A dimeric layered structure of a 4‐oxo‐4,5‐di­hydro‐1H‐pyrazolo­[3,4‐d]­pyrimidine compound

The title compound, 6‐methyl­sulfanyl‐1‐(3‐phenyl­propyl)‐4,5‐di­hydro‐1H‐pyrazolo­[3,4‐d]­pyrimidin‐4‐one, C₁₅H₁₆N₄OS, crystallizes in space group Pbca, with two mol­ecules of similar structure in the asymmetric unit. The molecular structure shows the absence of intramolecular stacking in the crystalline state, as indicated by earlier ¹H NMR analysis in solution. In addition, the crystal packing reveals the formation of a layered structure, due mainly to intermolecular N—H?O=C hydrogen bonding and arene–arene interactions.     

4‐Chloro­aceto­phenone [1‐(4‐methoxyphenyl)­ethyl­idene]­hydra­zone

The crystal structure of the title mixed azine, C₁₇H₁₇ClN₂O, contains four independent mol­ecules, A–D, and mol­ecule B is disordered. All four mol­ecules have an N—N gauche conformation, with C—N—N—C torsion angles of 136.5 (4), 137.0 (4), ?134.7 (4) and ?134.7 (4)°, respectively. The phenyl rings are also somewhat twisted with respect to the plane defined by C_ipso and the imine bond. On average, the combined effect of these twists results in an angle of 64.7° between the best planes of the two phenyl rings. Arene–arene double T‐contacts are the dominant intermolecular inter­action. The methoxy‐substituted phenyl ring of one azine mol­ecule interacts to form a T‐contact with the methoxy‐substituted phenyl ring of an adjacent mol­ecule and, similarly, two chloro‐substituted phenyl rings of neighboring mol­ecules interact to form another T‐contact. The only exception is for mol­ecule B, for which the disorder leads to the formation of T‐­contacts between methoxy‐ and chloro‐substituted phenyl rings. The prevailing structural motif of T‐contact formation between like‐substituted arene rings results in a highly dipole‐parallel‐aligned crystal structure.     

Cone and 1,3‐alternate conformers of 1,3‐bis­(ethoxy­carbonyl­methoxy)‐2,4‐di­hydroxy­calix­[4]­arene and 1,2,3,4‐tetrakis­(ethoxy­carbonyl­methoxy)­calix­[4]­arene

The two title ethoxy­carbonyl­methoxy derivatives of calix­[4]­arene, namely diethyl 2,4‐di­hydroxy­calix­[4]­arene‐1,3‐diyldi(oxy­ace­tate), C₃₆H₃₆O₈, (I), and tetraethyl ­calix­[4]­arene‐1,2,3,4‐tetra­yltetra­(oxy­acetate), C₄₄H₄₈O₁₂, (II), form two different conformations, viz. a cone in (I), where intramol­ecular hydrogen bonds are formed through OH groups in a partially substituted calix­[4]­arene, and a 1,3‐alternate form of a completely substituted calix­[4]­arene in (II). A unique three‐dimensional array of mol­ecules exists in (II), with the channels extended along the entire crystal.     

5,11,17,23‐Tetra‐tert‐butyl‐25,26,27,28‐tetrakis(2‐cyano­benzyl­oxy)‐2,8,14,20‐tetra­thia­calix­[4]­arene–di­chloro­methane (1/2)

A new p‐tert‐butyl­thia­calix­[4]­arene derivative, C₇₂H₆₈N₄O₄S₄·2CH₂Cl₂, has been synthesized and is comprised of one tetra‐p‐tert‐butyltetrakis(2‐cyano­benzyl­oxy)­tetra­thia­calix­[4]arene and two di­chloro­methane mol­ecules. The calix­[4]­arene mol­ecule is centrosymmetric and adopts an unusual 1,2‐alternate conformation viaπ–π interactions between adjacent cyano­phenyl rings on the lower rim of the parent thia­calix­[4]­arene system.     

2‐(Acridin‐9‐yl­imino)‐3‐di­methyl­amino‐1,3‐thia­zolidin‐4‐one

In the title compound, C₁₈H₁₆N₄OS, prepared by the reaction of 4‐(acridin‐9‐yl)‐1,1‐di­methyl­thio­semicarbazide with methyl bromo­acetate, the acridine and thia­zolidine ring systems are both non‐planar and, because of steric requirements, almost perpendicular, with a dihedral angle between their planes of 99.69 (6)°. C—H·O and C—H·π(arene) hydrogen bonds stabilize the crystal structure in the solid state.     

A hydrogen‐bonded heterodimer of 1‐(4‐hexyloxyphenyl)pyridin‐4(1H)‐one with 4‐cyano­benzoic acid

The two components of the title heterodimer, C₁₇H₂₁NO₂·C₈H₅NO₂, are linked end‐to‐end via O—H⋯O(=C) and C—H⋯O(=C) hydrogen‐bond inter­actions. Additional lateral C—H⋯O inter­actions link the dimers in a side‐by‐side fashion to produce wide infinite mol­ecular ribbons. Adjacent ribbons are inter­connected viaπ–π stacking and C—H⋯π(arene) inter­actions. This structure represents the first evidence of robust hydrogen‐bond formation between the moieties of pyridin‐4(1H)‐one and benzoic acid.     

2‐Iodo‐N‐(3‐nitrobenzyl)aniline and 3‐iodo‐N‐(3‐nitrobenzyl)aniline exhibit entirely different patterns of supramolecular aggregation

In 2‐iodo‐N‐(3‐nitro­benzyl)­aniline, C₁₃H₁₁IN₂O₂, the mol­ecules are linked into a three‐dimensional structure by a combination of C—H?O hydrogen bonds, iodo–nitro interactions and aromatic π–π‐stacking interactions, but N—H?O and C—H?π(arene) hydrogen bonds are absent. In the isomeric 3‐iodo‐N‐(3‐nitro­benzyl)­aniline, a two‐dimensional array is generated by a combination of N—H?O, C—H?O and C—H?π(arene) hydrogen bonds, but iodo–nitro interactions and aromatic π–π‐stacking interactions are both absent.     

25,27‐(6‐Tosyl‐3,9‐dioxa‐6‐aza­un­decane‐1,11‐diyldioxy)‐26,28‐(3,6,9‐trioxaun­decane‐1,11‐diyldioxy)­calix­[4]­arene

A new calix­[4]‐­crowned aza­crown ether, C₅₁H₅₉NO₁₁S, consisting of four phenyl rings in a 1,3‐alternate conformation was synthesized from the reaction of 25,27‐bis(5‐chloro‐3‐oxa­pentyl­oxy)­calix­[4]­crown‐5 and p‐toluene­sulfon­amide in the presence of Cs₂CO₃. A crown‐5 loop was attached on the two facing lower rims of the calix­[4]­arene and the N‐tosyl aza­crown group was attached on the other set of lower rims of the calix­[4]­arene backbone. This mol­ecule seems to offer an inside cavity for the formation of a host–guest complex.     

5‐Fluoro‐1‐octanoyl­uracil

The crystal structure of 5‐fluoro‐1‐octanoyl­uracil [5‐fluoro‐1‐octanoyl­pyrimidine‐2,4(1H,3H)‐dione, C₁₂H₁₇FN₂O₃], a lipophilic prodrug of 5‐fluoro­uracil, is described. The 5‐fluoro­pyrimidine‐2,4(1H,3H)‐dione moiety is similar to the known structure of 1‐acetyl‐5‐fluoro­uracil. The 1‐octanoyl group and the 5‐fluoro­uracil moiety are essentially coplanar, with the octanoyl carbonyl group oriented towards the the ring C—H group and away from the nearer ring carbonyl group. The torsion angle C—N—C—O (from the ring CH group to the octanoyl carbonyl group) of 9.2 (2)° is similar to the corresponding torsion angles reported for 1‐acetyl‐5‐fluoro­uracil (17.3 and 1.6°) and 1,3‐di­acetyl‐5‐fluoro­uracil (8.8°).     

Four (E,Z,E)‐1‐(4‐alkoxy­phen­yl)‐6‐(4‐nitro­phen­yl)hexa‐1,3,5‐trienes

The crystal structures of the four E,Z,E isomers of 1‐(4‐alk­oxy­phen­yl)‐6‐(4‐nitro­phen­yl)hexa‐1,3,5‐triene, namely (E,Z,E)‐1‐(4‐methoxy­phen­yl)‐6‐(4‐nitro­phen­yl)hexa‐1,3,5‐triene, C₁₉H₁₇NO₃, (E,Z,E)‐1‐(4‐ethoxy­phen­yl)‐6‐(4‐nitro­phen­yl)hexa‐1,3,5‐triene, C₂₀H₁₉NO₃, (E,Z,E)‐1‐(4‐nitro­phen­yl)‐6‐(4‐n‐propoxyphen­yl)hexa‐1,3,5‐triene, C₂₁H₂₁NO₃, and (E,Z,E)‐1‐(4‐n‐butoxy­phen­yl)‐6‐(4‐nitro­phen­yl)hexa‐1,3,5‐triene, C₂₂H₂₃NO₃, have been determined. Inter­molecular N⋯O dipole inter­actions between the nitro groups are observed for the meth­oxy derivative, while for the eth­oxy derivative, two adjacent mol­ecules are linked at both ends through N⋯O dipole–dipole inter­actions between the N atom of the nitro group and the O atom of the eth­oxy group to form a supra­molecular ring‐like structure. In the crystal structures of the n‐prop­oxy and n‐but­oxy derivatives, the shortest inter­molecular distances are those between the two O atoms of the alk­oxy groups. Thus, the nearest two mol­ecules form an S‐shaped supra­molecular dimer in these crystal structures.     

Thermal isomerization pathway of 1‐(4‐nitrophenyl)‐2‐phenyl­imino‐2,5‐di­hydro‐1H‐pyrido­[3,2‐b]­indole‐3‐carbo­nitrile discovered by laboratory powder data

The evidence for thermal isomerization of the title compound, C₂₄H₁₅N₅O₂, into 2‐[(4‐nitro­phenyl)­phenyl­amino]‐5H‐pyrido[3,2‐b]­indole‐3‐carbo­nitrile has been obtained as a consequence of crystal structure determinations from laboratory powder data.     

1H‐Imidazol‐1‐yl 1,2,3,4‐tetra­hydro­isoquinolin‐2‐yl ketone

In the crystal structure of the title compound, C₁₃H₁₃N₃O, the C—N_imidazole bond length of 1.431 (3) Å is shorter than that observed [1.466 (6) Å] in the corresponding carbamoyl­imidazolium salt 3‐methyl‐1‐(1,2,3,4‐tetra­hydro­isoquinolin‐2‐yl­carbonyl)­imidazolium iodide. A comparision of these compounds is used to highlight the structural differences that occur as a result of the imidazolium effect. Weak C—H⋯O hydrogen bonds link mol­ecules into extended tapes in the a direction.     

N‐(4‐Cyano­phenyl)‐α‐(4‐methoxy­phenyl)­nitro­ne

In the crystal structure of the title compound, 4‐cyano‐N‐(4‐methoxy­benzyl­idene)­phenyl­amine N‐oxide, C₁₅H₁₂N₂O₂, the 4‐methoxy­phenyl is approximately coplanar with the nitrone moiety but significantly rotated with respect to the 4‐cyano­phenyl moiety. The extent of this rotation is significantly different for the two crystallographically independent mol­ecules of the asymmetric unit [dihedral angles of 19.4 (1) and 26.5 (1)°]. The geometry about the C=N bond is Z. The two mol­ecules are related to one another by a pseudo inversion centre.     

1‐(1‐Benzoylpropen‐2‐yl)‐3‐methylisothiosemicarbazide

The structure of the title S‐alkyl­ated iso­thio­semicarbazide, C₁₂H₁₅N₃OS, was determined by single‐crystal diffractometry and compared with the structures of other compounds containing the S‐alkyl­thio­semicarbazide moiety. Such structures cluster into two groups, according to the different orientation of the –SR group with respect to the hydrazine N atom of the thio­semicarbazide. The cis arrangement is preferred by most mol­ecules in the solid state, in spite of the possibility of intramolecular N—H?N interactions in the opposite orientation.     

A 1,3,2‐ox­aza­borolidine dimer derived from (S)‐α,α‐di­phenyl­prolinol

The reaction of (S)‐α,α‐di­phenyl­prolinol with an excess of borane–tetra­hydro­furan complex yields a stable crystalline material with the composition C₃₄H₃₈B₂N₂O₂, which features a borane adduct of a spiro­cyclic structure with two ox­aza­borolidine rings joined by a central tetrahedral B atom. This dimeric ox­aza­borolidine complex, viz. 3,3,3′,3′‐tetra­phenyl‐1,1′‐spiro­bi(3a,4,5,6‐tetra­hydro‐3H‐pyrrolo­[1,2‐c][1,3,2]­ox­azaborole)–7‐borane, is the dominant product under various reaction conditions; its crystal structure is consistent with ¹¹B, ¹H and ¹³C NMR and IR analyses.     

Potassium 3‐cyano‐4‐(dicyanomethylene)‐5‐oxo‐4,5‐dihydro‐1H‐pyrrol‐2‐olate

The crystal structure of the title potassium salt, K⁺·C₈HN₄O₂⁻, of the organic anion 3‐cyano‐4‐(di­cyano­methyl­ene)‐5‐oxo‐4,5‐di­hydro‐1H‐pyrrol‐2‐olate shows that the di­cyano­methyl­ene moiety is able to accept an electron in the same way as does tetra­cyano­ethyl­ene, to yield the novel product. The organic anion is nearly planar, with deviations caused by steric crowding among the exocyclic cyano groups. The K⁺ cations lie within tricapped trigonal prisms that stack to form channels. The three‐dimensional structure is completed by the formation of hydrogen‐bonded chains by the anions.     

(η6‐Hexamethylbenzene)(mesidine)­ditriflatoruthenium(II)

The crystal structure of the title complex, (η⁶‐hexamethylbenzene)bis(trifluoromethanesulfonato‐O)(2,4,6‐trimethylanil­ine‐N)ruthenium(II), [Ru(CF₃O₃S)₂(C₁₂H₁₈)(C₉H₁₃N)], is described. The complex has the classic three‐legged piano‐stool structure with a planar arene 1.667 Å from the metal, two monodentate O‐bound tri­fluoro­methane­sulfonate ligands [Ru—O 2.169 (2) and 2.174 (2) Å] and one N‐bound mesidine ligand [Ru—N 2.198 (2) Å]. The Ru—N distance is relatively long and the average Ru—O distance is relatively short when compared with previously characterized Ru^II complexes.     

2,2‐Di­methyl‐1‐(2,4,6‐tri­nitro­phenyl)­hydrazine

The title mol­ecule (DMPH‐H), C₈H₉N₅O₆, was investigated to provide comparison with 2,2‐di­phenyl‐1‐picryl­hydrazine, which unlike DMPH‐H is readily oxidizable to form a well known stable free radical (DPPH). The structure shows essential differences in the configuration of the hydrazine‐N atoms, the ortho‐nitro group orientations and the crystal packing. The bond angles of the di­methyl­amino N atom [107.90 (13), 108.96 (12) and 112.21 (13)°] are consistent with a tetrahedral N atom and sp³ hybridization.     

From α‐carbamoyl‐α‐cyano­oxiranes to 3‐halogenopyruv­amides

The crystal structures of the first stable α‐diol from the α‐halogenopyruv­amide series, 3‐chloro‐2,2‐di­hydroxy‐3‐phenyl­propan­amide, C₉H₁₀­ClNO₃, and three products [3‐(4‐chloro­phenyl)‐2‐cyano‐2,3‐epoxy­propan­amide, C₁₀H₇­ClN₂O₂, 3‐bromo‐2‐cyano‐2‐hydroxy‐3‐p‐tolyl­propan­amide, C₁₁H₁₁Br­N₂O₂, 3‐bromo‐2‐oxo‐3‐p‐tolyl­propan­amide, C₁₀H₁₀­BrNO₂] obtained during the systematic synthesis of α‐halogenopyruv­amides are reported. The crystal structures are dominated by hydrogen bonds involving an amide group. The stability of the geminal diol could be ascribed to hydrogen bonds which involve both hydroxyl groups.     

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.