Carbon-hydrogen bond length

The length of the carbon-hydrogen bond varies slightly with the hybridisation of the carbon atom. A bond between a hydrogen atom and an sp 2 hybridised carbon atom is about 0.6% shorter than between hydrogen and sp 3 hybridised carbon. A bond between hydrogen and sp hybridised carbon is shorter still, about 3% shorter than sp 3 C-H.

Bond Length. Bond length is defined as the distance between the centers of two covalently bonded atoms. The length of the bond is determined by the number of bonded electrons (the bond order). The higher the bond order, the stronger the pull between the two atoms and the shorter the bond length.

In this model, the hydrogen bond length, R O…N, was varied from 1.9 to 3.2 Å in 0.1 Å steps. Figure 18(A) shows the dependence of the carbonyl 17O values on the hydrogen bond lengths, that is the hydrogen bonding strengths.