Selenium forms a very large number of inorganic and organic compounds
showing different reactivity and structural properties. Among them there are
hypervalent compounds, selenuranes - the derivatives in which the central selenium
atom has expanded its valence shell from 8 to 10 or 12 electrons. Such compounds are
presented in the chapter using the criterion of classification which is based on the
formal oxidation state and number (N) of ligands bonded to selenium. For each class,
the methods of synthesis, complemented with the mechanistic and stereochemical
studies, are comprehensively discussed.
Keywords: Hypervalent Selenium, Hypervalent Bonding, Selenium Trihalides,
Selenuranes, Selenurane Oxides, Perselenuranes, Spiroselenuranes,
Dihaloselenuranes, Bicyclic selenuranes, Chirality.