Wednesday, September 15, 2010

VSEPR and higher-valent systems

Based on our experience, beads are best for making trivalent systems, which should be locally flat according to the VSEPR (Valence Shell Electron Pair Repulsion) commonly used by chemists to predict 3-D structures of molecules. Molecules with unconstrained tetravalent center such as methane should be locally tetrahedral. But it is difficult to weave this kind of structures. We have only tried a few of this kind of systems.

Another situation we may like to do is constraining a tetravalent or even a pentavalent (hexavalent) bonds in a plane such as boron-boron bonds in the boron fullerenes as shown in the previous post. According to our experience, it is quite hard to keep or constrain all these bonds in a plane due to the tendency to reduce the repulsion among these bonds as required by the VSEPR.

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