1,15‐Penta­decane­diol

In the title compound, C₁₅H₃₂O₂, one of the terminal hydroxyl groups has a gauche conformation with respect to the hydro­carbon skeleton, while the other is trans. The mol­ecules lie parallel to the longest axis and form layers similar to those of the smectic A structure of liquid crystals. These features are similar to those of the homologues with an odd number of C atoms, but different from those with an even number.     

tert‐Butyl (3S,6R,9R)‐(5‐oxo‐3‐{[1(R)‐phenyl­ethyl]­carbamoyl}‐1,2,3,5,6,7,8,8a‐octa­hydro­indolizin‐6‐yl)­carbamate monohydrate at 95 K

The asymmetric unit of the title compound, C₂₂H₃₁N₃O₄·H₂O, incorporates one water mol­ecule, which is hydrogen bonded to the 3‐oxo O atom of the indolizidinone system. The two rings of the peptidomimetic mol­ecule are trans‐fused, with the six‐membered ring having a slightly distorted half‐chair conformation and the five‐membered ring having a perfect envelope conformation. The structure is stabilized by intermolecular O—H?O interactions between the water and adjacent peptide mol­ecules, and by N—H?O interactions between the peptide mol­ecules, which link the mol­ecules into infinite chains.     

1,21‐Henicosanediol

In the molecular structure of the title compound, C₂₁H₄₄O₂, the hydro­carbon skeleton has an all‐trans conformation. One of the terminal hydroxyl groups is also trans with respect to the skeleton, while the other is gauche. In the crystal structure, the mol­ecules lie parallel to the b axis, forming layers with a thickness of b/2. The packing is similar to that in the smectic A phase of liquid crystals. These features are similar to those of the homologues with an odd number of C atoms, but different from those with an even number.     

5‐(2‐Pyridyl)‐1,3‐di­thia­ne‐2‐thione

The title compound, C₉H₉NS₃, crystallizes with two mol­ecules in the asymmetric unit. In both mol­ecules, the di­thia­ne‐2‐thione rings adopt a symmetric half‐boat conformation with the C atom opposite the C—S_thione bond out of the plane. The pyridine ring is in an equatorial position and is twisted out of the plane of the half‐boat by 82.7 (2) and 84.5 (2)° in the two mol­ecules, so that the N atom is trans to the axial C—H bond in both cases.     

2‐Hydroxy‐3‐(3‐oxobut­yl)naphthalene‐1,4‐dione

The title compound, C₁₄H₁₂O₄, forms crystals which appear monoclinic but are actually twinned triclinic. The asymmetric unit consists of two similar mol­ecules, which differ only in the conformation of the 3‐oxobutyl side chain. The mol­ecular conformation is characterized by an intra­molecular O—H⋯O hydrogen bond between the hydroxy group and the adjacent carbonyl O atom. The crystal structure is stabilized by O—H⋯O hydrogen bonds connecting the mol­ecules into zigzag chains running along the b axis.     

(E)‐(4‐Hydroxyphenyl)(4‐nitrophenyl)diazene, (E)‐(4‐methoxyphenyl)(4‐nitrophenyl)diazene and (E)‐[4‐(6‐bromohexyloxy)phenyl](4‐cyanophenyl)diazene

Syntheses and X‐ray structural investigations have been carried out for (E)‐(4‐hydroxy­phenyl)(4‐nitro­phenyl)­diazene, C₁₂H₉N₃O₃, (Ia), (E)‐(4‐methoxy­phenyl)(4‐nitro­phenyl)­diazene, C₁₃H₁₁N₃O₃, (IIIa), and (E)‐[4‐(6‐bromo­hexyl­oxy)­phenyl](4‐cyano­phenyl)­diazene, C₁₉H₂₀BrN₃O, (IIIc). In all of these compounds, the mol­ecules are almost planar and the azo­benzene core has a trans geometry. Compound (Ia) contains four and compound (IIIc) contains two independent mol­ecules in the asymmetric unit, both in space group P (No. 2). In compound (Ia), the independent mol­ecules are almost identical, whereas in crystal (IIIc), the two independent mol­ecules differ significantly due to different conformations of the alkyl tails. In the crystals of (Ia) and (IIIa), the mol­ecules are arranged in almost planar sheets. In the crystal of (IIIc), the mol­ecules are packed with a marked separation of the azo­benzene cores and alkyl tails, which is common for the solid crystalline precursors of mesogens.     

6‐(2‐Chloro­acetamido)­hexa­noic acid

Crystals of the title compound, C₈H₁₄ClNO₃, belong to the space group Cc and are characterized by an asymmetric unit containing two mol­ecules, both with a twisted conformation. The mol­ecular packing is stabilized by N—H⋯O=C hydrogen bonds between the amide groups of mol­ecules with the same conformation. In addition, hydrogen‐bonded cyclic carboxylic acid dimers are established between mol­ecules with a different conformation. The ClCH₂—CONH bond has a cis conformation in order to favour an intra­molecular Cl⋯HN electrostatic inter­action. Weak intra‐ and inter­molecular CH₂⋯O=C inter­actions are also present.     

1,8,14,20‐Tetra­oxa‐11,23‐dithia­tricyclo­[21.3.0.09,13]hexa­cosa‐9,12,21,24‐tetra­ene

Mol­ecules of the title compound, C₂₀H₂₈O₄S₂, the first compound with a tetra­oxacyclo­hexa­cosane ring to be structurally characterized, lie on crystallographic centres of inversion, but have approximate C_2h mol­ecular symmetry. The parallel thio­phene rings are almost exactly planar; the overall conformation of the mol­ecule is chair‐like. The mol­ecules have voids that could, in principle, accommodate small guest mol­ecules, although in the crystal structure access to these voids is blocked by neighbouring mol­ecules.     

4‐[(2‐Chloro­phenyl)­diazenyl]‐6‐methoxy‐2‐{[tris­(hydroxy­methyl)­methyl]­amino­methyl­ene}cyclo­hexa‐3,5‐dien‐1(2H)‐one

The structure of the title compound, C₁₈H₂₀ClN₃O₅, displays the characteristic features of azo­benzene derivatives. Intramolecular N—H⋯O, weak intramolecular C—H⋯O, and intermolecular O—H⋯O and C—H⋯O interactions influence the conformation of the mol­ecules and the crystal packing. Intermolecular hydrogen bonds link the mol­ecules into infinite chains, and the title compound adopts the keto–amine tautomeric form. The azo­benzene moiety of the mol­ecule has a trans configuration. The mol­ecule is not planar, and the dihedral angle between the two phenyl rings is 35.6 (2)°.     

1,2,3‐Trimethoxy‐5,11‐dihydro­indolo[1,2‐b]isoquinoline‐5,11‐dione

The title compound, C₁₅H₁₉NO₅, crystallizes in the monoclinic space group P2₁/c with four mol­ecules in the asymmetric unit, which differ from each other in the orientation of their methoxy groups. Of the three methoxy groups in each molecule, one lies close to the plane of the mol­ecule and the other two have an out‐of‐plane conformation where they point in opposite directions. In the crystal structure, four different types of π‐stacks are observed and the mol­ecules pack in two different types of stacking sheets, with alternating mol­ecules A and B in one ribbon and alternating mol­ecules C and D in the other. The supramolecular structure is supported by C—H⋯O and π–π inter­actions.     

3‐Oxa‐6,8‐diaza‐1,2:4,5‐dibenzocycloocta‐1,4‐dien‐7‐one: a three‐dimensional network assembled by hydrogen‐bonding, π–π and edge‐to‐face interactions

The title compound, C₁₃H₁₀N₂O₂, is the first structure in which the urea moiety is incorporated into an eight‐membered ring. Two mol­ecules are found in the asymmetric unit, which are almost identical in their conformation and their hydrogen‐bond pattern. The carbonyl O atom acts as a double acceptor for the NH groups of two adjacent mol­ecules. In this way, infinite tapes are formed, which are connected viaπ–π and edge‐to‐face interactions in the second and third dimension. This hierarchical order of interactions is confirmed by molecular mechanics calculations. Force‐field and semi‐empirical calculations for a single mol­ecule did not find the envelope conformation present in the crystal, indicating instead a C_s conformation. Only with a model consisting of a hydrogen‐bonded dimer or a larger hydrogen‐bonded section was a conformation found that was similar to the one present in the crystal.     

Verticine ethanol hydrate (2/1/1)

The two symmetry‐independent mol­ecules of the title compound, cevane‐3β,6α,20‐triol ethanol hydrate (2/1/1), 2C₂₇H₄₅NO₃·C₂H₆O·H₂O, have the same stereochemical assignments. The six‐membered rings A, B, E and F are in the chair conformation, while ring D is in a boat conformation. The ring fusions are A/Btrans, B/Ctrans, C/Dcis, D/Etrans and E/Ftrans. The verticine mol­ecules are bridged by water and ethanol mol­ecules via hydrogen bonds to form two‐dimensional layers, and the crystal structure is built up by stacking of these layers.     

Di­methyl 9,10‐anthracenedi­carboxyl­ate: a centrosymmetric transoid molecule

In the crystal structure of the title compound, C₁₈H₁₄O₄, there are two independent mol­ecules, both of which are exactly centrosymmetric and therefore have a transoid arrangement of the ester substituents. The planes of these are inclined at 63.90 (4) and 61.02 (5)° to the anthracene central ring in the two mol­ecules because of steric interactions, preventing electronic delocalization. The observed conformation is in agreement with molecular‐modelling calculations for the isolated mol­ecule, indicating no major influence from crystal‐packing forces.     

(±)‐6‐Benzyl‐3,3‐di­methyl­morpholine‐2,5‐dione and its 5‐mono­thio and 2,5‐di­thio derivatives

The morpholine ring of the title dione, C₁₃H₁₅NO₃, shows a boat conformation that is distorted towards a twist‐boat, with the boat ends being the two Csp³ atoms of the ring. The benzyl substituent is in the favoured `exo' position. In the mono­thione derivative, (±)‐6‐benzyl‐3,3‐di­methyl‐5‐thioxo­morpholin‐2‐one, C<sub>13</sub>H<sub>15</sub>NO<sub>2</sub>S, this ring has a much flatter conformation that is midway between a boat and an envelope, with the di­methyl end being almost planar. The orientation of the benzyl group is `endo'. The di­thione derivative, (±)‐6‐benzyl‐3,3‐di­methyl­morpholine‐2,5‐di­thione, C₁₃H₁₅N­OS₂, has two symmetry‐independent mol­ecules, which show different puckering of the morpholine ring. One mol­ecule has a flattened envelope conformation distorted towards a screw‐boat, while the conformation in the other mol­ecule is similar to that in the mono­thione derivative. Intermolecular hydrogen bonds link the mol­ecules in the three compounds, respectively, into centrosymmetric dimers, infinite chains, and dimers made up of one of each of the symmetry‐independent mol­ecules.     

rac‐(Z)‐Ethyl 2‐bromo‐2‐[(3R,5R)‐3‐bromo‐5‐methyl­tetra­hydro­furan‐2‐yl­idene]acetate

In the title compound, C₉H₁₂Br₂O₃, a (tetra­hydro­furan‐2‐yl­idene)acetate, the double bond has the Z form. In the tetra­hydro­furan group, the relative configuration of the Br atom in the 3‐position and the methyl group in the 5‐position is anti. The compound crystallizes with two independent mol­ecules per asymmetric unit and, in the crystal structure, the individual mol­ecules are linked to their symmetry‐equivalent mol­ecules by C—H⋯O hydrogen bonds, so forming centrosymmetric hydrogen‐bonded dimers.     

trans‐Bis­[N‐(2‐hydroxy­ethyl)­ethyl­ene­di­amine‐κ2N,N′]­bis­(iso­thio­cyanato‐κN)­nickel(II)

The crystal structure of the title compound, [Ni(NCS)₂(C₄H₁₂N₂O)₂], has two crystallographically independent half‐mol­ecules in the asymmetric unit, with each Ni atom residing on a centre of symmetry. The two mol­ecules exhibit similar coordination geometry but display differences with regard to other structural features. Each Ni^II centre is octahedrally coordinated by two mutually trans chelating hydroxy­ethyl­ethyl­ene­di­amine ligands and two mutually trans iso­thio­cyanate ions. The two independent mol­ecules form chains through different types of non‐covalent interactions. In the case of one of the mol­ecules, only NCS and free OH groups participate in hydrogen bonding, while in the chain based on the second mol­ecule, the NCS, NH, NH₂ and free OH groups are involved in intermolecular hydrogen bonding. The two chains interact with one another through hydrogen bonding, forming planar sheets. The third packing direction is mediated only by van der Waals interactions.     

Monitoring structural transformations in crystals. 7. 1‐Chloro­anthracene and its photodimer

Crystals of the 1‐chloro­anthracene photodimer, viz. trans‐bi(1‐chloro‐9,10‐di­hydro‐9,10‐anthracenediyl), C₂₈H₁₈Cl₂, were obtained from the solid‐state [4+4]‐photodimerization of the monomer, C₁₄H₉Cl, followed by recrystallization. The symmetry of the product mol­ecules is defined by the orientation of the reactant mol­ecules in the crystal. The mutual orientation parameters calculated for adjacent monomers explain the reactivity of the compound. The mol­ecules in the crystal of the monomer and the recrystallized photodimer pack differently and the photodimer has crystallographically imposed inversion symmetry.     

Bis­[(R)‐3,5‐di­chloro‐N‐(1‐phenyl­ethyl)­salicyl­idene­aminato‐κ2N,O]­copper(II) and bis­[(R)‐3‐ethoxy‐N‐(1‐phenyl­ethyl)­salicyl­idene­aminato‐κ2N,O]copper(II)

The title compounds, [Cu(C₁₅H₁₂Cl₂NO)₂], (I), and [Cu(C₁₇­H₁₈NO₂)₂], (II), both adopt a compressed tetrahedral trans‐[CuN₂O₂] coordination geometry, the mol­ecules having an umbrella conformation overall. These complexes differ from one another with respect to the 1‐phenyl­ethyl­amine moieties, the direction of the benzene rings being either inside [in (I)] or inside and outside [in (II)] of the mol­ecules. The crystals of (I) and (II) have Δ(R,R) and Λ(R,R) absolute configurations, respectively.     

Diethyl 4‐(2,5‐di­methoxy­phenyl)‐2,6‐di­methyl‐1,4‐di­hydro­pyridine‐3,5‐di­carboxyl­ate,conformational change with solvent of crystallization

The title compound, C₂₁H₂₇NO₆, has been crystallized from ethanol containing nitro­benzene and shows the phenyl ring, B, in an ap conformation. This structure may be compared with that of the mol­ecule crystallized from ethanol alone, in which the B ring is seen in an sp conformation. The isolation of this rotamer has implications for the understanding of the docking of calcium beta‐blocking di­hydro­pyridine mol­ecules with their receptor site.     

l‐Kynureninium sulfate dihydrate

In the structure of the title compound, 2‐(3‐ammonio‐3‐carboxy­propanoyl)‐1‐anilinium sulfate dihydrate, C₁₀H₁₄N₂O₃²⁺·SO₄^2?·2H₂O, the two amino groups are proton­ated. The mol­ecule has a trans planar zigzag carbon‐skeletal conformation elongated nearly in the benzene ring plane. The two amino and the carboxyl groups are located on the same side of the mol­ecule. The crystal structure is stabilized by intermolecular hydrogen bonds involving the water mol­ecules and the sulfate ion.