Sodium cations are yellow; chloride anions are green.
This model depicts the transition state of the Diels-Alder reaction between (E)-1,3-pentadiene and acrylonitrile, shown in the equation on the right. Carbon atoms are gray, hydrogen is cyan and nitrogen is blue. The partial bonds between the C1 and C4 carbons of the diene and the double bond carbons of the dienophile are colored pink. Calculations indicate that one of these partial bonds is shorter than the other ( 2.00 vs 2.28Å ), demonstrating unsymmetrical yet concerted bond formation. Also, note the endo configuration of this transition state. The model can be rotated by clicking on the structure and dragging the mouse.
This model depicts the 2-norbornyl cation, shown on the right with dashed blue lines designating the delocalized electron pair. Note that C6 is pentacoordinate. Carbon atoms are gray and hydrogen is cyan. The model can be rotated by clicking on the structure and dragging the mouse.