π-Stacking motifs in the crystal structures of bis(phosphine) copper(I) η2-tetrahydroborate complexes

Hydrogenation reactions catalyzed by HN(CH2CH2PR2)2-ligated copper complexes

Hydrogenation of aldehydes and ketones can be catalyzed by a PNP-ligated copper hydride that is accessible from the copper borohydride or bromide complex or the copper hydride cluster.

Crystal structures of 6-chloro-indan-1-one and 6-bromo-indan-1-one exhibit different inter-molecular packing inter-actions

The two title compounds are analogs of 1-indanone that are substituted at the 6-position with chlorine and bromine. Although very similar in mol-ecular structure, the crystal structures are not isomorphous and reveal that 6-chloro-indan-1-one, C9H7ClO (I), and 6-bromo-indan-1-one, C9H7BrO (II), exhibit unique inter-molecular packing motifs. The mol-ecules of the chloro analog (I) pack with a herringbone packing motif of C-H⋯O inter-actions, whereas the bromo derivative (II) packs with offset face-to-face π-stacking, C-H⋯O, C-H⋯Br and Br⋯O inter-actions. Compound (II) was refined as a two-component non-merohedral twin, BASF 0.0762 (5).

Crystal structure of 3-bromo-2-hy-droxy-benzo-nitrile

The crystal structure of the title compound, C7H4BrNO, has been determined, revealing a partial mol-ecular packing disorder such that a 180° rotation of the mol-ecule about the phenol C-O bond results in disorder of the bromine and nitrile groups. The disorder has been parameterized as a disorder of only the bromine and nitrile substituents on a unique phenol ring. An intra-molecular O-H⋯Br contact occurs. In the crystal, O-H⋯Br/O-H⋯Nnitrile hydrogen bonding is present between the disordered bromine and nitrile substituents and the phenol group, forming a spiral chain about a twofold screw axis extending parallel to the b-axis direction. Within this spiral chain, the mol-ecules also inter-act, forming offset face-to-face π-stacking inter-actions with plane-to-centroid distance of 3.487 (1) Å.

Crystal structures of 4-chloro-pyridine-2-carbo-nitrile and 6-chloro-pyridine-2-carbo-nitrile exhibit different inter-molecular π-stacking, C-H⋯Nnitrile and C-H⋯Npyridine inter-actions

The two title compounds are isomers of C6H3ClN2 containing a pyridine ring, a nitrile group, and a chloro substituent. The mol-ecules of each compound pack together in the solid state with offset face-to-face π-stacking, and inter-molecular C-H⋯Nnitrile and C-H⋯Npyridine inter-actions. 4-Chloro-pyridine-2-carbo-nitrile, (I), exhibits pairwise centrosymmetric head-to-head C-H⋯Nnitrile and C-H⋯Npyridine inter-actions, forming one-dimensional chains, which are π-stacked in an offset face-to-face fashion. The inter-molecular packing of the isomeric 6-chloro-pyridine-2-carbo-nitrile, (II), which differs only in the position of the chloro substituent on the pyridine ring, exhibits head-to-tail C-H⋯Nnitrile and C-H⋯Npyridine inter-actions, forming two-dimensional sheets which are π-stacked in an offset face-to-face fashion. In contrast to (I), the offset face-to-face π-stacking in (II) is formed between mol-ecules with alternating orientations of the chloro and nitrile substituents.

Synthesis and crystal structure of a novel prochiral ketoimine: (E)-acetophenoneO-diphenylphosphoryl oxime

A novel activated prochiral ketoimine, (E)-acetophenoneO-diphenylphosphoryl oxime, C20H18NO2P, with an electron-withdrawing substituent on the imine N atom similar to other prochiral ketoimines, has been synthesized and the X-ray crystal stucture determined. The molecules pack together in the solid stateviaweak intermolecular C—H...O interactions and both face-to-face and edge-to-face π-stacking interactions.

Crystal structure of 4-chloro-2-iodo-aniline

In the crystal structure of the title compound, C6H5ClIN, the amino group engages in N-H⋯N hydrogen bonding, creating [100] chains. A Cl⋯I contact is observed [3.7850 (16) Å]. The parallel planes of neigbouring mol-ecules reveal highly offset π-stacking characterized by a centroid-centroid distance of 4.154 (1), a centroid-to-plane distance of 3.553 (3) and ring-offset slippage of 2.151 (6) Å.

4-Chloro-3-ethyl-phenol

The title compound, C8H9ClO, packs with two independent mol-ecules in the asymmetric unit, without significant differences in corresponding bond lengths and angles, with the ethyl group in each oriented nearly perpendicular to the aromatic ring having ring-to-side chain torsion angles of 81.14 (18) and -81.06 (19)°. In the crystal, mol-ecules form an O-H⋯O hydrogen-bonded chain extending along the b-axis direction, through the phenol groups in which the H atoms are disordered. These chains pack together in the solid state, giving a sheet lying parallel to (001), via an offset face-to-face π-stacking inter-action characterized by a centroid-centroid distance of 3.580 (1) Å, together with a short inter-molecular Cl⋯Cl contact [3.412 (1) Å].

C-shaped diastereomers containing cofacial thiophene-substituted quinoxaline rings: synthesis, photophysical properties, and X-ray crystallography

Synthesis and characterization of two diastereomeric C-shaped molecules containing cofacial thiophene-substituted quinoxaline rings are described. A previously known bis-α-diketone was condensed with an excess of 4-bromo-1,2-diaminobenzene in the presence of zinc acetate to give a mixture of two C-shaped diastereomers with cofacial bromine-substituted quinoxaline rings. After chromatographic separation, thiophene rings were installed by a microwave-assisted Suzuki coupling reaction, resulting in highly emissive diastereomeric compounds that were studied by UV-vis, fluorescence, and NMR spectroscopy, as well as X-ray crystallography. The unique symmetry of each diastereomer was confirmed by NMR spectroscopy. NMR data indicated that the syn isomer has restricted rotation about the bond connecting the thiophene and quinoxaline rings, which was also observed in the solid state. The spectroscopic properties of the C-shaped diastereomers were compared to a model compound containing only a single thiophene-substituted quinoxaline ring. Ground state intramolecular π-π interactions in solution were detected by NMR and UV-vis spectroscopy. Red-shifted emission bands, band broadening, and large Stokes shifts were observed, which collectively suggest excited state π-π interactions that produce excimer-like emissions, as well as a remarkable positive emission solvatochromism, indicating charge-transfer character in the excited state.