Carbenium ion

A carbenium ion is a carbocation of the trivalent and classical type R₃C⁺. A carbonium ion is a carbocation of the penta- or tetracoordinated nonclassical type such as an ion of the type R₅C⁺. Carbonium ions appear as nonclassical carbocations such as the norbornyl cation. These definitions were proposed by the chemist George Andrew Olah in 1972 ^[1] and are now widely accepted. In older literature a carbocation of the type R₃C⁺ may still be referred to as a carbonium ion.

References

• ^  Stable carbocations. CXVIII. General concept and structure of carbocations based on differentiation of trivalent (classical) carbenium ions from three-center bound penta- of tetracoordinated (nonclassical) carbonium ions. Role of carbocations in electrophilic reactions George Andrew Olah; J. Am. Chem. Soc.; 1972; 94(3); 808-820. Abstract