Reaktive E=C (p-p)π-Systeme, XL. / Reactive E=C(p-p)π Systems, XL.

1995 ◽  
Vol 50 (1) ◽  
pp. 94-100 ◽  
Author(s):  
Thomas Albers ◽  
Joseph Grobe ◽  
Duc Le Van ◽  
Bernt Krebs ◽  
Mechtild Läge
Keyword(s):  
Molecular Structure ◽  
Main Product ◽  
Chloroform Solution ◽  
Lone Pair ◽  
Secondary Amines ◽  
Molar Ratio ◽  
Electronic Interaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Compounds

The reaction of bis(trifluoromethyl)arsane 2 with secondary amines R2NH in a molar ratio of 1:3 at -60 °C allows the preparation of trifluoromethyl arsaalkenes of the type F3CAs=C(F)NR2 in moderate yields (15-35%) [NR2 = NMe2 (3a), NMeEt (3b), NEt2 (3c)]. The main product of the reaction of 2 with Me2NH is the 1,1-diamino compound F3CAs=C(NMe2)2 (4a). With ethyl(isopropyl)- or di(isopropyl)amine the corresponding derivatives F3CAs=C(F)NEt(iPr) (3d) and F3CAs=C(F)N(iPr)2 (3e), respectively, are formed only in traces (3d), or not at all (3 e). However, 3d and 3e can be prepared by reacting perfluoro-2-arsapropene with the corresponding secondary amines. The new compounds 3 a to 3 e can be stored at 20 °C in chloroform solution for hours without decomposition and show Z configuration without exception. The molecular structure of 1-(diethylamino)-1,3,3,3-tetrafluoro-2-arsapropene 3c, determined by an X-ray diffraction study on single crystals, indicates a strong electronic interaction of the lone pair on nitrogen with the AsC double bond. This results in a trigonal planar arrangement at the nitrogen atom, a strongly shortened sp2-CN-bond (1.312 Å), an elongated AsC distance (1.867 Å), and an almost planar skeleton of the molecule.

Synthese und Kristallstrukturen einiger Tetramethylstibonium-Hydrogendicarboxylate / Synthesis and Crystal Structures of Some Tetramethylstibonium Hydrogendicarboxylates

1982 ◽  
Vol 37 (11) ◽  
pp. 1393-1401 ◽  
Author(s):  
Beatrix Milewski-Mahrla ◽  
Hubert Schmidbaur
Keyword(s):  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Spectroscopic Data ◽  
Molar Ratio ◽  
Ionic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carboxylate Oxygen ◽  
Donor Acceptor ◽  
New Compounds

Reactions of pentamethylantimony (CH3)5Sb with carboxylic acids in the molar ratio 1:2 afford one equivalent of methane and essentially quantitative yields of crystalline tetramothylstibonium hydrogendicarboxylates. Six new compounds of this series have been synthesized using benzoic, o-phthalic, salicylic, 4-ethoxy-salicylic, oxalic, and malic acid, and characterized by analytical and spectroscopic data. An ionic structure with strong hydrogen bonds in the anionic components is proposed.The crystal structures of the hydrogen-dibenzoato (1), hydrogen-ortho-plithalato (2) and 4-ethoxy-hydrogen-salicylate (3) were determined by single crystal X-ray diffraction. The compounds can be described as having ionic lattices with some donor-acceptor inter­actions between the stibonium centers and the carboxylate oxygen atoms. The anions are characterized by strong hydrogen bonds O...H...O. Thus, the (CH3)4Sb-tetrahedron in 1 is distorted by two benzoate oxygon atoms (at 304(2) and 340(2) pin). The cation in 2 is largely undistorted and the anion has a hydrogenphthalate hydrogen bond of d(O...H...O) = 232 pm. The cation-anion contact in 3 is as short as d(Sb-O) = 289 pm rendering the Sb atom pentacoordinate.

AlkalineEarthMetal-Hydride-Iodide Compounds: Syntheses andCrystal Structures of Sr2H3I and Ba5H2I3.9(2)O2

2011 ◽  
Vol 66 (1) ◽  
pp. 21-26
Author(s):  
Olaf Reckeweg ◽  
Francis J. DiSalvo
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Structural Model ◽  
Structure Type ◽  
Lattice Parameters ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
New Compounds

Single crystals of Sr2H3I andBa5H2I3.9(2)O2 were obtained by reacting Sr or Ba, respectively, with dried and sublimed NH4I in a 4 : 1 molar ratio in silica-jacketed Nb ampoules for 13 h at 1200 K. The crystal structures of the new compounds have been determined by means of single-crystal X-ray diffraction. Sr2H3I crystallizes in a stuffed anti-CdI2 structure isotypic to Ba2H3Cl in the space group P3m1 (no. 164) with the lattice parameters a = 426.0(1) and c = 774.9(2) pm, while Ba5H2I3.9(2)O2 crystallizes in a new structure type in the space group Cmcm (no. 63) with the lattice parameters a = 1721.0(2), b = 1452.5(2) and c = 639.03(9) pm. The structural results for Sr2H3I are corroborated by EUTAX calculations. For the disordered compound Ba5H2I3.9(2)O2, EUTAX calculations on an approximated, ordered structural model were used to find possible insights into the disorder

Synthesis and Structure of Pyrrolidinobromodiboranes(4)

2005 ◽  
Vol 60 (9) ◽  
pp. 1016-1019 ◽  
Author(s):  
Yong Nie ◽  
Hans Pritzkow ◽  
Walter Siebert
Keyword(s):  
Main Product ◽  
Molar Ratio ◽  
X Ray ◽  
New Compounds

The reaction of tetrapyrrolidinodiborane(4) (1) with BBr3 in a 1:1 molar ratio yields a mixture of 1,2-dibromo-1,2- dipyrrolidinodiborane(4) (2) and bromotripyrrolidino- diborane( 4) (3), while a 1:2 molar ratio leads in Et2O to compound 2 as the main product along with a small amount of [(C4H8N)2B2Br3(OEt)] (4). The new compounds have been characterized by NMR and MS data, as well as by X-ray structure analyses of 2 and 4, of which the former exhibits an interesting polymorphism phenomenon.

Synthesis and Pharmacological Evaluation of a Novel Series of Cyclopentenone Derivatives

2017 ◽  
Vol 41 (1) ◽  
pp. 50-56 ◽  
Author(s):  
Fatma A. El-Samahy ◽  
Marwa El-Hussieny ◽  
Naglaa F. El-Sayed ◽  
Elsayed M. Shalaby ◽  
Fayez H. Osman
Keyword(s):  
Mass Spectra ◽  
Secondary Amines ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Chemical Structures ◽  
Pharmacological Evaluation ◽  
New Compounds ◽  
C Nmr ◽  
Boiling Toluene

A novel series of cyclopent-2-enone derivatives have been synthesised by the reaction of 4-hydroxy-3,4-diphenylcyclopent-2-enone, cyclic secondary amines, phosphorus reagents, hexamethylphosphoramide and Lawesson's reagent in boiling toluene/THF. The chemical structures of new compounds were identified by 1H NMR, 13C NMR, 31P NMR and mass spectra. Furthermore, the structure of one of the synthesised compounds has been confirmed using single crystal X-ray diffraction. The pharmacological evaluation results of antilung and anticolon carcinoma cell line properties for the products are discussed.

Synthese und Struktur- und Konformationsanalyse von Triphenylphosphonium-bis(diphenylarsino)methylid

1984 ◽  
Vol 39 (11) ◽  
pp. 1456-1462 ◽  
Author(s):  
Hubert Schmidbaur ◽  
Peter Nußstein ◽  
Gerhard Müller
Keyword(s):  
Single Crystal ◽  
Spectroscopic Data ◽  
Heavy Atom ◽  
Lone Pair ◽  
Molar Ratio ◽  
Single Bond ◽  
X Ray Diffraction ◽  
Trans Conformation ◽  
X Ray ◽  
Lone Pairs

Abstract Triphenylphosphonium -diphenylarsinomethylide (1) and -bis-(diphenylarsino)methylide (2) are easily available through transylidation processes using Ph3P = CH2 and Ph2AsCl as the starting materials in the appropriate molar ratio. Analytical and spectroscopic data are presented for both ylides. The structure of 2 was studied in detail by single-crystal X-ray diffraction. The basic PCAs2 skeleton is found to deviate strongly from planarity. The Ph2As-substituents adopt a cis/trans conformation relative to the ylidic P = C bond with the directions of the lone pairs of electrons at the arsenic atoms in the heavy atom plane as expected for a maximum compensation of the electrostatic vectors. For 1, a cis-conformation of the lone pair of electrons and a large PCAs angle are predicted on the basis of NMR analogies with the phosphorus homologues. Single bond rotational barriers appear to be much lower for 1 and 2, however, than for the corresponding phosphino-substituted ylides.

Distorted amides as models for activated peptide N-C=O units. 2. The synthesis, hydrolytic profile, and molecular structure of 3,4-dihydro-2-oxo-1,4-propanoquinoline

1990 ◽  
Vol 68 (10) ◽  
pp. 1732-1739 ◽  
Author(s):  
Qingping Wang ◽  
A. J. Bennet ◽  
R. S. Brown ◽  
B.D. Santarsiero
Keyword(s):  
Molecular Structure ◽  
Rate Constant ◽  
Lone Pair ◽  
Protonated Form ◽  
X Ray Diffraction ◽  
X Ray ◽  
Amide Hydrolysis ◽  
Mechanism Of Hydrolysis

A distorted anilide (3,4-dihydro-2-oxo-1,4-propanoquinoline (3)) has been synthesized, its structure determined by X-ray diffraction, and its hydrolysis profile from pH 0–13 investigated. The amide unit in 3 is distorted in that the N lone pair is twisted 35° and tilted 15° out of optimum conjugation with the C=O II system. Due to this distortion, 3 hydrolyses rapidly in H2O at 25 °C. The pH/rate constant profile exhibits domains consistent with OH− attack on 3[Formula: see text] and H2O attack on a protonated form of 3[Formula: see text]; pKa (3-H+) = 0.56). The kinetic pKa is most consistent with an N-protonated form. It is also shown that this mechanism of hydrolysis is common to the series of bridged anilides consisting of 3, 3,4-dihydro-2-oxo-1,4-ethanoquinoline (1), and 2,3,4,5-tetrahydro-2-oxo-1,5-ethanobenzazepine (2). Keywords: distorted amide, hydrolysis, X-ray structure.

Bis[(2-diphenyIphosphino)phenyl]phenylphosphine as an Inflexible Tridentate Ligand for Indium Trichloride

1999 ◽  
Vol 54 (11) ◽  
pp. 1417-1419 ◽  
Author(s):  
Marcus Sigl ◽  
Annette Schier ◽  
Hubert Schmidbaur
Keyword(s):  
Spin System ◽  
Phosphorus Atom ◽  
Nmr Spectra ◽  
Lone Pair ◽  
Bidentate Ligand ◽  
Tridentate Ligand ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Ionic Complex ◽  
X Ray

Anhydrous indium trichloride reacts with [2-(Ph2P)C6H4]2PPh (TP) in the molar ratio 2:1 to give an ionic complex [(TP)InCl2]+ InCL4- in almost quantitative yield. The structure of the product has been determined by a single crystal X-ray diffraction study. In the cation the TP molecule acts only as a bidentate ligand via its two terminal phosphorus atoms [In-P1 2.5956(8), In-P2 2.5799(7) Å], Although the central phosphorus atom is also rather close to the metal atom [2.8259(8) Å], the In-P3 interaction is inefficient because of an adverse orientation of the lone pair of electrons at P3 owing to the steric inflexibility of the ligand. Accordingly, the 31P NMR spectra of the compound in CD2CI2 show large contact shifts and quadrupole broadening only for the signals of the two terminal phosphorus atoms, whereas the lines of the central phosphorus atom are less shifted and well resolved (AB2 spin system at -60°C).

Late metal salicylaldimine complexes derived from 5-aminosalicylic acid — Molecular structure of a zwitterionic mono Schiff base zinc complex

2005 ◽  
Vol 83 (8) ◽  
pp. 1063-1070 ◽  
Author(s):  
Tara A Bourque ◽  
Megan E Nelles ◽  
Teri J Gullon ◽  
Christian N Garon ◽  
Melissa K Ringer ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Schiff Base ◽  
Diffraction Study ◽  
Monoclinic Space Group ◽  
Aminosalicylic Acid ◽  
X Ray Diffraction ◽  
Compound A ◽  
Space Group ◽  
X Ray ◽  
New Compounds

Condensation of salicylaldehyde (2-HOC6H4C(O)H) with 5-aminosalicylic acid (5-H2NC6H3-2-(OH)-CO2H) afforded the Schiff base 2-HOC6H4C(H)=NC6H3-2-(OH)-5-CO2H (a). Similar reactivity with 5-bromosalicylaldehyde was also observed to give 5-Br-2-HOC6H3C(H)=NC6H3-2-(OH)-5-CO2H (b). Reaction of these salicylaldehydes with Pd(II), Cu(II), and Zn(II) salts gave the corresponding bis(N-arylsalicylaldiminato)metal complexes (M = Pd (1), Cu (2), Zn (3)). The molecular structure of the Schiff base compound a has been confirmed by an X-ray diffraction study. Crystals of a were monoclinic, space group P2(1)/c, a = 7.0164(7) Å, b = 11.0088(11) Å, c = 14.8980(15) Å, β = 102.917(2)°, Z = 4. The molecular structure of a novel zwitterionic conformer of 3a was also characterized by an X-ray diffraction study. Crystals of 4 were monoclinic, space group P2(1)/c, a = 9.5284(5) Å, b = 19.5335(11) Å, c = 8.6508(5) Å, β = 90.596(1)°, Z = 4. All new compounds have been tested for their antifungal activity against Aspergillus niger and Aspergillus flavus. Key words: 5-aminosalicylic acid (5-ASA), antifungal, copper, palladium, salicylaldimines, Schiff base, zinc.

Crystal and Molecular Structure of Lithium Benzohydroxamate-Benzohydroxamic Acid (1 : 1) Adduct

1996 ◽  
Vol 61 (1) ◽  
pp. 139-146 ◽  
Author(s):  
Roman Řeřicha ◽  
Ivana Císařová ◽  
Jaroslav Podlaha
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Hydrogen Bond ◽  
Crystal And Molecular Structure ◽  
Molecular Geometry ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Benzohydroxamic Acid ◽  
Short Hydrogen Bond

The crystal structure of the title compound was determined by single crystal X-ray diffraction. It consists of molecules of benzohydroxamic acid, its O-deprotonated anions and lithium cations in the 1 : 1 : 1 molar ratio. Although the molecular geometry of the anion is very similar to that of the acid, these units can be unambiguously distinguished since the short hydrogen bond between the OH group of the acid and the N-bonded oxygen atom of the anion is remarkably asymmetric. This bond, together with the lithium cations (being surrounded by five oxygens), links the units into chains running in the crystallographic ab plane. The coordination polyhedron around Li represents a rare example of an almost undistorted LiO5 square pyramidal arrangement.

Convenient Synthesis and Molecular Structure of the Cyclometallated Complex [IrCl(H)(C6H4PPh2)(PPh3)2]

2014 ◽  
Vol 69 (11-12) ◽  
pp. 1237-1240 ◽  
Author(s):  
Hans-Christian Böttcher ◽  
Peter Mayer
Keyword(s):  
Molecular Structure ◽  
Reaction Time ◽  
Title Compound ◽  
Room Temperature ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Short Reaction Time ◽  
X Ray ◽  
Convenient Synthesis ◽  
Cyclometallated Complex

Abstract The reaction of [{Ir(μ-Cl)(coe)2}2] (coe=cis-cyclooctene) with triphenylphosphane (molar ratio of Ir to P=1 : 3) in dichloromethane at room temperature afforded after a short reaction time the cyclometallated complex [IrCl(H)(C6H4PPh2)(PPh3)2] (1) in almost quantitative yield. The molecular structure of the title compound 1 was determined by an X-ray diffraction study.

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