In the following figures are shown some examples of oxygen coordination around hydrogen. They are displayed together with calculated bond valences.
In the first figure we see a nearly symmetrical hydrogen bridge two O-H-bond near 1.2Å. Some weaker bonds add to the total bond valence sum.
Sodium hydrogen oxalate forms a very strong hydrogen bond beside 6 weaker ones.
This is now the most common situation. One primary bond with a bond valence between 0.80 to 0.90 vu and hydrogen bond in the range 0.10 to 0.15 vu. Some weaker bonds add to the complete valence.
The primary bond is nearly constant to the last example. The bond valence of the second shortest bond is now provided by the second and the third shortest bond. Of course, investigating the pictures shown, it makes no longer sense to speak of a bifurcated bond as all bonds are discribed as multifurcated.
Examples were nearly all contacts between hydrogen and sourrounding oxygens are missing are avoided by hydrogen and therefore quite rare in small molecules. Here is an example with very weak hydrogen bonds only.
Last Updated: 26 October 1996