1-Methyl­piperazine-1,4-diium dipicrate

In the crystal structure of the title compound [systematic name: 1-methyl­piperazine-1,4-diium bis­(2,4,6-trinitro­phen­ol­ate)], C5H14N2 2+·2C6H2N3O7 −, the ionic components are connected by relatively strong N—H⋯O hydrogen bonds into centrosymmetric six-membered conglomerates, which comprise two dications and four anions. Besides Coulombic inter­actions, only weak C—H⋯O inter­actions and some stacking between picrates (separation between the planes of ca. 3.4 Å but only a small overlapping) can be identified between these ‘building blocks’ of the crystal structure. The piperazine ring adopts a chair conformation with the methyl substituent in the equatorial position. In the picrate anions, the twist angles of the nitro groups depend on their positions relative to the phenolate O atom: it is much smaller for the NO2 groups para to the C—O− group [15.23 (9)and 3.92 (14)°] than for the groups in the ortho positions [28.76 (13)–39.84 (11)°]

2-Chloro-N-[4-chloro-2-(2-chloro­benzo­yl)phen­yl]acetamide

In the title compound, C15H10Cl3NO2, an intra­molecular N—H⋯O hydrogen bond forms a six-membered ring and enforces an almost coplanar conformation for the acetamido group, the central benzene ring and the bridging carbonyl C—C(=O)—C group: the dihedral angles between the benzene ring and the acetamide and carbonyl C—C(=O)—C planes are 7.06 (11) and 7.17 (12)°, respectively. The dihedral angle between the two benzene rings is 67.43 (9)°. Because a strong hydrogen-bond donor is involved in the intra­molecular inter­action, the crystal packing is determined by weak C—H⋯O and C—H⋯Cl inter­actions

(1RS,6SR)-Ethyl 4-(4-chloro­phen­yl)-6-(4-fluoro­phen­yl)-2-oxocyclo­hex-3-ene-1-carboxyl­ate toluene hemisolvate

In the crystal structure of the title compound, C21H18ClFO3·0.5C7H8, the toluene solvent mol­ecules occupy special positions on centres of symmetry, and consequently are disordered across this site. The cyclo­hexene ring has a slightly distorted sofa conformation; the two benzene rings are inclined by 72.90 (7)° and their planes make dihedral angles of 30.09 (10) (chloro­phen­yl) and 88.13 (6)° (fluoro­phen­yl) with the approximately planar part of the cyclo­hexenone ring [maximum deviation from plane through five atoms is 0.030 (2) Å, the sixth atom is 0.672 (3)Å out of this plane]. Weak inter­molecular C—H⋯O and C—H⋯X (X = F, Cl) inter­actions join mol­ecules into a three-dimensional structure. Also, a relatively short and directional C—Cl⋯F—C contact is observed [Cl⋯F = 3.119 (2) Å, C—Cl⋯F = 157.5 (2)° and C—F⋯Cl 108.3 (2)°]. The solvent mol­ecules fill the voids in the crystal structure and are kept there by relatively short and directional C—H⋯π inter­actions

Ethyl N-(2-benzoyl-4-chloro­phen­yl)­ethane­carboximidate

In the title compound, C17H16ClNO2, the N=C—O—C—C fragment is planar within 0.029 (1) Å, and makes dihedral angles of 66.71 (8) and 59.61 (8)° with the planes of the chloro­phenyl and benzoyl rings, respectively. The carbonyl C=O bond is not coplanar with either of the aromatic rings; it makes angles of 42.5 and 23.5° with the normals to the ring planes. In the crystal, very weak C—H⋯O, C—H⋯Cl, C—H⋯π and π–π [inter­planar distance = 3.53 (1) Å] inter­actions are observed

(E)-3-(Biphenyl-4-yl)-1-(3-bromo­phen­yl)prop-2-en-1-one

In the title compound, C21H15BrO, there are two planar rings connected through a conjugated double bond. As it crystallizes in a non-centrosymmetric space group it can be regarded as a good candidate for non-linear optical applications. The mol­ecule adopts an E configuration and the C—C=C—C torsion angle is 177.1 (4)°. The overall conformation of the compound may be described by the values of dihedral angles between the approximately planar parts. The terminal rings are twisted by an angle of 51.52 (9)°, while the biphenyl part is almost planar, the dihedral angle between the planes of the rings being 4.44 (17)°. The unit cell has one long dimension, above 35 Å, characteristic also of a majority of related compounds. The mol­ecules pack head-to-tail along this direction. C—H⋯π inter­actions are observed in the crystal structure

(2E)-1-(4-Bromo­phen­yl)-3-(4-fluoro­phen­yl)prop-2-en-1-one

The title compound, C15H10BrFO, is isostructural with (2E)-1-(4-chloro­phen­yl)-3-(4-fluoro­phen­yl)prop-2-en-1-one [Qiu et al. (2006 ▶). Acta Cryst. E62, o3525–o3526], but the structures of other dihalogen analogues, without fluorine, are different, although they are also isostructural within the series. The mol­ecule is approximately flat, the dihedral angle between the ring planes being 8.49 (13)°. In the crystal structure, inter­molecular C—H⋯O, C—H⋯F and C—H⋯Br hydrogen bonds link mol­ecules into V-shaped ribbons running parallel to [101] and stacked with an inter­planar distance of approximately 3.53 Å (centroid–vcentroid distance = 3.857 Å).

2-Isopropyl-5-methyl­cyclo­hexyl 5-acet­oxy-1,3-oxathiol­ane-2-carboxyl­ate

In the title compound, C16H26O5S, the oxathiol­ane ring adopts an envelope conformation, with the S atom 0.793 (3) Å out of the mean plane of the remaining four atoms. The cyclo­hexane ring of the menthol fragment adopts an almost ideal chair conformation, with all substituents in the equatorial positions. In the crystal, relatively strong, short and linear C—H⋯O hydrogen bonds link the mol­ecules into the chains along [100] direction. The chains are packed into the crystal structure by means of weak dispersive inter­actions. Inter­molecular C—H⋯S inter­actions are also observed

(E)-1-(2,5-Dichloro-3-thien­yl)-3-[4-(dimethyl­amino)phen­yl]prop-2-en-1-one

In the title compound, C15H13Cl2NOS, the benzene and thio­phene rings make a dihedral angle of 10.8 (1)°. The dimethyl­amino substituent and the α,β-unsaturated carbonyl group are almost coplanar with respect to the aromatic ring, forming dihedral angles of 4.73 (3)° and 5.0 (2)°, respectively. In the crystal structure, mol­ecules are connected into two-dimensional layers by weak C—H⋯Cl hydrogen bonds and C—Cl⋯O [Cl⋯O = 3.073 (2) Å] inter­actions. These layers are stacked with short C(meth­yl)–H⋯π contacts betweeen the layers

2-Methyl­imidazolium picrate

In both ionic components of the title salt, C4H7N2 +·C6H2N3O7 −, the rings are approximately planar; the maximum deviation from the mean plane is an order of magnitude larger in the picrate ring [0.0289 (10) Å] than in the imidazolium ring [0.0028 (10) Å. The nitro groups are twisted with respect to the six-atom ring plane; the NO2 groups next to the oxide O atom, at the 2- and 6-positions, are twisted more [by 53.59 (9) and 18.46 (12)°] than the NO2 group at the 4-postition, for which the twist angle is 7.28 (16)°. In the crystal, N—H⋯O hydrogen bonds, in which the hydroxyl O atom acts as a double acceptor and one of the O atoms from a nitro group acts as an additional acceptor, connect mol­ecules into chains along the c-axis direction. Relatively short C—H⋯O contacts and π–π inter­actions between symmetry-related six-membered rings [centroid–centroid distances = 3.5938 (10) and 3.6223 (10) Å] also occur