1,720,986 research outputs found
X-Ray Structure Determinations of Bromo- and/or Bromomethyl-substituted Benzenes: C-H center dot center dot center dot Br, C-Br center dot center dot center dot Br, and C-Br center dot center dot center dot pi Interactions
No full textZ. Naturforsch. 2012, 67b, 1273-1281 / DOI: 10.5560/ZNB.2012-0249 Received September 18, 2012 Belatedly dedicated to Professor Joachim Heinicke on the occasion of his 65th birthday The structures of seven benzene derivatives [1,2,3-tri(bromomethyl)benzene, (1); 3,5-di(bromomethyl)bromobenzene, (2); 2,5-di(bromomethyl)bromobenzene, (3); 4-(bromomethyl)-2,5-dibromotoluene, (4); 4-(bromomethyl)bromobenzene, (5); 2,3-di(bromomethyl)bromobenzene, (6) and (bromomethyl)-p-dibromobenzene, (7)] with bromo and bromomethyl (and in one case methyl) substituents are presented and analysed in terms of Br center dot center dot center dot Br interactions up to 4.0 angstrom, supported by hydrogen bonds H center dot center dot center dot Br. Some interactions of the type Br center dot center dot center dot pi and pi center dot center dot center dot pi are encountered and play a subordinate role in the packing. Despite the close chemical similarity of the compounds, some of which are isomers with permuted substituent positions, the packing motifs are highly variable. Compounds 2-5 are based on layer structures with Br-n (n = 3, 4) and/or mixed Br/C rings. Compounds 1, 6 and 7 display three-dimensional packings of differing complexity, but with interpretable substructures; 1 can be analysed in terms of ribbons of linked Br-3 and Br-4 rings; 6 displays chains of linked Br-3 triangles; 7 consists of ribbons of linked Br-4 quadrilaterals
Diazadioxacyclophanes
No full textSix new cyclophane molecules (5-10) were synthesized from alpha,alpha'-bis(N-tosyl-4-aminophenyl)-1,4-diisopropylbenzene and alpha,alpha'-bis[4-(n-bromoalkyloxy)phenyl]-1,4-diisopropylbenzene. The crystal and molecular structures of alpha,alpha'-bis(4-aminophenyl)-1,4-diisopropylbenzene (3), alpha,alpha'-bis (N-tosyl-4-aminophenyl)-1,4-diisopropylbenzene 4 and the ditosyl derivative of the diazadioxacyclophane 6 were determined. The noncyclic compounds 3 and 4 display the ami conformation. Diazadioxacyclophane 6 possesses a central cavity that might be exploited to accommodate guest molecules, but some conformational change would probably be required.The Welch Foundation [Grant D-0775
Three Crystal Structures of Terephthalic Acid Salts of Simple Amines
No full textDiphenethylamine forms two adducts (1 : 1, la and 2 : 1, 1b) with terephthalic acid (H(2)TPA). The former is bis(diphenethylammonium)H-2 TPA center dot TPA(2-) and the latter is bis(diphenethylammonium)center dot TPA(2-). The amine cis-2,6-dimethylpiperidine forms a hydrated 2 : 1 adduct, bis(2,6-dimethylpiperidinium)center dot TPA(2-)center dot H2O (2). The crystal structures of all three compounds were determined. All H(2)TPA and TPA(2-) residues display inversion symmetry, while the water oxygen atom of 2 lies on a twofold axis. Packing analyses have identified some supramolecular synthons known from related structures
Crystallographic characterization and identification of a minor isomer of C(84) fullerene
No full textWe report the synthesis and single crystal X-ray analysis of C(84) (14)center dot AgTPP (Ag tetraphenylporphyrin) cocrystal-the first ordered crystal structure containing a pristine higher fullerene
Diazadioxacyclophanes
No full textSix new cyclophane molecules (5-10) were synthesized from alpha,alpha'-bis(N-tosyl-4-aminophenyl)-1,4-diisopropylbenzene and alpha,alpha'-bis[4-(n-bromoalkyloxy)phenyl]-1,4-diisopropylbenzene. The crystal and molecular structures of alpha,alpha'-bis(4-aminophenyl)-1,4-diisopropylbenzene (3), alpha,alpha'-bis (N-tosyl-4-aminophenyl)-1,4-diisopropylbenzene 4 and the ditosyl derivative of the diazadioxacyclophane 6 were determined. The noncyclic compounds 3 and 4 display the ami conformation. Diazadioxacyclophane 6 possesses a central cavity that might be exploited to accommodate guest molecules, but some conformational change would probably be required.The Welch Foundation [Grant D-0775
Polysulfonylamines, CLXXXII [1]. Bis(triphenylphosphoranylidene)ammonium di(4-fluorobenzenesulfonyl)amide: Two polymorphs featuring different conformations of the cation and the anion
No full textTwo polymorphs A and B of the previously unreported compound [Ph3PNPPh3](+)[(4-F-C6H4SO2)(2)N](-) have been revealed by serendipity (form A: triclinic, space group P (1) over bar, Z' = 1; form B: monoclinic, space group P2(1) In, Z' = 1). Conformational flexibility of both the cation and the anion appears to facilitate polymorph formation. The (C3P)(2)N moiety of the cation, as viewed down P... P, is ecliptic in A but staggered in B, whereas the extended conformations of the anion (C-S... S'-C' antiperiplanar) display notably different torsion angles about the S-N and the S-C bonds. Each structure is characterized by an extensive network of weak C-H... O/N/F hydrogen bonds and CH/pi interactions. The packing of A consists of cation monolayers that intercalate parallel chains of anions. In contrast, polymorph B forms homoionic strands, whereby each strand comprises two ion chains and is surrounded by four parallel strands of opposite charge
pi-Excess sigma P-2,O Hybrid Ligands: Synthesis of the First 4-Methoxy-1H-1,3-benzazaphospholes
No full textThe synthesis of the first 4-methoxy-substituted 1,3-benzazaphosphole was accomplished by using a C, O-dilithium intermediate generated from N-(3-methoxyphenyl)-2,2-dimethylpropanamide and butyllithium. This intermediate was subjected either to direct phosphonylation or to a bromination and phosphonylation sequence; subsequent reductive cyclization with excess lithium aluminum hydride led to the desired product. In addition, N-(2,2-dimethylpropyl)-3-methoxy-2-phosphinoaniline, formed in a side reaction, was cyclized with (dimethoxymethyl) dimethylamine to give 1-(2,2-dimethylpropyl)-4-methoxy-1H-1,3-benzazaphosphole. The behavior of these +M-substituted pi-excess aromatic sigma P-2-heterocycles towards moisture is reported, together with their H-1, C-13, and P-31 solution NMR spectra and a crystal-structure analysis. The new compounds represent potential sigma P-2, O hybrid or chelate ligands with a high pi-density at the phosphorus atom.Deutsche Forschungsgemeinschaft [HE 1997/12
A Simple System with many Structural Variants: A Reexamination of (Amine)halogenidosilver(I) Complexes
No full textWe report the structures of nineteen new amine silver halide complexes, some of them featuring previously unknown structure types, stoichiometries (such as L(4)Ag(5)X(5)) and coordination numbers. Known structures have been included and analysed for non-classical hydrogen bonds. We have identified three important factors for the formation of certain structure types. First, Ag-X bonds that form a central framework, typically staircase-shaped. Secondly, hydrogen bonds or other secondary interactions competing with these leading to a weakening or disappearance of some of the central Ag-X bonds. Finally, the polarity of the substituent at nitrogen and the silver halides influence the stoichiometry of the complex
Bulky N-substituted 1,3-benzazaphospholes: Access via Pd-catalyzed C-N and C-P cross coupling, lithiation, and conversion to novel P=C-PtBu2 hybrid ligands
No full textThe syntheses of novel bulky N-substituted 1,3-benzazaphospholes are presented, together with their reactions with tert-butyllithium and coupling with tBu(2)PCI to novel PP-hybrid ligands that combine the highly basic and bulky di-tert-butylphosphanyl group with g-acidic low-coordinated phosphorus. The syntheses start with the preparation of new N-seconclary 2-bromoanilines 1 by reduction of N-acyl 2-bromoanilides or more generally by Pd-catalyzed selective monoamination of o-dibromobenzene, followed by Pd-catalyzed C-P coupling with P(OEt)(3) to the respective 2-anilino-phosphonates 2. The next steps are reduction to 2-phosphanylanilines 3 and condensation with Me2NCH(OMe)(2), which leads via phosphaalkenes 4 to the corresponding N-substituted benzazaphospholes 5. The reaction with tBuLi depends on the steric demand of the N substituent. Methyl, neopentyl-, and mesityl-derivatives were converted to P=C Li species 6 and coupled with tBu(2)PCI to novel P=C-PtBU2 ligands 7, whereas N-adamany and N-2,6-diisopropylphenyl-derivatives prefer addition of tBuLi at the P=C bond to form dihydroderivatives. The chemical shifts of the low-coordinated phosphorus of 5 and 7 were found to reflect electronic and steric effects of the N substituents. The comparison of the crystal structures of N-neopentyl-1,3-benzazaphospholes 5 and 7 gives evidence of steric repulsion between the adjacent di-tert-butyl and neopentyl groups by the preferred anti orientation of the P-tert-butyl groups and moderate deviations of C2 and P3 of 7b from the ring plane
A Simple System with many Structural Variants: A Reexamination of (Amine)halogenidosilver(I) Complexes
No full textWe report the structures of nineteen new amine silver halide complexes, some of them featuring previously unknown structure types, stoichiometries (such as L(4)Ag(5)X(5)) and coordination numbers. Known structures have been included and analysed for non-classical hydrogen bonds. We have identified three important factors for the formation of certain structure types. First, Ag-X bonds that form a central framework, typically staircase-shaped. Secondly, hydrogen bonds or other secondary interactions competing with these leading to a weakening or disappearance of some of the central Ag-X bonds. Finally, the polarity of the substituent at nitrogen and the silver halides influence the stoichiometry of the complex
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