Feb 192012
 

Dalton Trans. (2012), 41, 1951-1960.    [ doi:10.1039/C1DT11758K ]

Uranium complexes of bis(p-tert-butyl-salicylidene)-1,2-diphenylethylenediamine (1) and bis(salicylidene)-1,2-diphenylethylenediamine (2) have been synthesized and investigated by X-ray single crystal diffraction and MD calculations in Periodic Boundary Conditions. Both compounds form crystals which are densely packed and do not provide voids accessible to solvent molecules. The configurations adopted by 1 and 2 are determined by well defined T-shaped and π-stacking non covalent interactions between phenyl groups of adjacent molecules as well as by a network of hydrogen bonds. These interactions and the relative arrangements of the molecules, explain the packing in the crystal structures. Each uranyl moiety shows a penta-coordination in the equatorial plane perpendicular to the trans oxygens giving rise, in both compounds, to a bypiramidal geometry. As usual for this class of compounds, the 5th position is characterized by the presence of the coordinated solvent. The in silico simulations confirm this hypothesis in very fine details. Moreover, in 1, even the partial occupancy of the solvent molecule determined from the crystal structure refinement, was shown to be due to a constrained freedom of motion of the solvent molecule that can be reproduced by molecular dynamics. This suggests that the reported disorder is not due to a poor quality of the harvested crystals but to a structural feature. In further agreement with the above mentioned results, DFT calculations demonstrated that the molecular orbital configuration and energies suit the described properties of complexes 1 and 2 suggesting a potential enantioselective activity as already shown by molecules belonging to this class of compounds.

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Feb 082012
 

Emma McKinleyEmma completed her Part II in 2011 in Chem. Cryst., but it seems we can’t get rid of her!  Ever cheerful, she brings a spark of life to the lab and has come back for a bit to encourage us to write up the outstanding papers from her thesis, in particular her work chalcones and on the modulated phase of Barluenga’s reagent.  Since her prize winning poetry performance at the BCA, we keep expecting her to start rapping…

Feb 032012
 

Acta Cryst. (2012), E68, o593-o594.    [ doi:10.1107/S1600536812003303 ]

The title compound, C7H13NO3, adopts an approximately planar conformation. The torsion angles in the aliphatic chain between the carbonyl group C atoms range from 172.97 (14) to 179.38 (14)° and the r.m.s. deviation of all non-H atoms is 0.059 Å. The crystal packing is dominated by two strong N-H···O hydrogen bonds involving the amide groups and forming R22(8) rings and C(4) chains. Overall, a two-dimensional network parallel to (100) is formed. A weak intermolecular C-H···O interaction is also present.

Hydrogen bonding in methyl 6-amino-6-oxohexanoate

Hydrogen bonding in methyl 6-amino-6-oxohexanoate

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Acta Cryst. (2012), E68, o595.    [ doi:10.1107/S1600536812003297 ]

In the title compound, C4H10NO2+·Cl-, the central ethylene bond of the cation adopts a gauche conformation. The three H atoms of the -NH3+ group are engaged in strong and highly directional intermolecular N-H···Cl hydrogen bonds, which result in a tape-like arrangement along [010] of the respective ion pairs. In addition, weak intermolecular C-H···Cl and C-H···O interactions are present.

Hydrogen bonding in 3-methoxy-3-oxopropanaminium chloride

Hydrogen bonding in 3-methoxy-3-oxopropanaminium chloride

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