They also asserted that a positively charged halogen atom is isoelectronic with oxygen and that carbon and bromine have comparable ionization potentials. For certain aryl substituted alkenes, the anti stereospecificity is diminished or lost, as a result of weakened or absent halonium character in the cationic intermediate.
The authors argued that a positively charged halogen atom has an electron configuration similar to oxygen, and that carbon and bromine have comparable ionization energies. The loss of anti stereospecificity in certain aryl substituted alkenes is attributed to weakened or absent halonium character in the cationic intermediate.