We present spin-coupled valence bond calculations on the reaction pathway for the insertion of a methyl cation onto the aromatic system of benzene, leading to the Wheland intermediate C6H6CH3+. Simultaneously with the geometrical rehybridization of the two carbons forming the new substrate-electrophile bond (from sp(2) to sp(3)), we observe the crossing of two spin-coupled potential energy curves; at large separations, these correspond to C6H6 + CH3+ and to C6H6+ + CH3. In the neighborhood of the crossing point, the spin-coupled valence bond wave function obtained by mixing these two orbital configurations switches continuously from the former to the latter.