Selenium (Se) has an atomic number, and belongs to group 6A. So it will have 6 valence electrons. When two electrons are gained by selenium atom, it forms an anion having charge of -2.
What anion will it form and how many electrons will the ion have?
Atoms can be ionized by bombardment with radiation, but the more purely chemical process of ionization is the transfer of electrons between atoms or molecules. This transfer is driven by the stabilization that comes by obtaining stable (full shell) electronic configurations. Atoms will gain or lose electrons depending on which action takes the least energy.
Selenium ion has similar electrophilicity as halogenium ions. Accordingly, it also can induce the semipinacol rearrangement of allylic alcohols through the same pattern.
A selenium-initiated substitutive spiro annulation approach was developed and further used in the total syntheses of plumericin and allamandin by Trost et al. (Scheme 32).37 The stereoselectivity exhibited in the reaction can be rationalized as follows. The electrophilic selenium species approaches as expected from the convex face of 38 to generate an episelenonium ion 39. This allows only one rotamer to rearrange, namely the one with a trans periplanar arrangement of C–C (cyclopropane) and C–Se bonds.
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Answer:
How about selenium in the formation of ion?
Selenium (Se) has an atomic number, and belongs to group 6A. So it will have 6 valence electrons. When two electrons are gained by selenium atom, it forms an anion having charge of -2.
What anion will it form and how many electrons will the ion have?
Atoms can be ionized by bombardment with radiation, but the more purely chemical process of ionization is the transfer of electrons between atoms or molecules. This transfer is driven by the stabilization that comes by obtaining stable (full shell) electronic configurations. Atoms will gain or lose electrons depending on which action takes the least energy.
Answer:
Selenium ion has similar electrophilicity as halogenium ions. Accordingly, it also can induce the semipinacol rearrangement of allylic alcohols through the same pattern.
A selenium-initiated substitutive spiro annulation approach was developed and further used in the total syntheses of plumericin and allamandin by Trost et al. (Scheme 32).37 The stereoselectivity exhibited in the reaction can be rationalized as follows. The electrophilic selenium species approaches as expected from the convex face of 38 to generate an episelenonium ion 39. This allows only one rotamer to rearrange, namely the one with a trans periplanar arrangement of C–C (cyclopropane) and C–Se bonds.