Trifluoro-Aminoboranes 

Boron-Trifluoride is an inorganic compound that is used as a catalyst in chemical research and industry, forming complexes with compounds like ammonia, water and methyl alcohol. Although on the surface Boron-Trifluoride molecular complexes seem simple, much can be learned about the nature of van der Waals bonding, typical in biological systems, by studying them.

By separating the one-electron and many electron contributions in the complexation bond, we are effectively able to measure the covalent and van der Waals contributions to the bond. By observing how these contributions change as the hydrogens in the ammonia are replaced by methyl groups, we gain insight into how small changes in the chemistry of biological systems can result in large effects on how the complex behaves.

We can better understand the mechanism behind these changes by observing how the charge changes in these systems. Clearly the electron rich Methyl groups are able to increase the effective charge on the Nitrogen atom, making it more polarizable, and thus increasing its van der Waals interaction with the Boron. The covalent aspect of the bond doesn’t increase too much since the Fluorines are already saturated.

We see this charge saturation in the Fluorine manifest itself in the Nuclear Quadrupole Interactions of the Fluorines.