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Propane-1,3-diaminium squarate dihydrate, C3H12N22+·C4O42−·2H2O, results from the proton-transfer reaction of propane-1,3-di amine with squaric acid and subsequent crystallization from aqueous medium. The title compound crystallizes in the tetragonal crystal system (space group P4bm) with Z = 2. The squarate dianion belongs to the point group D4h and contains a crystallographic fourfold axis. The propane-1,3-diaminium dication exhibits a C2v-symmetric all-anti conformation and resides on a special position with mm2 site symmetry. The orientation of the propane-1,3-diaminium ions makes the crystal structure polar in the c-axis direction. The solid-state supramolecular structure features a triperiodic network of strong hydrogen bonds of the N—H⋯O and O—H⋯O types. [ABSTRACT FROM AUTHOR]

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]

Reaction of 4,6-dinitroresorcinol (1) and the nitrogen base 1,4-diazabicyclo[2·2·2]octane (2) affords the 1:2 salt and proton-transfer compound 1,4-diazabicyclo[2·2·2]octane-1,4-diium bis(5-hydroxy-2,4-dinitrophenolate) (3). Compound 3 crystallizes in the triclinic crystal system (space group P-1) with a = 8.3242(5) Å, b = 11.9915(7) Å, c = 12.4595(7) Å, α = 116.282(2)°, β = 100.576(3)°, γ = 101.051(2)°, 1042.30(11) Å3 and Z = 2. The dication 2- H 2 2 + forms charge assisted donating bifurcated N+−H⋅⋅⋅O− hydrogen bonds to the phenolate moieties of two monoanions of 1. The latter exhibit an intramolecular O−H⋅⋅⋅O hydrogen bond between the hydroxy group and the nitro group in ortho position. The crystal structure of 3 features pseudo B-centering of the lattice, which relates the two crystallographically distinct monoanions of 1 by a pseudo translation. The possible B-centring is broken by the ethylene groups of 2-H22+, which are related in neighbouring molecules by centres of symmetry. [ABSTRACT FROM AUTHOR]

4-(4-nitrophenyl)thiomorpholine, the title compound, has been used as a precursor for the corresponding 4-thiomorpholinoaniline, which is a useful building block in medicinal chemistry. The crystal and molecular structures of the title compound, however, have not been described thus far. We synthesized the title compound by means of a nucleophilic aromatic substitution reaction of 4-fluoronitrobenzene and thiomorpholine and structurally characterized it by X-ray crystallography, DFT calculations, and Hirshfeld surface analysis. In the crystal, the molecule exhibits an approximately CS-symmetric structure, with the nitrogen-bound 4-nitrophenyl group in a quasi axial position on the six-membered thiomorpholine ring in a low-energy chair conformation. The solid-state structure of the title compound is markedly different from that of its morpholine analogue. This can be ascribed to the formation of centrosymmetric dimers through intermolecular C–H···O weak hydrogen bonds involving the methylene groups adjacent to the sulfur atom and face-to-face aromatic stacking. [ABSTRACT FROM AUTHOR]

Betaines of squaric acid have gained research interest because of their structural and spectral properties. We elucidated the crystal and molecular structure of the triethylammonium betaine of squaric acid (1) by X-ray crystallography, IR, and NMR spectroscopy augmented by Hirshfeld surface analysis and DFT calculations. The crystal structure determination using Hirshfeld atom refinement reveals that the resonance hybrid structure with partial enolate character of the two lateral squaric acid C=O groups describes 1 best. The solid-state supramolecular structure features weak intermolecular C−H···O hydrogen bonds. The number of C=O bands in the IR spectrum in the solid-state is consistent with local C2v symmetry of the squaric acid residue in 1. The 13C NMR signals of this group in solution were assigned based on 2D NMR experiments and computational prediction using the Gauge-Independent Atom Orbital (GIAO) method. The present study provides the first structural characterization of a betaine of squaric acid containing a four-coordinate nitrogen atom directly attached to the four-membered ring. [ABSTRACT FROM AUTHOR]

Trehalose conjugates of 3-hydroxychromone (3HC) dyes have previously been utilized as fluorescence labels to detect metabolically active mycobacteria with a view to facilitating point-of-care detection of mycobacterial pathogens, especially Mycobacterium tuberculosis. We subjected the 3HC dye 2-(6-(diethylamino)benzofuran-2-yl)-3-hydroxy-4H-chromen-4-one (3HC-2) to a combined X-ray crystallography and density functional theory (DFT) study, and conducted preliminary fluorescence labelling experiments with the model organism Mycobacterium aurum. In the crystal, 3HC-2 exhibits an s-cis conformation of the chromone and the benzofuran moieties about the central C–C bond. According to DFT calculations, the s-cis conformer is about 1.8 kcal mol−1 lower in energy than the s-trans conformer. The solid-state supramolecular structure features hydrogen-bonded dimers and π...π stacking. Fluorescence microscopy revealed fluorescence of M. aurum cells treated with the dye trehalose conjugate 3HC-2-Tre in the GFP channel. It was concluded that s-cis is the preferred conformation of 3HC-2 and that the generally considered non-pathogenic M. aurum can be labelled with the fluorescence probe 3HC-2-Tre for convenient in vitro drug screening of new antimycobacterial agents. [ABSTRACT FROM AUTHOR]

Tuberculosis is the leading bacterial killer worldwide. 8-Nitro-4H-benzo[e][1,3]thiazin-4-ones are a potent class of antitubercular agents with a new mechanism of action. BTZ043 and PBTZ169 (macozinone) have progressed to clinical studies. Herein, we give a comprehensive account of this important class of potential new drugs to treat tuberculosis. We present an overview of recent developments in the field of antitubercular benzothiazinones (BTZs) and summarize our own contributions. The review covers synthesis, structures and reactivity, mechanism of action, in vitro activity and structure activity relationships (SARs), physicochemical and pharmacokinetic properties as well as a brief summary of in vivo models and clinical studies. We address bioavailability issues and the challenge of the potentially toxic nitroaromatic moiety, including reactivity towards nucleophiles in vivo and highlight possible directions of further research into BTZs through chemical modification. [ABSTRACT FROM AUTHOR]

Two bismuth(III) coordination polymers, namely [Bi2X6(µ-dtpo)3]n [X = Cl (1), Br (2); dtpo = 2,2′-dithiobis(pyridine N-oxide)], were prepared using a crystal engineering strategy and structurally characterized by X-ray crystallography. In the isostructural compounds 1 and 2 (trigonal system, space group P-3c1), fac-configured BiX3 units as nodes are joined by the C2-symmetrical dtpo bridging ligand as spacers to generate 2D honeycomb layers with (6,3) topology. The 2D sheets stack along the [001] direction, resulting in virtually hexagonal channels parallel to this direction, which are occupied by disordered methanol and water molecules. The potential solvent area per unit cell volume is 42.2% for 1 and 44.0% for 2. Two isostructural 2D honeycomb bismuth(III) coordination, synthesized from 2,2′-dithiobis(pyridine N-oxide) and bismuth(III) halides are described. [ABSTRACT FROM AUTHOR]

(Z)-1,2-Bis[4-oxo-2-(piperidin-1-yl)-6-(trifluoromethyl)-4H-benzo[e][1,3]thiazin-8-yl]diazene oxide, C28H24F6N6O3S2, was obtained and its structure determined while attempting to crystallize and structurally characterize 8-nitro-2-(piperidin-1-yl)-6-(trifluoromethyl)-4H-benzo[e][1,3]thiazin-4-one, a simplified analogue of the antituberculosis clinical drug candidate BTZ043. X-ray crystallography revealed the structure of the azoxy compound to be comprised of two benzothiazinone moieties linked by a Z-configured azoxy group in an almost coplanar arrangement. In the crystal, the molecules are densely packed, revealing a herringbone pattern. [ABSTRACT FROM AUTHOR]

The crystal structure and in vitro antimycobacterial properties of N-(2-fluoroethyl)-1-[(6-methoxy-5-methylpyrimidin-4-yl)methyl]-1H-benzo[d]imidazole-4-carboxamide (C17H18FN5O2, 1), a previously reported benzimidazoleanalogue of the 1,4-azaindole-based antituberculosis drug candidate TBA-7371, are reported. The structure determination was achieved using Hirshfeld atomrefinement. Compound 1 crystallizes in the triclinic system (space group P1)with two molecules in the asymmetric unit (Z0 = 2). The two crystallographicallydistinct molecules exhibit a similar conformation with the amide groups in a Zconformation, forming an intramolecular Namide--H· · ·Nbenzimidazole hydrogenbond. The most significant supramolecular feature in the solid-state is arelatively short Cbenzimidazole--H· · ·Npyrimidine hydrogen bond. Antimycobacterialtesting confirmed in vitro activity against Mycobacterium smegmatis, but nogrowth inhibtion of Mycobacterium abscessus was found. [ABSTRACT FROM AUTHOR]

Synthesis and structural characterization of two heterodinuclear ZnII-LnIII complexes with the formula [ZnLn(HL)(µ-OAc)(NO3)2(H2O)x(MeOH)1-x]NO3 · n H2O · n MeOH [Ln = Pr (1), Nd (2)] and the crystal and molecular structure of [ZnNd(HL)(µ-OAc)(NO3)2(H2O)] [ZnNd(HL)(OAc)(NO3)2(H2O)](NO3)2 · n H2O · n MeOH (3) are reported. The asymmetrical compartmental ligand (E)-2-(1-(2-((2-hydroxy-3-methoxybenzylidene)amino)-ethyl)imidazolidin-2-yl)-6-methoxyphenol (H2L) is formed from N1,N3-bis(3-methoxysalicylidene)diethylenetriamine (H2valdien) through intramolecular aminal formation, resulting in a peripheral imidazoline ring. The structures of 1–3 were revealed by X-ray crystallography. The smaller ZnII ion occupies the inner N2O2 compartment of the ligand, whereas the larger and more oxophilic LnIII ions are found in the outer O2O2' site. Synthesis and structural characterization of two heterodinuclear ZnII-LnIII complexes (Ln = Pr, Nd) bearing an asymmetrical compartmental ligand formed in situ from N1,N3-bis(3-methoxysalicylidene)diethylenetriamine (H2valdien) through intramolecular aminal formation are reported. [ABSTRACT FROM AUTHOR]

Reactions of 2,2'-dithiobis(pyridine N-oxide) with various ZnII metal precursors and HgII halides are investigated and the products structurally characterized by X-ray crystallography. The crystal structures of the heteroleptic dinuclear complexes [HgX2(pyrithionate)2] (X = Br, I) are reported for the first time and that of the widely used antifungal and antifouling agent, the homoleptic dinuclear complex [Zn2(pyrithionate)4] (zinc pyrithione), is redetermined at low temperature, thereby improving the previous room temperature study in terms of precision. The encountered anionic chelate ligand pyrithionate results from reductive cleavage of the disulfide bond of 2,2'-dithiobis(pyridine N-oxide). [ABSTRACT FROM AUTHOR]

Two polymorphic forms of 1-(4-methylpyridin-2-yl)thiourea (1) and the crystal and molecular structures of the 2-aminothiazoles N-(4-methylpyridin-2-yl)-4-(pyridin-2-yl)thiazol-2-amine (2) and N-(4-methylpyridin-2-yl)-4-(pyrazin-2-yl)thiazol-2-amine (3), derived from 1 and the respective α-bromoketone via the Hantzsch reaction, are described. Both polymorphic forms 1α (space group P21/c, Z = 4) and 1β (space group P21/n, Z = 8) crystallize in the monoclinic system but exhibit distinctly different intermolecular hydrogen bonding patterns. Compound 2 (orthorhombic, space group Pca21, Z = 8) forms polymeric N–H⋯N hydrogen-bonded zigzag tapes in the polar crystal structure, with a significant twisting between the thiazole and pyridine rings. In contrast, the crystal structure of 3 (monoclinic, space group P21/c, Z = 4) features nearly planar centrosymmetric N–H⋯N hydrogen-bonded dimers, which are laterally joined through long C–H⋯N contacts, affording a π⋯π stacked layered structure. Two polymorphs of 1-(4-methylpyridin-2-yl)thiourea and the crystal and molecular structures of two 2-aminothiazoles, derived from 1-(4-methylpyridin-2-yl)thiourea and α-bromoketones via Hantzsch reaction, are reported. [ABSTRACT FROM AUTHOR]

Nα-2-thiophenoyl-d-phenylalanine-2-morpholinoanilide (MMV688845, IUPAC: N-(1-((2-morpholinophenyl)amino)-1-oxo-3-phenylpropan-2-yl)thiophene-2-carboxamide) from the Pathogen Box® library (Medicines for Malaria Ventures, MMV) is a promising lead compound for antimycobacterial drug development. Two straightforward synthetic routes to the title compound starting from phenylalanine or its Boc-protected derivative are reported. Employing Boc-phenylalanine as starting material and the T3P® and PyBOP® amide coupling reagents enables racemization-free synthesis, avoiding the need for subsequent separation of the enantiomers. The crystal structure of the racemic counterpart gives insight into the molecular structure and hydrogen bonding interactions in the solid state. The R-enantiomer of the title compound (derived from d-phenylalanine) exhibits activity against non-pathogenic and pathogenic mycobacterial strains, whereas the S-enantiomer is inactive. Neither of the enantiomers and the racemate of the title compound shows cytotoxicity against various mammalian cells. [ABSTRACT FROM AUTHOR]

8-Nitro-1,3-benzothiazin-4-ones (BTZs), with BTZ043 and PBTZ169 as the most advanced compounds, represent a new class of potent antitubercular agents, which irreversibly inhibit decaprenylphosphoryl-β-d-ribose-2′-epimerase (DprE1), an enzyme crucial for cell wall synthesis in the pathogen Mycobacterium tuberculosis. Synthesis, structural characterization and in vitro testing against Mycobacterium aurum DSM 43999 and M. tuberculosis H37Rv of halogenated 2-(4-ethoxycarbonylpiperazin-1-yl)-1,3-benzothiazin-4-ones lacking a nitro group are reported. X-ray crystallography reveals that the structure of the BTZ scaffold can significantly deviate from planarity. In contrast to recent reports, the results of the present study indicate that further investigation of halogenated non-nitro BTZs for antitubercular activity is less than a promising approach. [ABSTRACT FROM AUTHOR]

The synthesis and structural characterization of N-(6-methoxypyridin-3-yl)-4-(pyridin-2-yl)thiazol-2-amine mono-hydrobromide monohydrate (3) and N-(6-methoxypyridin-3-yl)-4-(pyrazin-2-yl)thiazol-2-amine mono-hydrobromide 0.35 methanol solvate (4) are reported. The crystal structures of 3 (monoclinic, space group P21/n, Z = 4) and 4 (monoclinic, space group, C2/c, Z = 8) feature N,4-diheteroaryl 2-aminothiazoles showing similar molecular conformations but different sites of protonation and thus distinctly different intermolecular hydrogen bonding patterns. In 3, Namine–H⋯Br−, N+pyridine–H⋯Owater, and Owater–H⋯Br− hydrogen bonds link protonated N-(6-methoxypyridin-3-yl)-4-(pyridin-2-yl)thiazol-2-amine and water molecules and bromide anions into a three-dimensional hydrogen-bonded network, whereas intermolecular N+methoxypyridine–H⋯Npyrazine hydrogen bonds result in hydrogen-bonded zigzag chains of protonated N-(6-methoxypyridin-3-yl)-4-(pyrazin-2-yl)thiazol-2-amine molecules in 4. [ABSTRACT FROM AUTHOR]

8-Nitro-1,3-benzothiazin-4-ones are a promising class of new antitubercular agents, two candidates of which, namely BTZ043 and PBTZ169 (INN: macozinone), have reached clinical trials. The crystal and molecular structures of two synthetic precursors, 2-chloro-3-nitro-5-(trifluoromethyl)benzoic acid, C8H3ClF3NO4 (1), and 2-chloro-3-nitro-5-(trifluoromethyl)benzamide, C8H4ClF3N2O3 (2), are reported. In 1 and 2, the respective carboxy, carboxamide and the nitro groups are significantly twisted out of the plane of the benzene ring. In 1, the nitro group is oriented almost perpendicular to the benzene ring plane. In the crystal, 1 and 2 form O-H...O and N-H...O hydrogen-bonded dimers, respectively, which in 2 extend into primary amide tapes along the [101] direction. The trifluoromethyl group in 2 exhibits rotational disorder with an occupancy ratio of 0.876 (3):0.124 (3). [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]

1,3-Benzo­thia­zin-4-ones (BTZs) are a promising new class of anti-tuberculosis drug candidates, some of which have reached clinical trials. The title compound, the benzamide derivative [2-chloro-3-nitro-5-(tri­fluoro­meth­yl)phen­yl](piper­id­in-1-yl)methanone, C13H12ClF3N2O3, occurs as a side product as a result of competitive reaction pathways in the nucleophilic attack during the synthesis of the BTZ 8-nitro-2-(piperidin-1-yl)-6-(tri­fluoro­meth­yl)-1,3-benzo­thia­zin-4-one, following the original synthetic route, whereby the corresponding benzoyl iso­thio­cyanate is reacted with piperidine as secondary amine. In the title compound, the nitro group and the nearly planar amide group are significantly twisted out of the plane of the benzene ring. The piperidine ring adopts a chair conformation. The tri­fluoro­methyl group exhibits slight rotational disorder with a refined ratio of occupancies of 0.972 (2):0.028 (2). There is structural evidence for inter­molecular weak C—HO hydrogen bonds. [ABSTRACT FROM AUTHOR]

The synthesis of ethyl 2-[(4-methyl­pyridin-2-yl)amino)-4-(pyridin-2-yl)thia­zole- 5-carboxyl­ate via the Hantzsch reaction and partial in situ transesterification during recrystallization from methanol-d4 to the d3-methyl ester, resulting in the title solid solution, ethyl 2-[(4-methyl­pyridin-2-yl)amino)-4-(pyridin-2-yl)thia­zole-5-carboxyl­ate–d3-methyl 2-[(4-methyl­pyridin-2-yl)amino)-4-(pyridin-2-yl)thia­zole-5-carboxyl­ate (0.88/0.12), 0.88C17H16N4O2S·0.12C16D3H11N4O2S, is reported. The refined ratio of ethyl to d3-methyl ester in the crystal is 0.880 (6):0.120 (6). The pyridine ring is significantly twisted out of the plane of the approximately planar picoline thia­zole ester moiety. N—H...N hydrogen bonds between the secondary amino group and the pyridine nitro­gen atom of an adjacent symmetry-related mol­ecule link the mol­ecules into polymeric hydrogen-bonded zigzag tapes extending by glide symmetry in the [001] direction. There is structural evidence for intra­molecular NS chalcogen bonding and inter­molecular weak C—H...O hydrogen bonds between adjacent zigzag tapes. [ABSTRACT FROM AUTHOR]

The crystal and molecular structures of the bio-based platform chemical furfural (1) and its derivatives furfurylamine (2), 2-furonitrile (3) and 2-methylfuran (4), which are all liquid at ambient temperature, have been determined by in situ cryocrystallography. Compound 1 crystallizes with three molecules in the asymmetric unit (Z′ = 3), which all adopt the syn conformation. Compound 2 crystallizes with two crystallographically distinct molecules in gauche and anti conformers, which are linked by N–H…N and N–H…O hydrogen bonds. The crystal structure of 3 is characterized by C–H…N interactions between C4 of the furan ring and the nitrile group. Compound 4 was found to crystallize in the non-centrosymmetric space group P42bc with a polar c axis. The molecular structures are compared with results from spectroscopic studies in the literature. Compounds 1–4 show a difference of ca. 14° between the external C–C–C and C–C–O angles to the substituent carbon atom in 2-position of the furan ring. Using this criterion as an indicator for the assignment of the oxygen atom in 2-substituted furan derivatives, a number of crystal structures in the Cambridge Structural Database (CSD) are called into question. [ABSTRACT FROM AUTHOR]

Abstract: The crystal and molecular structure of [Cu2(H2valdien)2](NO3)2 (1), whereby H2valdien is the known Schiff base ligand N1,N3-bis(3-methoxysalicylidene)diethylenetriamine, is reported. In 1, two H2valdien ligands join two CuII ions in a chelate-spacer-chelate mode, in which the protonated aliphatic secondary amine moieties represent the spacers, to form a double helix. Both CuII ions in the homodinuclear cationic complex exhibit similar distorted square-planar N2O2 coordination spheres. The axially chiral molecular structure of the [Cu2(H2valdien)2]2+ complex features intramolecular π···π stacking and N-H⋯O hydrogen bonds in the crystal. Compound 1 crystallizes in the Sohncke space group P21, with a = 14.165(3), b = 13.7755(13), c = 21.1185(4) Å, β = 102.199(4)°, and with two enantiomeric molecules in the asymmetric unit (Z′ = 2). The two crystallographically unique [Cu2(H2valdien)2]2+ enantiomers are related by pseudo inversion symmetry.Graphical Abstract: The pseudo centrosymmetric chiral Z′ = 2 crystal structure (space group P21) of [Cu2(H2valdien)2](NO3)2, whereby H2valdien is the known Schiff base ligand N1,N3-bis(3-methoxysalicylidene)diethylenetriamine, is reported. [ABSTRACT FROM AUTHOR]

The title compound, [HgI2(C10H8N2O2S2)]n, a one-dimensional coordination polymer with HgI2 units and 2,2′-di­thio­bis­(pyridine N-oxide) spacer ligands in an alternating fashion, forms helical chains running along the b axis in the crystal. Within a single coordination polymer strand, the axially chiral 2,2′-di­thio­bis­(pyridine N-oxide) ligands are homochiral, but the enanti­omeric conformation is present in adjacent strands. Within a coordination polymer strand, the iodido ligands point towards the centroids of the aromatic rings of the pyridine N-oxide moieties in the coordination sphere of HgII. Moreover, intra-strand C—HO and C—HI inter­actions, and inter-strand short SI and SO contacts are observed. [ABSTRACT FROM AUTHOR]

Group 12 halides and 2,2′-dithiobis(pyridine N-oxide) (dtpo) form the crystalline the 1D coordination polymers [Zn X2(μ-dtpo-κ2 O: O′)] n [ X = Cl ( 1), Br ( 2), I ( 3)], [Cd3(μ-Cl)4Cl2(μ-dtpo-κ2 O: O′)2(CH3OH)2] n ( 4), [(CdBr2)2(μ3-dtpo-κ3 O, O: O′)2(H2O)2] n ( 5), and [(CdI2)2(μ-dtpo-κ2 O: O′)3] n ( 6) in methanol. The compounds were structurally characterized by single-crystal X-ray analysis. Compounds 1- 3 represent an isomorphous series of single-stranded coordination polymers, whereas the CdII derivatives are structurally diverse. The metal nodes in 4 and 5 are trinuclear and dinuclear cadmium clusters, respectively. In 4 and 5, the metal nodes are linked into double-stranded 1D coordination polymers by two dtpo bridging ligands. Compound 6 contains mononuclear CdI2 units as nodes and can be viewed as an alternating copolymer of CdI2(μ-dtpo-κ2 O: O′)2 and CdI2(μ-dtpo-κ2 O: O′) entities. Owing to the disulfide moiety, the dtpo bridging ligand inevitably exhibits an axially chiral angular structure. The dtpo ligand adopts various coordination modes through the pyridine N-oxide oxygen atoms. [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]

The bottom-up synthesis of organometallic zinc clusters is described. The cation {[Zn10](Cp*)6Me}+ ( 1) is obtained by reacting [Zn2Cp*2] with [FeCp2][BAr4F] in the presence of ZnMe2. In the presence of suitable ligands, the high reactivity of 1 enables the controlled abstraction of single Zn units, providing access to the lower-nuclearity clusters {[Zn9](Cp*)6} ( 2) and {[Zn8](Cp*)5(tBuNC)3}+ ( 3). According to DFT calculations, 1 and 2 can be described as closed-shell species that are electron-deficient in terms of the Wade-Mingos rules because the apical ZnCp* units that constitute the cluster cage do not have three, but only one, frontier orbitals available for cluster bonding. Zinc behaves flexibly in building the skeletal metal-metal bonds, sometimes providing one major frontier orbital (like Group 11 metals) and sometimes providing three frontier orbitals (like Group 13 elements). [ABSTRACT FROM AUTHOR]

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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 triangular clusters [Zn3Cp*3]+ and [Zn2CuCp*3] were obtained by addition of the in situ generated, electrophilic, and isolobal species [ZnCp*]+ and [CuCp*] to Carmona's compound, [Cp*ZnZnCp*], without splitting the ZnZn bond. The choice of non-coordinating fluoroaromatic solvents was crucial. The bonding situations of the all-hydrocarbon-ligand-protected clusters were investigated by quantum chemical calculations revealing a high degree of σ-aromaticity similar to the triatomic hydrogen ion [H3]+. The new species serve as molecular building units of Cu nZn m nanobrass clusters as indicated by LIFDI mass spectrometry. [ABSTRACT FROM AUTHOR]

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The crystal structures of 5,10,15,20-tetra(4-hydroxyphenyl)-21,23H-porphyrin nitrobenzene hexasolvate (1), 5,10,15,20-tetra(4-hydroxyphenyl)porphyrinatonickel(II) nitrobenzene hexasolvate (2) and 5,10,15,20- tetra(4-hydroxyphenyl)porphyrinatocopper(II) nitrobenzene hexasolvate (3) are described. Compounds 1-3 crystallise isomorphously in the non-centrosymmetric tetragonal space group P4cc with Z = 8. There are three crystallographically distinct porphyrin molecules, two of which contain fourfold axes perpendicular to the porphyrin plane. The remaining one contains a twofold axis perpendicular to the porphyrin ring system. The porphyrin building blocks are joined into a three-dimensional network through self-complementary O-H...O hydrogen bonding interactions between 4-hydroxyphenyl groups of adjacent molecules. The space occupied by the nitrobenzene solvent molecules is remarkably large at ca. 61.5% of the unit cell volume in 1-3. [ABSTRACT FROM AUTHOR]

The first example of ligand protected Cu--Zn clusters is described. Reaction of [CpCu(CNt Bu)] with [Zn2Cp*2] yields [(CuCNtBu)4(ZnCp*)4] (1a) and [(CuCNt Bu)4(ZnCp*)3(ZnCp)] (1b). According to DFT calculations, the [Cu4Zn4] unit fulfils the unified superatom model for cluster valence shell closing. [ABSTRACT FROM AUTHOR]

A combined synchrotron X-ray and density functional theory (DFT) study on the structure of a Jäger-type N2O2 chelate complex was carried out. The ethoxy-substituted bis(3-oxo-enaminato)cobalt(II) complex ( 1) was an original sample from the laboratory of the late Professor Ernst-G. Jäger (University of Jena, Germany). Single-crystal X-ray analysis revealed essentially flat molecules of 1, which are unsolvated and coordinatively unsaturated. The DFT calculations on the isolated molecule predict a planar structure for the non-hydrogen atoms, which is a local minimum on the energy surface. The crystal packing is achieved through off-set stacking (staircase arrangement), resulting in a herringbone pattern in the space group P212121. The structure of 1 is compared to known structures of related bis(3-oxo-enaminato)cobalt(II) complexes ( 2- 4). Original bulk material of 1 was investigated by scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), melting point determination, and infrared (IR) spectroscopy. [ABSTRACT FROM AUTHOR]

Defined molecular models for the surface chemistry of Hume-Rothery nanophases related to catalysis are very rare. The Al-Cu intermetalloid cluster [(Cp*AlCu)6H4] was selectively obtained from the clean reaction of [(Cp*Al)4] and [(Ph3PCuH)6]. The stronger affinity of Cp*Al towards Cu sweeps the phosphine ligands from the copper hydride precursor and furnishes an octahedral Al6 cage to encapsulate the Cu6 core. The resulting hydrido cluster M12H4 reacts with benzonitrile to give the stoichiometric hydrometalation product [(Cp*AlCu)6H3(N=CHPh)]. [ABSTRACT FROM AUTHOR]

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Treatment of tetrakis(diethylamido)zirconium(IV); [Zr(NEt2)4] with a series of β-ketoimines ({[RHN]C- (CH3)vC(H)C(CH3)vO} where R is a functionalized side-chain; 4-(2-methoxyethylamino)pent-3-en-2-one, Hmeap; 4-(3-methoxypropylamino)pent-3-en-2-one, Hmpap; 4-(2-(dimethylamino)ethylamino)pent- 3-en-2-one, Hdeap; 4-(3-(dimethylamino)propylamino)pent-3-en-2-one, Hdpap) leads to an amine substitution reaction that yielded novel monomeric heteroleptic mixed amido-ketoiminato complexes of the type bis(4-(2-methoxyethylamino)pent-3-en-2-onato)bis(diethylamido)zirconium(IV) (1), bis(4-(3-methoxypropylamino) pent-3-en-2-onato)bis(diethylamido)zirconium(IV) (2), and bis(4-(3-(dimethylamino)propylamino) pent-3-en-2-onato)bis(diethylamido)zirconium(IV) (3), and eight-coordinated homoleptic complexes tetrakis(4-(2-methoxyethylamino)pent-3-en-2-onato)zirconium(IV) (4) and tetrakis(4-(2-(dimethylamino) ethylamino)pent-3-en-2-onato)zirconium(IV) (5), depending on the ratio of the ligand to zirconium. Adopting a similar strategy with zirconium alkoxide, namely [Zr(OiPr)4.iPrOH], with β-ketoimine Hmeap, leads to the formation of a dimer, bis(μ2-isopropoxo)bis(4-(2-methoxyethylamino)pent-3- en-2-onato)tetrakis(isopropoxo)dizirconium(IV) (6). The newly synthesised complexes were characterized by NMR spectroscopy, mass spectrometry, single crystal X-ray diffraction, elemental analysis and thermal analysis. The low decomposition temperature facilitated by the stepwise elimination of the ketominate ligand from the complex and the stability of the complexes obtained in air as well as in solution makes them highly suitable for solution based processing of ZrO2 thin films, which is demonstrated using compound 5 on Si(100) substrates. High quality ZrO2 films were obtained and were investigated for their structure, morphology, composition and optical properties. Low temperature crystallisation of ZrO2 is achieved by a simple chemical deposition process using the new class of Zr precursors and the films exhibit an optical transmittance above 90%. [ABSTRACT FROM AUTHOR]

The title compound, [Zn(SiF6)(C12H8N2)2]·CH3OH, contains a neutral heteroleptic tris-chelate ZnII complex, viz. [Zn(SiF6)(phen)2] (phen is 1,10-phenanthroline), exhibiting approximate molecular C2 point-group symmetry. The ZnII cation adopts a severely distorted octahedral coordination. As far as can be ascertained, the title complex represents the first structurally characterized example of a ZnII complex bearing a bidentate-bound hexafluorosilicate ligand. A density functional theory study of the isolated [Zn(SiF6)(phen)2] complex was undertaken to reveal the influence of crystal packing on the molecular structure of the complex. In the crystal structure, the methanol solvent molecule forms a hydrogen bond to one F atom of the hexafluorosilicate ligand. The hydrogen-bonded assemblies so formed are tightly packed in the crystal, as indicated by a high packing coefficient (74.1%). [ABSTRACT FROM AUTHOR]

Zn–Cp* bond cleavage reactions leading to novel monovalent cationic zinc species are presented (Cp* = pentamethylcyclopentadienyl). The treatment of [Zn2Cp*2] with two equiv. of [H(Et2O)2][BAr4F] (BAr4F = B{C6H3(CF3)2}4) yields the triple-decker complex [Cp*3Zn4(Et2O)2][BAr4F] (1) via protolytic removal of a Cp* ligand as Cp*H, whereas the reaction with an equimolar amount of [FeCp2][BAr4F] (Cp = cyclopentadienyl) results in the formation of [Cp*Zn2(Et2O)3][BAr4F] (2) under oxidative cleavage of a Cp* ring giving decamethylfulvalene, (Cp*)2, and [FeCp2] as by-products. The molecular structures of compounds 1 and 2 are established by single-crystal X-ray diffraction studies. A new synthetic pathway for the formation of [Zn2Cp*2] based on the reductive elimination of Cp*H from in situ formed Cp*ZnH is presented. [ABSTRACT FROM AUTHOR]

The title compound, [K(C14H23)(C4H8O)] n, comprises zigzag chains of alternating bridging 2,3,4,5-tetramethyl-1- n-pentylcyclopentadienyl ligands and potassium ions, with an ancillary tetrahydrofuran ligand in the coordination environment of potassium. The coordination polymer strands so formed extend by 21 screw symmetry in the b-axis direction. The chemically modified cyclopentadienyl ligand, with a tethered n-pentyl group, was synthesized from 2,3,4,5-tetramethylcyclopent-2-enone by a Grignard reaction. [ABSTRACT FROM AUTHOR]

4,4'-Dithiodipyridine (dtdp), also termed 4,4'-dipyridyldisulfide, is a bridging ligand of the 4,4'-bipyridine type. The introduction of the disulfide moiety inevitably leads to a relatively rigid angular structure, which exhibits axial chirality. More than 90 metal complexes containing the dtdp ligand have been crystallographically characterised until now. This review focuses on the preparation and structural diversity of discrete and polymeric metallosupramolecular assemblies constructed from dtdp as bridging ligands. These encompass metallamacrocycles with M2L2 topology and coordination polymers with periodicity in one or two dimensions. One-dimensional coordination polymers represent the vast majority of the metallosupramolecular structures obtained from dtdp. These include repeated rhomboids, zigzag, helical and arched chains among other types. In this contribution, we make an attempt to provide a comprehensive account of the structural data that are currently available for metallosupramolecular assemblies based on the bent bridging ligand dtdp [ABSTRACT FROM AUTHOR]

The photochemistry of 2,4,6-triazido-3,5-difluoropyridine 21 was investigated by matrix infrared and electron paramagnetic resonance spectroscopies. Ultraviolet irradiation (>260 nm) of 21 results in the formation of 3,5-difluoropyridyl-2,4,6-trinitrene 26 in yields high enough for characterization by infrared spectroscopy. The experimental infrared spectrum is in good agreement with density functional theory calculations. Under similar conditions, a very strong electron paramagnetic resonance spectrum of septet trinitrene 26 was obtained. Shorter irradiation times resulted in more complex product mixtures containing, in addition, mononitrenes and dinitrenes. Surprisingly, azirines and keteneimines, the typical photoproducts of arylnitrenes, were not observed. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]