Cations, crowns, and phase transfer catalysts

The following images (click image for full-size view) show potential maps (0 –> +1500), ball-and-spoke formulas, and space-filling formulas of

• (CH₃CH₂CH₂CH₂)N⁺ (top left)
• PhCH₂N(Et)₃⁺ (top center)
• 18-crown-6(K⁺) (right)
• Li⁺, Na⁺, K⁺ (bottom left)

The potentials surrounding the organic cations are more moderate, but not always for the same reason:

• The positive charge in the quarternary ammonium ions is formally assigned to N, but N is buried under a blanket of C & H. The map surface lies rather far from N so the potential on the map surface is small.
• The positive charge in the crown ether complex is assigned to K and this atom is exposed. However, the actual potential is the sum of extreme potentials generated by K and by the surrounding six O and these offset one another.