Some coordinations around hydrogen II

In the following figures are shown some examples of oxygen coordination around hydrogen. They are displayed together with calculated bond valences.

A nearly symmetrical hydrogen bond

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.

Atom R in Å Angle Valence in vu

O13 1.195 --- 0.499

O13 1.205 174.7 0.487

O13 3.208 126.9 0.003

O13 3.253 97.6 0.003

O13 3.279 54.7 0.003

total --- --- 0.995

Atom	R in Å	Angle	Valence in vu
O13	1.195	---	0.499
O13	1.205	174.7	0.487
O13	3.208	126.9	0.003
O13	3.253	97.6	0.003
O13	3.279	54.7	0.003
total	---	---	0.995

first picture

Nearly symmetrical hydrogen bonds in lithiumhydrogenphtalate monohydrat, C₈H₅O₄Li H₂O [Küppers, Tagusagawa, Koetzle 1985]

A strong hydrogen bond

Sodium hydrogen oxalate forms a very strong hydrogen bond beside 6 weaker ones.

Atom R in Å Angle Valence in vu

O2 1.195 --- 0.739

O4 1.205 176.1 0.217

O1 3.415 68.0 0.024

O3 2.741 122.6 0.011

O2' 3.209 101.6 0.003

O1' 3.209 99.1 0.003

O4' 3.376 97.2 0.002

O5 3.712 81.7 0.001

total --- --- 1.000

Atom	R in Å	Angle	Valence in vu
O2	1.195	---	0.739
O4	1.205	176.1	0.217
O1	3.415	68.0	0.024
O3	2.741	122.6	0.011
O2'	3.209	101.6	0.003
O1'	3.209	99.1	0.003
O4'	3.376	97.2	0.002
O5	3.712	81.7	0.001
total	---	---	1.000

second picture

A strong hydrogen bond in sodium hydrogen oxalate, NaH C₂O₄ [Thomas, Olovsson 1973]

A typical hydrogen bond

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.

Atom R in Å Angle Valence in vu

O20 0.970 --- 0.871

O1 1.837 174.7 0.102

O2 2.495 126.9 0.020

O14 2.931 97.6 0.007

O10 3.680 54.7 0.001

O12 4.516 99.3 0.000

total --- --- 1.001

Atom	R in Å	Angle	Valence in vu
O20	0.970	---	0.871
O1	1.837	174.7	0.102
O2	2.495	126.9	0.020
O14	2.931	97.6	0.007
O10	3.680	54.7	0.001
O12	4.516	99.3	0.000
total	---	---	1.001

second picture

A typical hydrogen bond in lithiumhydrogenphtalate monohydrat, C₈H₅O₄Li H₂O [Küppers, Tagusagawa, Koetzle 1985]

A bifurcated hydrogen bond

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.

Atom R in Å Angle Valence in vu

O6 0.965 --- 0.881

O1 2.085 129.7 0.055

O3 2.140 139.7 0.048

O5 2.641 94.0 0.014

total --- --- 0.998

Atom	R in Å	Angle	Valence in vu
O6	0.965	---	0.881
O1	2.085	129.7	0.055
O3	2.140	139.7	0.048
O5	2.641	94.0	0.014
total	---	---	0.998

second picture

Chemical coordination with a bifurcated hydrogen bond in methyl-α-D-altropyranose [Poppelton, Jeffrey, Williams 1975]

'NO' hydrogen bonds at all

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.

Atom R in Å Angle Valence in vu

O20 0.932 --- 0.956

O2 2.959 94.6 0.006

O11 3.026 95.1 0.005

O12 3.332 65.0 0.003

O10 3.637 56.5 0.001

total --- --- 0.970

Atom	R in Å	Angle	Valence in vu
O20	0.932	---	0.956
O2	2.959	94.6	0.006
O11	3.026	95.1	0.005
O12	3.332	65.0	0.003
O10	3.637	56.5	0.001
total	---	---	0.970

second picture

Missing hydrogen bonds in lithiumhydrogenphtalate monohydrat, C₈H₅O₄Li H₂O [Küppers, Tagusagawa, Koetzle 1985]

Last Updated: 26 October 1996