RESUMEN
The title compound, C3H7NO2*C3H8NO2+*NO3-, contains L-alanine-alaninium dimers bonded via the carboxyl groups by a strong asymmetric hydrogen bond with an O...O distance of 2.4547 (19) A. The neutral alanine molecule exists as a zwitterion, where the carboxyl group is dissociated and the amino group is protonated. The alaninium cation has both groups in their acidic form. The alanine molecule and the alaninium cation differ only slightly in their conformation, having an N-C(alpha)-C=O torsion angle close to -25 degrees. The dimers and the nitrate anion are joined through a three-dimensional hydrogen-bond network, in which the full hydrogen-bonding capabilities of the amino groups of the two alanine moieties are realised.
Asunto(s)
Alanina/química , Dipéptidos/química , Alanina/análogos & derivados , Cristalografía por Rayos X/métodos , Dimerización , Enlace de Hidrógeno , Modelos Moleculares , Conformación MolecularRESUMEN
The title compound, [Fe(3)(C(5)H(11)NO(2))(6)O(H(2)O)(3)](MnCl(4))(2)Cl(3).6H(2)O, contains a triiron core linked by a mu(3)-bridging oxide ion. Each of the iron(III) ions has a distorted octahedral environment, being coordinated, in addition to the oxide ion, by four neutral betaine molecules and one water molecule. The N-alkylated alpha-amino acid betaine is present in the dipolar zwitterionic form and chelates pairs of Fe atoms at the vertices of the triangular [Fe(3)O](7+) ionic core. The Fe complex has a crystallographically imposed D3 symmetry. The water molecules fully exhaust their potential as hydrogen donors, forming a two-dimensional hydrogen-bond network in planes parallel to (001).
RESUMEN
The title compound, C(6)H(13)NO(5), adopts a zwitterionic form where the carboxylic acid H atom is transferred to the amino group. The methyl-glycine backbone is planar. The tris(hydroxymethyl)methyl group is rotated as a rigid group around the amino-methyl bond by 22 (1) degrees and the carboxylic acid plane is rotated by 19.76 (12) degrees from the plane of the main skeleton. Apart from their H atoms, the three hydroxymethyl groups adopt a propeller-like conformation around the amino-methyl bond, close to C(3) symmetry.
RESUMEN
In the title compound, C(8)H(5)Br(2)NO(4), the endocyclic angles of the ring deviate significantly from the ideal value of 120 degrees. The substituents deviate from the plane of the ring, with large twist angles for the aldehyde, nitro and methoxy groups. The geometry of the molecule in the crystal is compared with that of the isolated molecule, as given by a self-consistent field molecular-orbital Hartree-Fock calculation. Only weak hydrogen bonds of the C-H.Br and C-H.O types are present in the crystal structure.
RESUMEN
The title compound, C(7)H(6)O(2), forms infinite chains where the molecules are hydrogen bonded via the hydroxyl and aldehyde groups, with an O.O distance of 2.719 (3) A. Interchain interactions are weak. The geometry of the ring differs from the ideal form due to the effect of the substituents. Ab initio (Hartree-Fock self-consistent field-molecular orbital and density functional theory) calculations for the free molecule reproduce well the observed small distortions of the ring. In the crystal, the geometry deviates from the ideal C(s) symmetry of the free molecule, as given by the ab initio calculations. The aldehyde and hydroxyl groups are twisted around the single bonds which join them to the ring as a result of the intermolecular hydrogen-bond interactions. These are also responsible for an elongation of the hydroxy C-OH bond compared with that calculated for the free molecule.
RESUMEN
In the title compound, C(16)H(17)NO(4), the benzyloxycarbonyl group is anti to the pyrrolic N atom. The molecules are joined into head-to-head dimers by hydrogen bonds involving the carboxylic acid groups. There is orientational disorder of these groups over two positions with approximately equal occupancy. A weaker hydrogen bond between the pyrrolic N atom and the carbonyl O atom of the benzyloxycarbonyl group joins the dimers into chains running parallel to the [110] direction.
Asunto(s)
Prolina/análogos & derivados , Pirroles/química , Cristalografía por Rayos X , Enlace de Hidrógeno , Modelos Moleculares , Conformación Molecular , Prolina/químicaRESUMEN
The title compound, C(27)H(37)N, which is intended to be included in the structure of a sulfonamide porphyrin for the preparation of Langmuir-Blodgett films, consists of a dodecyl chain linked to an anthracene molecule through an aminomethyl group. The angle between the least-squares plane of the anthracene and the dodecyl chain is 11.44 (8) degrees. The molecules are arranged in zigzag layers head-to-head, with the hydrocarbon chains side-by-side. The structure is stabilized by C-H.pi interactions, the strongest having an H.centroid distance of 2.63 A.