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The title compound, 3‐[(benzo‐1,3‐dioxol‐5‐yl)amino]‐4‐methoxycyclobut‐3‐ene‐1,2‐dione, C12H9NO5 (3), is a precursor to an antimycobacterial squaramide. Block‐shaped crystals of a monoclinic form (3‐I, space group P21/c, Z = 8, Z′ = 2) and needle‐shaped crystals of a triclinic form (3‐II, space group P‐1, Z = 4, Z′ = 2) were found to crystallize concomitantly. In both crystal forms, R22(10) dimers assemble through N—H...O=C hydrogen bonds. These dimers are formed from crystallographically unique molecules in 3‐I, but exhibit crystallographic Ci symmetry in 3‐II. Twinning by pseudomerohedry was encountered in the crystals of 3‐II. The conformations of 3 in the solid forms 3‐I and 3‐II are different from one another but are similar for the unique molecules in each polymorph. Density functional theory (DFT) calculations on the free molecule of 3 indicate that a nearly planar conformation is preferred. [ABSTRACT FROM AUTHOR]

1,3‐Benzothiazin‐4‐ones (BTZs) are a promising new class of drugs with activity against Mycobacterium tuberculosis, which have already reached clinical trials. A product obtained in low yield upon treatment of 8‐nitro‐2‐(piperidin‐1‐yl)‐6‐(trifluoromethyl)‐4H‐benzothiazin‐4‐one with 3‐chloroperbenzoic acid, in analogy to a literature report describing the formation of sulfoxide and sulfone derived from BTZ043 [Tiwari et al. (2015). ACS Med. Chem. Lett.6, 128–133], is a ring‐contracted benzisothiazolinone (BIT) 1‐oxide, namely, 7‐nitro‐2‐(piperidine‐1‐carbonyl)‐5‐(trifluoromethyl)benzo[d]isothiazol‐3(2H)‐one 1‐oxide, C14H12F3N3O5S, as revealed by X‐ray crystallography. Single‐crystal X‐ray analysis of the oxidation product originally assigned as BTZ043 sulfone provides clear evidence that the structure of the purported BTZ043 sulfone is likewise the corresponding BIT 1‐oxide, namely, 2‐[(S)‐2‐methyl‐1,4‐dioxa‐8‐azaspiro[4.5]decane‐8‐carbonyl]‐7‐nitro‐5‐(trifluoromethyl)benzo[d]isothiazol‐3(2H)‐one 1‐oxide, C17H16F3N3O7S. A possible mechanism for the ring contraction affording the BIT 1‐oxides instead of the anticipated constitutionally isomeric BTZ sulfones and antimycobacterial activities thereof are discussed. [ABSTRACT FROM AUTHOR]

Porphyrin assemblies display interesting photophysical properties and a relatively high thermal stability. Moreover, meso-functionalized porphyrins with virtually fourfold symmetry can be relatively readily synthesized from pyrrole and the appropriate aldehyde. A number of metallo derivatives of 5,10,15,20-tetrakis(4-cyanophenyl)porphyrin, where the N atom of the linear cyano group can act both as a donor for coordination bonds or as an acceptor for hydrogen bonds, have been structurally characterized by single-crystal X-ray analysis. The supramolecular and structural chemistry of the corresponding 2- and 3-cyanophenyl isomers of the parent porphyrin, however, has remained largely unexplored. The crystal structure of [5,10,15,20-tetrakis(3-cyanophenyl)porphyrinato]copper(II) (CuTCNPP) nitrobenzene trisolvate, [Cu(C48H24N8)]·3C6H5NO2, has been determined at 80 K by synchrotron single-crystal X-ray diffraction. CuTCNPP exhibits a C2 h-symmetric ααββ conformation, despite an unsymmetrical crystal environment, and is situated on a crystallographic centre of symmetry. The CuII ion adopts a genuine square-planar coordination by the four pyrrole N atoms. The 24-membered porphyrin ring system shows no marked deviation from planarity. In the crystal, the CuTCNPP molecules and two nitrobenzene molecules are face-to-face stacked in an alternating fashion, resulting in corrugated layers. The remaining nitrobenzene guest molecule per CuTCNPP resides in the region between four neighbouring columnar stacks of CuTCNPP and sandwiched nitrobenzene molecules, and is disordered over four positions about a centre of symmetry. [ABSTRACT FROM AUTHOR]

Acetic anhydride (ethanoic anhydride), (CH3CO)2O, is a widely used acetylation reagent in organic synthesis. The crystal and molecular structure, as determined by single-crystal X-ray analysis at 100 K, is reported for the first time. A crystal of the title compound (m.p. 200 K) suitable for X-ray diffraction was grown from the melt at low temperature. The title compound crystallizes in the orthorhombic space group Pbcn, with Z = 4. In the crystal, the molecule adopts an exact C2-symmetric conformation about a crystallographic twofold axis. The molecules are densely packed. Two of the methyl H atoms form short intermolecular contacts to a neighbouring carbonyl O atom, which can be viewed as weak hydrogen bonds. [ABSTRACT FROM AUTHOR]

Adiponitrile, C6H8N2, is a key intermediate in the synthesis of the polyamide Nylon 66 and is produced industrially on a large scale. We have determined the crystal and molecular structure of adiponitrile by single-crystal X-ray analysis at 100 K, a suitable crystal (m.p. 275 K) having been grown from the melt at low temperature. The compound crystallizes in the monoclinic space group P21/ c with Z = 2. In the crystal structure, the molecule adopts an exact Ci-symmetric gauche- anti- gauche conformation of the C-C-C-C skeleton about an inversion centre. The molecules are densely packed, with short intermolecular contacts between the α-H and nitrile N atoms. [ABSTRACT FROM AUTHOR]

The simplest alkyl aryl ether, anisole (methoxybenzene), C7H8O, is a feedstock chemical and is widely used in the pharmaceutical industry. The structure of anisole at 100 K, as determined by single-crystal X-ray analysis, is reported. A crystal (m.p. 236 K) suitable for X-ray diffraction was obtained from the melt. The title compound crystallizes in the centrosymmetric space group P21/ c with two molecules in the asymmetric unit ( Z′ = 2). Both crystallographically distinct molecules adopt a virtually flat ( Cs-symmetric) conformation. The arrangement of the molecules in the solid state appears to be governed by close packing. No face-to-face π-π stacking of the molecules is observed, but rather edge-to-face interactions result in a herringbone packing motif. [ABSTRACT FROM AUTHOR]