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)

L35.120808 cations maps.jpgL35.120808 cations ballandspokes.jpgL35.120808 cations spacefillings.jpg
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.

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