Amides crystal structures

Fig. 2.28 X-ray crystal structures of parallel sheet-forming and all-un//fce-/F -peptides 116 and 117 [10, 191]. Views along the parallel amide planes and crystal packing diagram show the parallel pleated sheet arrangement (view perpendicular to the amide planes).

The bisphosphonate - upon reduction with lithiumaluminum hydride in ether at 0°C - produced the amide functionalized primary bisphosphine (1) in good yields [45]. This reaction proceeded to reduce the amide group in 1 to produce the amine functionaUzed primary bisphosphine (2) in <5% yields. The amido bisprimary phosphine 1 is an air stable crystalline solid whereas the amine compound 2 is an oxidatively stable liquid. Separation of 1 and 2 in pure forms was achieved using coliunn chromatography. The amidic bisprimary phosphine 1 was crystallized from chloroform and exhibits remarkable stability not only in the solid state but also in solution as well. The crystal structure of the air stable primary his-phosphine 1 as shown in Fig. 1 is unprecedented to date. 

Fig. 1. Crystal structure of the amide functionalized bisprimary phosphine...

Kagan and coworkers determined and studied in detail the crystal structure of a 1 1 molecular complex between (i )-methyl p-tolyl sulfoxide (10) and S)-N-(3,5-dinitrobenzoyl)-l-phenylethylamine (11). They suggested that amide 11, which had been used as a chiral solvating agent for sulfoxides, might find use as a resolving agent for these compounds. ... 

The crystal structure of a CODH/ACS enzyme was reported only in 2002.43,44 It reveals a trio of Fe, Ni, and Cu at the active site (6). The Cu is linked to the Ni atom through two cysteine-S, the Ni being square planar with two terminal amide ligands. Planarity and amide coordination bear some resemblance to the Ni porphinoid in MCR. A two-metal ion mechanism is likely for acetyl CoA synthesis, in which a Ni-bound methyl group attacks an adjacent Cu—CO fragment with formation of a Cu-acyl intermediate. A methylnickel species in CODH/ACS has been identified by resonance Raman spectroscopy.45... 

According to the PDB X-ray crystal structure 1 ao6, human serum albumin contains 69.2% o -helix and 1.7% 3io-helix, the rest being made up of turns and long loops. The amide I ROA couplet centered at 1650 cm-1 (Fig. 4), which is negative at low wavenumber and positive at high,... 

Methodical details of crystal calculations have been published by several authors (8, 95-98). As applications we only mention the calculation of the crystal structure of diphenyl (98, 99) which has a planar structure in the solid state (100) whereas gaseous diphenyl is twisted around the CC-bond, which links both benzene rings, by about 40° (101). The calculations reproduce satisfactorily the experimental findings. A further application is the calculation of the crystal structures of a series of amides (102), with the object of deriving suitable functions for the description of hydrogen bonds (cf. previous Section). 

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