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1.  N-(2-Nitro­phen­yl)thio­phene-2-carbox­amide 
The title compound, C11H8N2O3S, shows two mol­ecules per asymmetric unit, with the dihedral angles between the benzene and thio­phene rings of 13.53 (6) and 8.50 (5)° being a notable difference between them. An intra­molecular N—H⋯O hydrogen-bond in each mol­ecule generates an S(6) ring motif. The crystal packing shows no classical hydrogen bonds with the mol­ecules being packed to form weak C—H⋯O and C—H⋯S inter­actions leading to R 2 2(9) and R 4 4(25) rings which are edge-shared, giving layers parallel to (010).
PMCID: PMC4011230  PMID: 24860404
2.  4-Bromo-N-(2-nitro­phen­yl)benzamide 
The title nitro­phenyl benzamide, C13H9BrN2O3, with two mol­ecules in the asymmetric unit, has dihedral angles of 16.78 (15) and 18.87 (14)° between the benzene rings. An intra­molecular N—H⋯O hydrogen bond is observed in each mol­ecule. In the crystal, the molecules are linked by weak C—H⋯O inter­actions; halogen–halogen inter­actions are also observed [Br⋯Br = 3.4976 (7) Å]. These inter­actions form R 2 2(10), R 2 2(15) and R 6 6(32) edge-fused rings along [010].
PMCID: PMC3998505  PMID: 24765035
3.  4-Formyl-2-nitro­phenyl benzoate 
In the title nitroaryl benzoate derivative, C14H9NO5, the aromatic rings form a dihedral angle of 46.37 (8)°. The central ester moiety, —C—(C=O)—O—, is essentially planar (r.m.s. deviation for all non-H atoms = 0.0283 Å) and forms a dihedral angle of 54.06 (9)° with the 4-formyl-2-nitro­phenyl ring and 7.99 (19)° with the benzoate ring. In the crystal, mol­ecules are inter­twined by weak C—H⋯O inter­actions, forming helical chains along [100].
PMCID: PMC3998475  PMID: 24764983
4.  3,4-Di­methyl­phenyl benzoate 
In the title compound, C15H14O2, the terminal rings form a dihedral angle of 52.39 (4)°. The mean plane of the central ester group [r.m.s. deviation = 0.0488 Å] is twisted away from the benzene and phenyl rings by 60.10 (4) and 8.67 (9)°, respectively. In the crystal, mol­ecules are linked by weak C—H⋯O hydrogen bonds, forming C(6) chains which run along [100].
PMCID: PMC3998344  PMID: 24764905
5.  4-Formyl-2-nitro­phenyl 3-nitro-2-methyl­benzoate 
In the title formyl nitro aryl benzoate derivative, C15H10N2O7, the benzene rings form a dihedral angle of 4.96 (3)°. The mean plane of the central ester group, C—O—C–(=O)—C (r.m.s. deviation = 0.0484 Å), is twisted away from the formyl nitro aryl and benzoate rings by 46.61 (5) and 49.93 (5)°, respectively. In the crystal, the mol­ecules are packed forming C—H⋯O inter­actions in chains which propagate along [010]. Edge-fused R 3 3(15) rings are generated along this direction.
PMCID: PMC3914067  PMID: 24526968
6.  2,4,6-Tri­nitro­phenyl furan-2-carboxyl­ate 
In the title carboxyl­ate derivative, C11H5N3O9, the picryl ring forms an angle of 75.79 (7)° with the ester fragment, indicating a near perpendicular disposition. The nitro substituents are variously oriented with respect to the picryl ring [dihedral angles = 3.22 (10), 16.03 (12) and 36.63 (10)°]. In the crystal, mol­ecules form helical chains sustained by C—H⋯O inter­actions along [010]. The furanyl residue is disordered, having two coplanar slightly displaced orientations [major component = 0.730 (9)].
PMCID: PMC3884337  PMID: 24454113
7.  N-(2-Nitro­phen­yl)furan-2-carboxamide 
In the title furan­carboxamide derivative, C11H8N2O4, the benzene and furan rings are rotated from the mean plane of the central fragment by 2.68 (5) and 7.03 (4)°, respectively. The nitro group forms a dihedral angle of 10.15 (5)° with the adjacent benzene ring. In the crystal, mol­ecules are linked by weak C—H⋯O inter­actions, forming helical chains running along [010].
PMCID: PMC3790447  PMID: 24098266
9.  Structural Tracking of the Potassium-Mediated Magnesiation of Anisole 
PMCID: PMC3784043  PMID: 19746488
crystal structure; magnesiation; metalation; NMR spectroscopy; potassium
10.  Structurally Defined Potassium-Mediated Zincation of Pyridine and 4-R-Substituted Pyridines (R=Et, iPr, tBu, Ph, and Me2N) by Using Dialkyl–TMP–Zincate Bases 
Two potassium–dialkyl–TMP–zincate bases [(pmdeta)K(μ-Et)(μ-tmp)Zn(Et)] (1) (PMDETA=N,N,N′,N′′,N′′-pentamethyldiethylenetriamine, TMP=2,2,6,6-tetramethylpiperidide), and [(pmdeta)K(μ-nBu)(μ-tmp)Zn(nBu)] (2), have been synthesized by a simple co-complexation procedure. Treatment of 1 with a series of substituted 4-R-pyridines (R=Me2N, H, Et, iPr, tBu, and Ph) gave 2-zincated products of the general formula [{2-Zn(Et)2-μ-4-R-C5H3N}2⋅2{K(pmdeta)}] (3–8, respectively) in isolated crystalline yields of 53, 16, 7, 23, 67, and 51%, respectively; the treatment of 2 with 4-tBu-pyridine gave [{2-Zn(nBu)2-μ-4-tBu-C5H3N}2⋅2{K(pmdeta)}] (9) in an isolated crystalline yield of 58%. Single-crystal X-ray crystallographic and NMR spectroscopic characterization of 3–9 revealed a novel structural motif consisting of a dianionic dihydroanthracene-like tricyclic ring system with a central diazadicarbadizinca (ZnCN)2 ring, face-capped on either side by PMDETA-wrapped K+ cations. All the new metalated pyridine complexes share this dimeric arrangement. As determined by NMR spectroscopic investigations of the reaction filtrates, those solutions producing 3, 7, 8, and 9 appear to be essentially clean reactions, in contrast to those producing 4, 5, and 6, which also contain laterally zincated coproducts. In all of these metalation reactions, the potassium–zincate base acts as an amido transfer agent with a subsequent ligand-exchange mechanism (amido replacing alkyl) inhibited by the coordinative saturation, and thus, low Lewis acidity of the 4-coordinate Zn centers in these dimeric molecules. Studies on analogous trialkyl–zincate reagents in the absence and presence of stoichiometric or substoichiometric amounts of TMP(H) established the importance of Zn–N bonds for efficient zincation.
PMCID: PMC3784044  PMID: 19533716
alkali metals; metalation; potassium; pyridine; zincation
11.  12-(2-Hy­droxy-6-oxo­cyclo­hex-1-en­yl)-9,10-di­hydro-8H-benzo[a]xanthen-11(12H)-one 
In the xanthenone system of the title compound, C23H20O4, the pyran ring has a maximum deviation of 0.111 (1) Å from planarity and the outer cyclo­hexene ring exhibits a puckered conformation. The three methyl­ene C atoms of the cyclo­hexene ring bonded to the pyran unit are disordered over two sets of sites [occupancies = 0.570 (3) and 0.430 (3)]. In the crystal, mol­ecules are linked by C—H⋯O and O—H⋯O hydrogen bonds, forming a two-dimensional network parallel to (110). A C—H⋯π inter­action occurs between these networks.
PMCID: PMC3790420  PMID: 24098239
12.  Developing a Hetero-Alkali-Metal Chemistry of 2,2,6,6-Tetramethyl-piperidide (TMP): Stoichiometric and Structural Diversity within a Series of Lithium/Sodium, Lithium/Potassium and Sodium/Potassium TMP Compounds 
Studied extensively in solution and in the solid state, Li(TMP) (TMP=2,2,6,6-tetramethylpiperidide) is an important utility reagent popular as a strongly basic, weakly nucleophilic tool for C–H metallation. Recently, there has been a surge in interest in mixed metal derivatives containing the bulky TMP anion. Herein, we start to develop hetero (alkali metal) TMP chemistry by reporting the N,N,N′,N′-tetramethylethylenediamine (TMEDA)-hemisolvated sodium–lithium cycloheterodimer [(tmeda)Na(μ-tmp)2Li], and its TMEDA-free variant [{Na(μ-tmp)Li(μ-tmp)}∞], which provides a rare example of a crystallographically authenticated polymeric alkali metal amide. Experimental observations suggest that the former is a kinetic intermediate en route to the latter thermodynamic product. Furthermore, a third modification, the mixed potassium–lithium-rich cycloheterotrimer [(tmeda)K(μ-tmp)Li(μ-tmp)Li(μ-tmp)], has also been synthesised and crystallographically characterised. On moving to the bulkier tridentate donor N,N,N′,N′′,N′′-pentamethyldiethylenediamine (PMDETA), the additional ligation forces the sodium–lithium and potassium–dilithium ring species to open giving the acyclic arc-shaped complexes [(pmdeta)Na(μ-tmp)Li(tmp)] and [(pmdeta)K(μ-tmp)Li(μ-tmp)Li(tmp)], respectively. Completing the series, the potassium–lithium and potassium–sodium derivatives [(pmdeta)K(μ-tmp)2M] (M=Li, Na) have also been isolated as closed structures with a distinctly asymmetric central MN2K ring. Collectively, these seven new bimetallic compounds display five distinct structural motifs, four of which have never hitherto been witnessed in TMP chemistry and three of which are unprecedented in the vast structural library of alkali metal amide chemistry.
PMCID: PMC3761191  PMID: 21766365
aggregation; alkali metals; amides; heterometallic complexes; X-ray diffraction
13.  1-{(E)-[(2-Fluoro-5-nitro­phen­yl)imino]­meth­yl}naphthalen-2-ol 
The title mol­ecule, C17H11FN2O3, is nearly planar [maximum deviation = 0.197 (1) Å] and the mol­ecular conformation is stabilized by an N—H⋯O hydrogen bond forming an S(6) ring motif. The H atom of the intra­molecular hydrogen bond was found to be disordered over two sites and thus both the hy­droxy and keto tautomers are simultaneously present in the solid. Refinement of the occupancy of this site suggests that the hy­droxy form is the major component [occupancy refined to 0.59 (3):0.41 (3)]. Bond lengths are also largely consistent with dominance of the hy­droxy form. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds, forming layers parallel to (101). π–π stacking inter­actions [centroid–centroid distances = 3.5649 (9) and 3.7579 (9) Å] inter-connect these layers.
PMCID: PMC3684934  PMID: 23795036
14.  14-Bromo-12-chloro-2,16-dioxa­penta­cyclo­[,21.03,8.010,15]henicosa-3(8),10,12,14-tetra­ene-7,20-dione 
In the title compound, C19H16BrClO4, both the fused xanthene rings and one of the cyclo­hexane rings adopt envelope conformations, while the other cyclo­hexane ring is in a chair conformation. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds, forming infinite chains running along [10-1] incorporating R 2 2(16) ring motifs. In addition, C—H⋯π inter­actions and weak π–π stacking inter­actions [centroid–centroid distance = 3.768 (3) Å] help to consolidate the packing.
PMCID: PMC3648294  PMID: 23723914
15.  3-Amino-1-phenyl-1H-benzo[f]chromene-2-carbonitrile 
In the title compound, C20H14N2O, the phenyl ring is almost normal to the naphthalene ring system with a dihedral angle of 86.72 (9)°. The 4H-pyran ring fused with the naphthalene ring system has a boat conformation. In the crystal, mol­ecules are linked into a helical supra­molecular chain along the b axis via N—H⋯N hydrogen bonds. The chains are consolidated into a three-dimensional architecture by C—H⋯π inter­actions.
PMCID: PMC3588429  PMID: 23476583
16.  2,4,6-Trinitro­phenyl benzoate 
In the title mol­ecule, C13H7N3O8, the phenyl and benzene rings are rotated from the mean plane of the central ester group by 18.41 (9) and 81.80 (5)°, respectively. The dihedral angle between the rings is 80.12 (14)°. In the crystal, mol­ecules are linked by weak C—H⋯O inter­actions, forming helical chains along [010].
PMCID: PMC3589064  PMID: 23476300
17.  4-Phenyl-1H-1,5-benzodiazepin-2(3H)-one 
In the title compound, C15H12N2O, the phenyl ring makes a dihedral angle of 32.45 (9)° with the benzene ring of the 1,5-benzodiazepin-2-one unit. The seven-membered ring adopts a boat conformation with the methyl­ene group as the prow and the fused benzene-ring C atoms as the stern. In the crystal, inversion dimers linked by pairs of N—H⋯O hydrogen bonds generate R 2 2(8) loops. The dimers are further linked by C—H⋯O hydrogen bonds, so forming a column along the a-axis direction.
PMCID: PMC3588955  PMID: 23476191
18.  catena-Poly[sodium-μ2-(N,N,N′,N′-tetra­methyl­ethane-1,2-diamine)-κ2 N:N′-sodium-bis­[μ2-bis­(trimethyl­sil­yl)aza­nido-κ2 N:N]] 
The title compound, [Na2(C6H18NSi2)2(C6H16N2)]n, was found to consist of dimeric [Na(NSiMe3)2] units with crystallographically imposed centrosymmetry based upon four-membered NaNNaN rings. The dimers are bridged by N,N,N′,N′-tetra­methyl­ethylenediamine ligands, which act in an unusual extended non-chelating coordination mode. This gives a one-dimensional coordination polymer that extends parallel to the a-axis direction.
PMCID: PMC3588730  PMID: 23468695
19.  Diethyl 3,4-dimethyl­thieno[2,3-b]thio­phene-2,5-dicarboxyl­ate 
In the title compound, C14H16O4S2, the thieno[2,3-b]thio­phene ring systems are planar [maximum deviation = 0.008 (2) Å]. The mol­ecular conformation is stabilized by intra­molecular C—H⋯O hydrogen bonds, while the crystal packing is stabilized by C—H⋯O, C—H⋯π and π–π stacking [centroid–centroid distance = 3.6605 (14) Å] inter­actions, which lead to supra­molecular layers in the ab plane.
PMCID: PMC3588935  PMID: 23476171
20.  4-Bromo-2-[(E)-{[4-nitro-2-(trifluoro­meth­yl)phen­yl]imino}­meth­yl]phenol 
Except two F atoms of the –CF3 group, the title compound, C14H8BrF3N2O3, has an almost planar conformation, the dihedral angle between the aromatic rings being 3.60 (16)°. The mol­ecule adopts the enol–imine tautomeric form, with an intra­molecular O—H⋯N hydrogen bond, which generates an S(6) ring motif. In the crystal, face-to-face π–π stacking [centroid–centroid distances = 3.669 (2) and 3.732 (2) Å] between the aromatic rings of the mol­ecules, which lie in sheets parallel to (202), help to establish the packing.
PMCID: PMC3515262  PMID: 23284482
21.  1-Benzyl­piperidin-4-one O-(2-bromo­benz­yl)oxime 
In the title mol­ecule, C19H21BrN2O, the piperidone ring adopts a chair conformation with a total puckering amplitude Q T of 0.554 (2) Å. The dihedral angle between the benzene rings is 64.10 (7)°. There are no significant inter­molecular inter­actions.
PMCID: PMC3470391  PMID: 23125804
22.  2-Amino­ethanaminium iodide 
The title salt, [NH3CH2CH2NH2]+·I−, has an array structure based on strong inter­molecular N—H⋯N hydrogen bonding formed between the ammonium and amine groups of adjacent cations. This inter­action gives a helical chain of cations that runs parallel to the b axis. The four remaining NH group H atoms all form hydrogen bonds to the iodide anion, and these iodide anions lie in channels parallel to the cation–cation chains.
PMCID: PMC3379320  PMID: 22719518
23.  (E)-Benzaldehyde O-{[3-(pyridin-3-yl)isoxazol-5-yl]meth­yl}oxime 
The asymmetric unit of the title compound, C16H13N3O2, contains two independent mol­ecules in which the pyridine and benzene rings form dihedral angles of 81.7 (2) and 79.8 (2)°, indicating the twist in the mol­ecules. In the crystal, weak C—H⋯N inter­actions link mol­ecules into chains along [100].
PMCID: PMC3344035  PMID: 22589944
24.  1,4-Dimethyl­piperazin-1-ium 3-hy­droxy-2-naphtho­ate 
The reaction of 1,4-dimethyl­piperazine and 3-hy­droxy-2-naphthoic acid gives the title 1:1 salt, C6H15N2 +·C11H7O3 −, with a singly protonated piperazinium cation. In the crystal, a single N—H⋯O hydrogen bond links the cations and anions into discrete pairs and the aromatic anions stack along the crystallographic a-axis direction. This results in layers of cations and anions alternating along the crystallographic c-axis direction. An intra­molecular O—H⋯O hydrogen bond is also present.
PMCID: PMC3297856  PMID: 22412659
25.  2-Bromo-N-(4-chloro­phen­yl)-2-methyl­propanamide 
In the title mol­ecule, C10H11BrClNO, there is a twist between the mean plane of the amide group and the benzene ring [C(=O)—N—C—C torsion angle = −27.1 (3)°]. In the crystal, inter­molecular N—H⋯O and weak C—H⋯O hydrogen bonds link the mol­ecules into chains along [010].
PMCID: PMC3201238  PMID: 22064690

Results 1-25 (49)