Ammonia bond distances

FIGURE 23.2 Profiles of (a) energy and FF values for nucleophilic attack and (b) for electrophilic attack for distortion in the N-H bond distance of ammonia. 

Amide resonance is a powerful stabilizing force and gives rise to a number of structural effects. Unlike the pyramidal arrangement of bonds in ammonia and amines, the bonds to nitrogen in amides lie in the same plane. The carbon-nitrogen bond has considerable double-bond character and, at 135 pm, is substantially shorter than the normal 147-pm carbon-nitrogen single-bond distance observed in amines. 

Figure 4.24. Potential energy curves for the dissociation a) of the C—N bond in protonated methylamine and b) of the B—N bond in the ammonia-borane adduct. Results of large-scale Cl calculations with all geometric parameters except the bond distance R held fixed (by permission from Michl and BonaCie-Kouteck, 1990).

The shortest Pt-bonding distances were found for negatively charged OH ligands (on average about 1.96 A). Ammonia and water coordinations are similar the average Pt-N distance is about 2.04 A and Pt-0 about 2.10 A. 

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