Crystal structures of trans-acetyldicarbonyl(η5-cyclopentadienyl)(1,3,5-triaza-7-phosphaadamantane)molybdenum(II) and trans-acetyldicarbonyl(η5-cyclopentadienyl)(3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane)molybdenum(II)

The title compounds, [Mo(C5H5)(COCH3)(C6H12N3P)(CO)2], (1), and [Mo(C5H5)(COCH3)(C9H16N3O2P)(C6H5)2))(CO)2], (2), have been prepared by phosphine-induced migratory insertion from [Mo(C5H5)(CO)3(CH3)]. The molecular structures of these complexes are quite similar, exhibiting a four-legged piano-stool geometry with trans-disposed carbonyl ligands. The extended structures of complexes (1) and (2) differ substantially. For complex (1), the molybdenum acetyl unit plays a dominant role in the organization of the extended structure, joining the molecules into centrosymmetrical dimers through C—H...O interactions with a cyclopentadienyl ligand of a neighboring molecule, and these dimers are linked into layers parallel to (100) by C—H...O interactions between the molybdenum acetyl and the cyclopentadienyl ligand of another neighbor. The extended structure of (2) is dominated by C—H...O interactions involving the carbonyl groups of the acetamide groups of the DAPTA ligand, which join the molecules into centrosymmetrical dimers and link them into chains along [010]. Additional C—H...O interactions between the molybdenum acetyl oxygen atom and an acetamide methyl group join the chains into layers parallel to (101).

Spontaneous resolution and crystal structure of (2S)-2-(3-nitrophenyl)-3-phenyl-2,3,5,6-tetrahydro-4H-1,3-thiazin-4-one; crystal structure of rac-2-(4-nitrophenyl)-3-phenyl-2,3,5,6-tetrahydro-4H-1,3-thiazin-4-one

The crystal structures of isomeric rac-2-(4-nitrophenyl)-3-phenyl-2,3,5,6-tetrahydro-4H-1,3-thiazin-4-one (C16H14N2O3S) (1) and (2S)-2-(3-nitrophenyl)-3-phenyl-2,3,5,6-tetrahydro-4H-1,3-thiazin-4-one (C16H14N2O3S) (2) are reported here. While 1 crystallizes in a centrosymmetric space group, the crystal of 2 chosen for data collection has molecules only with (2S) chirality. This is the result of spontaneous resolution during crystallization, as the synthesis produces a racemic mixture. A crystal with (2R) molecules was also found in the same crystallization vial (structure factors available). The six-membered thiazine ring in both 1 and 2 displays an envelope conformation with the S atom forming the flap. The aryl rings in both structures adopt an approximate V shape with angles between their planes of 46.97 (14)° in 1 and 58.37 (10)° in 2. In both structures, the molecules form layers in the ab plane. Within such a layer in 1, one of the O atoms of the nitrophenyl group accepts a C—H...O hydrogen bond from the CH group at position 5 of the thiazine ring of a molecule of opposite chirality, forming chains along the a-axis direction. Each of the thiazine rings also participate in C—H...O bonds with the same carbon atom as above, resulting in chains along the b-axis direction, albeit of monochiral type. Adjacent layers are consolidated along the c-axis direction by pairs of parallel hydrogen bonds (C—H...O type) between the nitrophenyl groups of enantiomers. In 2, the two C—H...O hydrogen bonds contribute to chain formation along the b-axis direction. Weak edge-to-face interactions between the aryl groups of neighbouring molecules in 1, and C—H...π interactions between a thiazine ring CH group and a phenyl group of a neighboring molecule in 2 are also observed.

Crystal structures of μ-oxalato-bis[azido(histamine)copper(II)] and μ-oxalato-bis[(dicyanamido)(histamine)copper(II)]

The title compounds, μ-oxalato-κ4O1,O2:O1′,O2′-bis[[4-(2-aminoethyl)-1H-imidazole-κ2N3,N4](azido-κN1)copper(II)], [Cu2(C2O4)(N3)2(C5H9N3)2], (I), and μ-oxalato-κ4O1,O2:O1′,O2′-bis[[4-(2-aminoethyl)-1H-imidazole-κ2N3,N4](dicyanamido-κN1)copper(II)], [Cu2(C2O4)(C2N3)2(C5H9N3)2], (II), are two oxalate-bridged dinuclear copper complexes. Each CuIIion adopts a five-coordinate square-pyramidal coordination sphere where the basal N2O2plane is formed by two O atoms of the oxalate ligand and two N atoms of a bidentate chelating histamine molecule. The apical coordination site in compound (I) is occupied by a monodentate azide anion through one of its terminal N atoms. The apical coordination site in compound (II) is occupied by a monodentate dicyanamide anion through one of its terminal N atoms. The molecules in both structures are centrosymmetric. In the crystals of compounds (I) and (II), the dinuclear complexes are linked through N—H...Xand C—H...X(X= N, O) hydrogen bonds where the donors are provided by the histamine ligand and the acceptor atoms are provided by the azide, dicyanamide, and oxalate ligands. In compound (I), the coordinatively unsaturated copper ions interact with the histamine ligandviaa C—H...Cu interaction. The coordinatively unsaturated copper ions in compound (II) interactviaa weak N...Cu interaction with the dicyanamide ligand of a neighboring molecule. The side chain of the histamine ligand is disordered over three sets of sites in (II).

Crystal structure of 3-bromopyridineN-oxide

In the title compound, C5H4BrNO, there are two molecules in the asymmetric unit that are related by a pseudo-inversion center. The two independent molecules are approximately planar, with an observed (ring–ring) angle of 5.49 (13)°. The crystal structure exhibits a herringbone pattern with the zigzag running along theb-axis direction. The least-squares plane containing the rings of both asymmetric molecules and the plane containing the symmetrically related molecules make a plane–plane angle of 66.69 (10)°, which makes the bend of the herringbone pattern. The bromo group on one molecule points to the bromo group on the neighboring molecule, with a Br...Br intermolecular distance of 4.0408 (16) Å. The herringbone layer-to-layer distance is 3.431 (4) Å with a shift of 1.742 (7) Å. There are no short contacts, hydrogen bonds, or π–π interactions.

Crystal structure of 1-(2,4-dihydroxy-6-methylphenyl)ethanone

The title compound, C9H10O3, is a bioactive secondary metabolite, isolated from the endophytic fungusNodulisporiumsp. The compound exhibits an intramolecular O—H...O hydrogen bond between the phenolic H atom and the carbonyl O atom of the adjacent acetyl group. In the crystal, molecules are linked by hydrogen bonds involving the 4-phenolic H atom and a symmetry-related carbonyl O atom of a neighboring molecule, resulting in extended supramolecular chains along thea-axis direction. Aromatic π–π stacking interactions between the nearly parallel benzene rings of adjacent chains [centroid–centroid distance = 3.7478 (8) Å] further stabilize the three-dimensional supramolecular framework.

Crystal structure of 2-diazoimidazole-4,5-dicarbonitrile

In the title compound, C5N6, all the atoms are approximately coplanar. In the crystal, molecules are packed with short contact distances of 2.885 (2) (between the diazo N atom connected to the ring and a cyano N atom on a neighboring molecule) and 3.012 (2) Å (between the terminal diazo N atom and an N atom of a neighboring imidazole ring).

Crystal structure oftert-butyldiphenylphosphine oxide

In the structure of the title triorganophosphine oxide, C16H19OP, the P—O bond is 1.490 (1) Å. The P atom has a distorted tetrahedral geometry. The O atom interacts with both phenyl groups of a neighboring molecule [C...O = 2.930 (3) and 2.928 (4) Å]. The C—O interaction directs an extended supramolecular arrangement along thea-axis.

A cyclic carbo-isosteric penta-depsipeptide:cyclo(Phe1–D-Ala2–Gly3–Phe4–APO5)

The title compound,cyclo(Phe1–D-Ala2–Gly3–Phe4–APO5), C26H32N4O5, is the minor diastereoisomer of a cyclic penta-peptidomimetic analogue containing a novel 2-aminopropyl lactone (APO) motif, which displays the same number of atoms as the native amino acid glycine and has a methyl group in place of the carbonyl O atom. The crystal structure presented here allows the analysis of the secondary structure of this unprecedented cyclic carbo-isosteric depsipeptide. The conformation of the central ring is stabilized by an intramolecular N—H...O hydrogen bond between the carbonyl O atom of the first residue (Phe1) and the amide group H atom of the fourth residue (Phe4). Based on the previously reported hydrogen bond and on the values of the torsion angles ϕ and ψ, the loop formed by the first, second, third and fourth residues (Phe1, D-Ala2, Gly3and Phe4) can be classified as a type II′ β-turn. The loop around the new peptidomimetic motif, on the other hand, resembles an open γ-turn containing a weak N—H...O hydrogen bond between the carbonyl group O atom of the fourth residue (Phe4) and the amide unit H atom of the first residue (Phe1). In the crystal, the peptidomimetic molecules are arranged in chains along theb-axis direction. Within such a chain, the molecules of the structure are linkedviaN—H...O hydrogen bonds between the amide group H atom of the secondary residue (D-Ala2) and the carboxy unit O atom of the fourth residue (Phe4) in a neighboring molecule. The newly formed methyl stereocentre of the APO peptidomimetic motif (APO5) was obtained as the minor diastereoisomer in a ring-closing reductive amination reaction and adopts anRconfiguration.

Regulation of Influenza A Virus Nucleoprotein Oligomerization by Phosphorylation

In the influenza virus ribonucleoprotein complex, the oligomerization of the nucleoprotein is mediated by an interaction between the tail-loop of one molecule and the groove of the neighboring molecule. In this study, we show that phosphorylation of a serine residue (S165) within the groove of influenza A virus nucleoprotein inhibits oligomerization and, consequently, ribonucleoprotein activity and viral growth. We propose that nucleoprotein oligomerization in infected cells is regulated by reversible phosphorylation.