scholarly journals I. The low temperature photochemistry of iron pentacarbonyl and disubstituted acetylenes, II. The X-ray structure determination of trans-6,8-dibromo-1,2,3,4,4a,9a-hexahydro-4a,9-dimethylcarbazole

1971 ◽  
Author(s):  
Allen Bloom
Keyword(s):  
Low Temperature ◽  
Structure Determination ◽  
Iron Pentacarbonyl ◽  
X Ray

4,4′-Bithiazoles as Ligands: Crystal and Molecular Structure of bis(O,O′-Nitrato)(2,2′-diphenyl-4,4′-bithiazole)copper(II) (Two Polymorphs)

2003 ◽  
Vol 56 (9) ◽  
pp. 949 ◽  
Author(s):  
S. Ali Asghar Torabi ◽  
Fahimeh Jamali ◽  
George A. Koutsantonis ◽  
Ali Morsali ◽  
Brian W. Skelton ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Low Temperature ◽  
Molecular Complex ◽  
Structure Determination ◽  
Crystal And Molecular Structure ◽  
Plane Angle ◽  
Asymmetric Unit ◽  
X Ray ◽  
Crystallographic Symmetry

A low-temperature single-crystal X-ray structure determination of the 1 : 1 adduct of copper(II) nitrate with 2,2′-diphenyl-4,4′-bithiazole (L) shows it to be a molecular complex with L behaving as a symmetrical N,N′ chelate, and the nitrate groups as unsymmetrical O,O′ chelates: [LCu(O2NO)2]. Two polymorphs, both monoclinic P21/c, have been obtained from acetonitrile (‘α’) and methanol (‘β’), respectively, with one molecule, devoid of crystallographic symmetry, in the asymmetric unit of each structure. The copper environments are distorted planar four-coordinate, cis-N2CuO2 (Cu–N 2.011(1), 1.973(1), Cu–O 1.995(1), 1.962(1) Å), ‘in-plane’ angle sum Σ 369.5°, with longer trans, axial contacts (Cu–O 2.455(1), 2.458(2) Å) for the α-form; respective values are 1.995(5), 1.991(4), 1.997(4), 1.973(3) Å, 360.4°, 2.500(4), and 2.396(4) Å for the β-form.

Simple Method for the Handling of Crystals at Low Temperature: Application to the X-Ray Structure Determination of But2P(=NSiMe3)NHSiMe3 and [But2P(NSiMe3)2]Li·(thf)2

2002 ◽  
Vol 55 (4) ◽  
pp. 249 ◽  
Author(s):  
A. J. Edwards ◽  
E. Wenger
Keyword(s):  
Low Temperature ◽  
Data Collection ◽  
Structure Determination ◽  
Molecular Structures ◽  
Simple Method ◽  
Dry Ice ◽  
X Ray ◽  
Temperature Application

Crystals of the very soluble iminophosphonamide species But2P(=NSiMe3)NHSiMe3 (1) and [But2P(NSiMe3)2]Li�(thf)2 (2) have been obtained and were mounted at dry-ice temperature using a propan-2-ol matrix for X-ray data collection at 100 K. This very simple method for handling the crystals at low temperature is described together with the resulting molecular structures of (1) and (2).

The protonation of the ethylenediphosphinetetraacetate anion and the crystal structure of the bis (hydrogen bromide) of ethylenediphosphinetetraacetic acid

1981 ◽  
Vol 46 (12) ◽  
pp. 3063-3073 ◽  
Author(s):  
Jana Podlahová ◽  
Bohumil Kratochvíl ◽  
Vratislav Langer ◽  
Josef Šilha ◽  
Jaroslav Podlaha
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Structure Determination ◽  
Free Acid ◽  
Hydrogen Bromide ◽  
Carboxyl Groups ◽  
Spectroscopic Methods ◽  
X Ray ◽  
Partial Formation

The equilibria and mechanism of addition of protons to the ethylenediphosphinetetraacetate anion (L4-) were studied in solution by the UV, IR, 1H and 31P NMR spectroscopic methods. A total of six protons can be bonded to the anion. They are added stepwise, first with partial formation of zwitterions containing P-H bonds, which then dissociate with formation of the free acid, H4L, where all four protons are bonded in carboxyl groups. The formation of zwitterions is strongly dependent on the concentration. In the final stage, the acid bonds two additional protons to form the bis-phosphonium cation, H6L2+. A number of isostructural salts containing this cation, H4L.2 HX (X = Cl, Br, I), have been prepared. The X-ray crystal structure determination of the bromide confirmed the expected arrangement. The bromide crystals are monoclinic, a = 578.2, b = 1 425.0, c = 1 046.7 pm, β = 103.07° with a space group of P21/c, Z = 2. The final R factor was 0.059 based on 1 109 observed reflections. The structure consists of H6L2+ cations containing protons bonded to phosphorus atoms (P-H distance 134 pm) and of bromide anions, located in gaps which are also sufficiently large for I- anions in the isostructural iodide. The interbonding of phosphonium cations proceeds through hydrogen bonds, C-OH...O=C, in which the O...O distance is 275.3 pm.

scholarly journals Radical Ion Salts and Complexes, Part XVII. TCNQ Salts of 1,4-Dimethylpyridine and 2,3-Bis(1-methyl-4-pyridinio)butane

1999 ◽  
Vol 23 (3) ◽  
pp. 196-197
Author(s):  
Timothy J. Houghton ◽  
Stephen C. Wallwork
Keyword(s):  
Structure Determination ◽  
X Ray ◽  
Electrical Conductivities ◽  
Complex Salts ◽  
Radical Ion Salts

X-Ray structure determination of the complex salts [MeNC5H4Me]+[TCNQ2]- [1,4-dimethylpyridinium 2(7,7,8,8-tetracyanoquinodimethane) (1-); I] and [Me(NC5H4)(Me)CH-CH(Me)(C5H4N)Me]2+[TCNQ4]2- [ meso-2,3-bis( N-methyl-4-pyridyl)butane(2+) 4(7,7,8,8-tetracyanoquinodimethane) (2-); II], where TCNQ=(CN)2C(C6H4)C(CN)2, shows that, although in both salts the TCNQ moieties are stacked in columns, lateral shifts break these columns into diads for I and tetrads for II causing their electrical conductivities to be only moderate (Σ = 2–4 × 10−3 ohm−1 cm−1).

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