreaking theoretical studies. Their work focused on understanding the mechanisms and electronic structures of chemical reactions, particularly in organic chemistry. Together, they developed the Woodward-Hoffmann rules, which predict the stereochemical outcomes of pericyclic reactions based on the conservation of orbital symmetry. These rules revolutionized the field of organic chemistry and earned them the Nobel Prize in Chemistry in 1981.