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.     

A pseudosymmetric triclinic modification of tri­phenyl­tin iso­propyl­xanthate

All three independent mol­ecules in the triclinic modification of (O‐iso­propyl di­thio­carbonato‐S)­tri­phenyl­tin, [Sn(C₆H₅)₃(C₄H₇OS₂)], show tetrahedral coordination at their Sn atoms. Bond dimensions involving the Sn atoms are similar to those found in the monoclinic modification of the same compound. Two of the independent mol­ecules are related by a pseudo‐translation allowing a stacking fault that reduces the intensities of h + k odd reflections.     

A [4π+4π] intramolecular photocyclomer of 9‐anthroic anhydride: 5,6,11,12‐tetrahydro‐5,12;6,11‐di‐o‐­benzenodibenzo[a,e]cyclooctene‐5,6‐dicarboxylic anhydride

The title compound, C₃₀H₁₈O₃, was obtained by light irradiation of a di­chloro­ethane solution of 9‐anthroyl chloride and 9‐anthroic acid. The mol­ecules, which possess approximately mm2 local symmetry, are packed in columns, the oxy­genated moieties facing each other according to the symmetry of a monoclinic lattice. The space group of the crystal is P2₁/c, with a whole mol­ecule as the asymmetric unit. The structure is compared with those of similar dianthracene derivatives.     

[(η5‐C5R5)TiCl2(η5‐C5H4SiMe2)]2O·nCH2Cl2

The first title metallocene, 1,3‐bis(dichlorotitanocene)‐1,1,3,3‐tetramethyldisiloxane dichloromethane solvate, [(η⁵‐C₅H₅)­TiCl₂­(η⁵‐C₅H₄­Si­Me₂)]₂O·­CH₂Cl₂, (I), crystallizes in space group P2₁/c. Compound (I) represents the first crystal structure of a bimetallic siloxy‐bridged titanocene. The geometric parameters of (I) are similar to those of the parent titanocene; however, the disiloxane substituents adopt an unexpected eclipsed conformation. The second title metallocene, 1,3‐bis­[(penta­methyl­cyclo­penta­dienyl)­(cyclo­penta­dien­yl)­titanium dichloride]‐1,1,3,3‐tetra­methyl­disiloxane, [(η⁵‐C₅‐Me₅)­TiCl₂­(η⁵‐C₅H₄­Si­Me₂)]₂O, (II), represents the second crystal structure of a bimetallic siloxy‐bridged titanocene and crystallizes in the space group P2₁/n. Compound (I) possesses non‐crystallographic twofold molecular symmetry and both metal centers adopt pseudo‐tetrahedral geometries. The geometric parameters of (II) are similar to those of the mixed titanocene Cp*CpTiCl₂ (Cp* = C₅Me₅) and the disiloxane substituents adopt a staggered conformation.     

Tetrakis­(tetra­hydro­furan‐κO)­lithium mer‐tris­(carbazolyl‐κN)‐trans‐di­chloro(tetra­hydro­furan‐κO)­zirconate

In the title compound, [Li(C₄H₈O)₄][ZrCl₂(C₁₂H₈N)₃(C₄H₈O)], the environment of the Zr atom is pseudo‐octahedral, with the three carbazolyl ligands in a mer configuration. The counter‐ion of the zirconium complex is composed of an Li atom surrounded by four tetra­hydro­furan (THF) mol­ecules. The THF mol­ecule attached to the Zr atom is disordered over two sites, as are two of the THF mol­ecules in the lithium moiety. All bond distances and angles are consistent with those in complexes with similar structural entities. The Zr—N bond distances are 2.2185 (18) and 2.167 (3) Å.     

The effects of substitution on tetrakis­(substituted imidazole)­copper(II) tri­fluoro­methane­sulfonates

The organic ligands 4‐methyl‐1H‐imidazole and 2‐ethyl‐4‐methyl‐1H‐imidazole react with Cu(CF₃SO₃)₂·6H₂O to give tetrakis(5‐methyl‐1H‐imidazole‐κN³)­cop­per(II) bis­(tri­fluoro­methane­sulfonate), [Cu(C₄H₆N₂)₄](CF₃SO₃)₂, and aqua­tetrakis(2‐ethyl‐5‐methyl‐1H‐imidazole‐κN³)copper(II) bis(tri­ fluoro­methane­sulfonate), [Cu(C₆H₁₀N₂)₄(H₂O)](CF₃SO₃)₂. In the former, the Cu atom has an elongated octahedral coordination environment, with four imidazole rings in equatorial positions and two tri­fluoro­methane­sulfonate ions in axial positions. This conformation is similar to those in the analogous complexes tetrakis­(imidazole)­cop­per(II) tri­fluoro­methane­sulfonate and tetrakis(2‐methyl‐1H‐imidazole)­cop­per(II) tri­fluoro­methane­sulfonate. In the second of the title compounds, the ethyl groups block the central Cu atom, and a square‐pyramidal coordination environment is formed around the Cu atom, with the substituted imidazole rings in the basal positions and a water mol­ecule in the axial position.     

2,4,5,7‐Tetra­methyl­phenanthrene at 150 K

The title compound, C₁₈H₁₈, crystallized in the centrosymmetric space group P2₁/c with one mol­ecule as the asymmetric unit. The methyl‐group H atoms at the 4 and 5 positions are ordered, while those at the 2 and 7 positions are disordered. The torsion of the bay region of the core is notably similar to that of other 4,5‐di­methyl­phenanthrenes. No substantial C—H?π interaction occurs in this structure.     

1,17‐Hepta­decane­diol

In the title compound, C₁₇H₃₆O₂, one of the hydroxyl groups has a gauche conformation with respect to the hydro­carbon skeleton, which is all‐trans, whereas the other has a trans conformation. The molecular shape is rod‐like and the compound has a rotator phase in which mol­ecules are assured greater motional freedom, as in liquid crystals. In addition, the mol­ecules arranged along the longest axis, b, form layers which are very similar to those of the smectic A liquid crystals.     

tert‐Butyl (6S)‐4‐hydroxy‐6‐isobutyl‐2‐oxo‐1,2,5,6‐tetra­hydropyridine‐1‐carboxyl­ate and tert‐butyl (4R,6S)‐4‐hydroxy‐6‐iso­butyl‐2‐oxopiperidine‐1‐carboxyl­ate

X‐ray studies reveal that tert‐butyl (6S)‐6‐iso­butyl‐2,4‐dioxo­piperidine‐1‐carboxyl­ate occurs in the 4‐enol form, viz. tert‐butyl (6S)‐4‐hydroxy‐6‐iso­butyl‐2‐oxo‐1,2,5,6‐tetra­hydropyri­dine‐1‐carboxyl­ate, C₁₄H₂₃NO₄, when crystals are grown from a mixture of di­chloro­methane and pentane, and has an axial orientation of the iso­butyl side chain at the 6‐position of the piperidine ring. Reduction of the keto functionality leads predominantly to the corresponding β‐hydroxy­lated δ‐lactam, tert‐butyl (4R,6S)‐4‐hydroxy‐6‐iso­butyl‐2‐oxo­piperidine‐1‐car­boxyl­ate, C₁₄H₂₅NO₄, with a cis configuration of the 4‐hydroxy and 6‐iso­butyl groups. The two compounds show similar molecular packing driven by strong O—H⋯O=C hydrogen bonds, leading to infinite chains in the crystal structure.     

A uranyl ion complex of N‐methyl‐p‐tert‐butyl­dihomo­ammonio­calix­[4]­arene with di­aqua­di­pyridine­lithium as counter‐ion

The title complex, di­aqua­di­pyridine­lithium (N‐methyl‐p‐tert‐butyl­dihomo­ammonio­calix­[4]­arene‐κ⁴O)­dioxouranium(VI) tri­pyridine solvate monohydrate, [Li(C₅H₅N)₂(H₂O)₂][UO₂(C₄₆H₅₈NO₄)]·3C₅H₅N·H₂O, contains an `internal' tetraphenoxide‐coordinated uranyl complex of the macrocycle, in which the protonated N atom is involved in an intramolecular hydrogen bond with the uranyl oxo group located in the cavity. The Li⁺ ion is in a tetrahedral environment and its two water ligands are involved in hydrogen bonds with two phenoxide O atoms, two pyridine mol­ecules and one water mol­ecule. This arrangement is compared with those obtained previously for other homo­aza­calixarenes and also for homo­oxa­calixarenes in the presence of alkali metal hydro­xides.     

N,N′‐Bis(2‐methoxy­benzyl­idene) adducts of ethane‐1,2‐di­amine,propane‐1,3‐di­amine and butane‐1,4‐di­amine

We have isolated and crystallographically characterized the three homologous compounds N,N′‐bis(2‐methoxy­benzyl­idene)­ethane‐1,2‐di­amine (MeSalen), C₁₈H₂₀N₂O₂, N,N′‐bis(2‐methoxy­benzyl­idene)­propane‐1,3‐di­amine (MeSalpr), C₁₉H₂₂N₂O₂, and N,N′‐bis(2‐methoxy­benzyl­idene)­butane‐1,4‐di­amine (MeSalbu), C₂₀H₂₄N₂O₂. In contrast with MeSalpr, the mol­ecules of MeSalen and MeSalbu, which have an even number of methyl­ene units, have crystallographic symmetry. Comparing these methoxy‐substituted species with their hydroxy equivalents shows that the aryl rings rotate upon removal of the O—H⋯N hydrogen bonds. The packing of MeSalen and MeSalpr is controlled by C—H⋯π interactions, whereas that of MeSalbu has only van der Waals contacts.     

Two isomeric di­deoxy­nucleosides

We have synthesized two isomeric di­deoxy­nucleosides. 4(S)‐(6‐Amino‐9H‐purin‐9‐yl)‐3‐methyl­ene‐2,3,4,5‐tetra­hydrofuran‐2(S)‐yl­methanol, C₁₁H₁₃N₅O₂, is an analogue of the anti‐HIV compound (S,S)‐isodi­deoxy­adenosine (isoDDA) with an exocyclic methyl­ene group and is found to be anti‐HIV inactive. The solid‐state comformation is very similar to that of isoDDA. 4(S)‐(6‐Amino‐3H‐purin‐3‐yl)‐3‐methyl­ene‐2,3,4,5‐tetra­hydro­furan‐2(S)‐ylmethanol, C₁₁H₁₃N₅O₂, has an isomeric arrangement of the carbohydrate and base moieties, as confirmed by the crystal structure analysis. The asymmetric unit contains two independent mol­ecules that differ in conformations at the sugar moiety.     

Tri­benzyl{η5‐[2‐(p‐tolyl)­prop‐2‐yl]­cyclo­penta­dienyl}­zirconium

The title compound, [Zr(C₇H₇)₃(C₁₅H₁₇)], (I), crystallizes from light petroleum with two independent mol­ecules in the asymmetric unit. Whereas in the parent mol­ecule, Zr(η⁵‐C₅H₅)(CH₂Ph)₃, all three Zr—CH₂Ph angles are equal, in (I), they differ significantly. In spite of their different environments, both independent mol­ecules in (I) exhibit a small, an expected, and a large Zr—CH₂Ph angle. The angles are similar to those of the closely related tri­benzyl­[η⁵‐(benzyl­di­methyl­silyl)­cyclo­penta­dienyl]­zirconium complex. The smallest Zr—CH₂Ph angle and the consequently relatively short Zr?C_ipso distance are indicative of η²‐bonding of the benzyl group.     

Four 3‐cyano­difur­aza­nyl ethers: potential propellants

In earlier papers, we described the synthesis and structures of bis(3‐nitro­fur­azan‐4‐yl) ether, C₄N₆O₇, (I), bis­[3‐(nitro‐N,N,O‐azoxy)­fur­azan‐4‐yl] ether, C₄N₁₀O₉, (II), and bis[3‐­(5H‐[1,2,3]­triazolo­[4,5‐c]­fur­azan‐5‐yl)­fur­azan‐4‐yl] ether, C₈N₁₄O₅, (III). Here we compare the structures of (I)–(III) with those of four 3‐cyano­difur­aza­nyl ethers, namely bis(3‐­cyano­fur­azan‐4‐yl) ether, C₆N₆O₃, (IV), 3‐cyano­fur­aza­nyl 3‐­nitro­fur­aza­nyl ether, C₅N₆O₅, (V), 3,4‐bis(3‐cyano­fur­azan‐4‐­yl­oxy)­fur­azan, C₈N₈O₅, (VI), and bis­[3‐(3‐cyano­fur­azan‐4‐­yl­oxy)­fur­azan‐4‐yl]­diazene, C₁₀N₁₂O₆, (VII). It was found that the geometric parameters of the difur­aza­nyl ether fragments are similar in these structures and therefore not influenced by substituent effects; however, the conformation of this fragment is different, viz. structures (I), (III), (V) and (VI) have approximate C₂ symmetry, and structures (II), (IV) and (VII) have C_s symmetry. Dense crystal packing (1.626–1.898 Mg m⁻³) is characteristic for all these hydrogen‐free compounds. A linear correlation is also determined between crystal density and `molecular density' (M/V), where M is the mass of a mol­ecule and V is the molecular volume.     

N‐Propionyl‐1,2‐benzisoselenazol‐3(2H)‐one

The title compound, C₁₀H₉NO₂Se, crystallizes as flat mol­ecules linked by selenium–oxy­gen interactions [Se?O = 3.189 (4) Å] into a linear chain along the a axis of the triclinic cell. The bond dimensions that are derived from ab initio geometry optimization calculations are similar to those determined from the diffraction measurements.     

Chalcone epoxide inter­mediates in the syntheses of lignin‐related phenyl­coumarans

Compounds (2R*,3S*)‐1‐(3,4‐dimethoxy­phen­yl)‐3‐{3‐meth­oxy‐2‐[(2R*)‐tetra­hydro­pyran‐2‐yl­oxy]phen­yl}‐2,3‐ep­oxy‐1‐propanone, C₂₃H₂₆O₇, (I), and trans‐1‐(3,4‐dimethoxy­phen­yl)‐3‐[3‐meth­oxy‐2‐(methoxy­methoxy)­phen­yl]‐2,3‐ep­oxy‐1‐propanone, C₂₀H₂₂O₇, (II), were obtained on epoxidation of chalcones. The stereochemistries of (I) and (II) were elucidated. In both compounds, the substituents on the oxirane ring are trans‐oriented. Compound (I) was obtained together with a diastereometric form that differs from (I) with respect to the configuration of the asymmetric C atom in the tetra­hydro­pyran group. The geometries of the substituted oxirane rings of (I) and (II) are very similar. The hydrogen‐bonding patterns, mediated via weak C—H⋯O inter­actions, differ considerably. The crystal structures of (I) and (II) are compared with those of related chalcone epoxides. The conversion of (I) and (II) into lignin‐related phenyl­coumarans is discussed.     

Two N‐ortho‐nitro­benzene­sulfonyl α,α‐disubstituted amino acid adducts

The carboxy group of 2‐methyl‐N‐[(2‐nitrophenyl)sulfonyl]­alanine, C₁₀H₁₂N₂O₆S, forms centrosymmetric hydrogen‐bonded dimers with an O?O distance of 2.629 (2) Å and an intramolecular N—H?O(nitro) hydrogen bond N?O distance of 2.823 (2) Å. 1‐[(2‐Nitro­phenyl)­sulfonyl­amino]­cyclo­hexane­carboxyl­ic acid, C₁₃H₁₆N₂O₆S, has Z′ = 2 and forms similar interactions.     

3,6,9,16,19,22‐Hexa­aza­tri­cyclo[22.2.­2.211,14]­tria­conta‐11,13,24,26(1),27,29‐hexa­ene penta­hydrate

In the title macrocyclic poly­amine, C₂₄H₃₈N₆·5H₂O, the centrosymmetric poly­amine mol­ecules are stacked in rows, and between these mol­ecules there are channels along the a axis. The intermolecular hydrogen bonds formed between the water and poly­amine, together with those formed between water mol­ecules, generate an extensive hydrogen‐bonding network.     

Two carbamoyl‐substituted di­hydro­pyrimidines: potential mimics of di­hydro­pyridine calcium channel blockers

The structures of two conformationally similar 1,4‐di­hydro­pyrimidines with a novel carbamoyl substitution, viz. 6‐methyl‐5‐(N‐methyl­carbamoyl)‐4‐phenyl‐1,2,3,4‐tetrahydro­py­rimidine‐2‐thione monohydrate, C₁₃H₁₅N₃OS·H₂O, (I), and 4‐(4‐chloro­phenyl)‐6‐methyl‐5‐(N‐methyl­carbamoyl)‐1,2,3,4‐tetra­hydro­pyrimidine‐2‐thione monohydrate, C₁₃H₁₄ClN₃OS·H₂O, (II), exhibit the structural features of 1,4‐di­hydro­pyridine calcium channel blockers. In both structures, the pyrimidine ring adopts a flattened boat conformation and the carbamoyl side chain is in an extended conformation with an anticlinal orientation. The phenyl ring occupies a pseudo‐axial position with respect to the pyrimidine ring in these structures. Both compounds crystallize with one mol­ecule of water, which participates in a two‐dimensional hydrogen‐bonding network. The mol­ecules are linked into dimers by N—H·S hydrogen bonds in both structures.     

Boc–Pro–Hyp–Gly–OBzl and Boc–Ala–Hyp–Gly–OBzl,two repeating triplets found in collagen

The protected tripeptides benzyl N‐{2‐[N‐(tert‐butoxy­carbon­yl)­prol­yl]‐4‐hydroxy­prol­yl}glycinate or Boc–Pro–Hyp–Gly–OBzl, C₂₄H₃₃N₃O₇, and benzyl N‐{2‐[N‐(tert‐butoxy­carbon­yl)­alan­yl]‐4‐hydroxy­prol­yl}glycinate or Boc–Ala–Hyp–Gly–OBzl, C₂₂H₃₁N₃O₇, are the minimum repeating triplets found in collagen. Within the crystal structure of each are two independent peptide mol­ecules with similar structures. The peptides are arranged anti­parallel to one another and inter­act through hydrogen bonds involving the main chains and the 4‐hydroxy­prolyl groups. The structures exhibit characteristics of a triple helix, but the peptides tend to assume a sheet‐like structure.