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The crystal structure of the orthorhombic phase I of L-cysteine, C3H7NO2S, has been determined at 30 K. The molecule adopts a gauche+ conformation and the structure consists of zwitterions connected into sinusoidal layers by N—H
O hydrogen bonds. Further N—HO hydrogen bonds connect the structure into a three-dimensional array. Under ambient conditions, the thiol H atom is disordered in such a way as to form intermolecular S—HS and S—HO hydrogen bonds. At 30 K the structure is ordered with retention of the S—HS contacts [SS = 3.8489 (4) Å, S—HS = 2.66 (3) Å and S—HS = 150.8 (16)°].
O hydrogen bonds. Further N—HO hydrogen bonds connect the structure into a three-dimensional array. Under ambient conditions, the thiol H atom is disordered in such a way as to form intermolecular S—HS and S—HO hydrogen bonds. At 30 K the structure is ordered with retention of the S—HS contacts [SS = 3.8489 (4) Å, S—HS = 2.66 (3) Å and S—HS = 150.8 (16)°].organic compoundsOpen access
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The 1:1 co-crystal of isonicotinamide and formamide, C6H6N2O·CH3NO, consists of hydrogen-bonded dimers, each comprising two isonicotinamide or two formamide molecules. These dimers are connected further by hydrogen bonds into sheets, which are parallel to the (
11) plane.
11) plane.
