How robust is the hydrogen-bonded amide ‘ladder’ motif?

Spectral and Structural Studies of Platinum Group Metal Complexes of3‐(Di‐2‐Pyridylaminomethyl)Benzamide and Formation of Mutual Intermolecular Hydrogen Bonding in Some Complexes

“…But because the nitrile group tends to hydrolyze, we ended up in obtaining an amide product. Among the many possible functional groups such as carboxylic acids and alcohols that can be used for the design of hydrogen‐bonded networks, amides, in particular primary amides, have been the subject of extensive studies due to the self‐complementary nature of its hydrogen‐bonded donors/acceptors, but also because of the abundance of amide moieties in biological systems 15–17. Since simple amides are known to have a free torsion angle about their hydrogen bond it leads to the formation of a range of possible structures with no obvious predictability and certainty 18…”

Herringbone array of hydrogen-bonded ribbons in 2-ethoxybenzamide from high-resolution X-ray powder diffraction

“…Occasionally, the dimers are isolated, e.g. in p-chlorobenzamide (Hayashi et al, 1980); other examples with isolated dimers include cases with rather bulky substituents (Aakeroy et al, 2007), in chlathrates (Reddy et al, 2002) and in coordination compounds (Aakeroy et al, 2005). More complex hydrogenbonding arrangements form if additional hydrogen-bonding donors or acceptors are present, e.g.…”

Structural study of picolinamide complexes of Ni(II), Zn(II), Cd(II), and Hg(II) nitrates in solid state and solution

“…Amide structures are frequently associated with an infinite ladder-like motif that is the result of a self-complementary R 2 2 (8) amide dimer accompanied by N-HÁ Á ÁO interactions between the anti hydrogen of the -NH 2 group and the carbonyl oxygen of an adjacent amide moiety producing an R 2 4 (8) motif (scheme 2) [27]. The most frequently observed hydrogen bonding motif in the crystal structures of the picolinamide complexes, R 2 4 (8) tetramer, is similar to the one formed by two pairs of N-HÁ Á ÁO interactions in the amide structures, only in the structures of picolinamide complexes, the amide oxygen is substituted by various hydrogen bonding acceptors, e.g., Cl, Br, I, N, S, from two additional adjacent molecules (scheme 1, III) forming supramolecular tetramers instead of dimers.…”