Synthesis, structure, and solution dynamics of indenyl rhodium complexes containing bulky phosphine ligands: molecular structures of (η5-1-CH3-C9H6)Rh(η2-C2H4)(PCy3) (Cy = cyclohexyl) and (η5-1-CH3-C9H6)Rh(dcpe) (dcpe = Cy2PCH2CH2PCy2)

1999 ◽  
Vol 77 (2) ◽  
pp. 205-215
Author(s):  
Stephen A Westcott ◽  
Ashok K Kakkar ◽  
Nicholas J Taylor ◽  
D Christopher Roe ◽  
Todd B Marder
Keyword(s):  
Variable Temperature ◽  
Unit Cell ◽  
Phosphine Ligands ◽  
Molecular Structures ◽  
H Nmr ◽  
Ring Rotation ◽  
Cell Dimensions ◽  
Solution Dynamics ◽  
High Yields ◽  
Unit Cell Dimensions

Reactions of (η5-1-CH3-C9H6)Rh(η2-C2H4)2 with PCy3 (Cy = cyclohexyl) and 1,2-bis(dicyclohexylphos - phino)ethane (dcpe = Cy2PCH2CH2PCy2) gave complexes (η5-1-CH3-C9H6)Rh(η2-C2H4)(PCy3) (1) and (η5-1-CH3-C9H6)Rh(dcpe) (2), respectively, in high yields. Complexes 1 and 2 were characterized by x-ray diffraction studies and by multinuclear NMR spectroscopy. Variable temperature 31P{1H} NMR spectra allowed for evaluation of energy barriers associated with indenyl ring rotation. While 1 and 2 displayed similar degrees of slip-fold distortion with respect to bonding of the indenyl ligand to the RhL2 fragment, a lower energy barrier to ring rotation was calculated for the mixed ethylene-phosphine complex 1. Yellow crystals of 1 are orthorhombic, Pbca with 16 molecules per unit cell of dimensions a = 11.341(3), b = 32.915(10), and c = 29.413(9) Å. Yellow crystals of 2 are triclinic, P1 with two molecules per unit cell dimensions a = 9.327(3), b = 10.117(3), c = 18.934(6) Å, α = 104.28(2)°, β = 101.34(2)°, and γ = 92.99(2)°.Key words: indenyl, rhodium, phosphines, ring-slippage.

scholarly journals Synthesis And Structural Characterization Of 1-Butyl-2,3-Dimethylimidazolium Bromide And Iodide

2007 ◽  
Vol 62 (6) ◽  
pp. 868-870 ◽  
Author(s):  
Johanna Kutuniva ◽  
Raija Oilunkaniemi ◽  
Risto S. Laitinen ◽  
Janne Asikkala ◽  
Johanna Kärkkäinen ◽  
...  
Keyword(s):  
Unit Cell ◽  
Monoclinic Crystal System ◽  
Monoclinic Crystal ◽  
Space Group ◽  
X Ray ◽  
Crystal System ◽  
H Nmr ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

1-Butyl-2,3-dimethylimidazolium bromide {(bdmim)Br} (1) and iodide {(bdmim)I} (2) were prepared conveniently by the reaction of 1,2-dimethylimidazole and the corresponding 1-halobutane. The compounds were characterized by 1H and 13C{1H} NMR spectroscopy as well as by X-ray single crystal crystallography. 1 crystallizes in the monoclinic crystal system, space group P21/n, with Z = 4, and unit cell dimensions a = 8.588(2), b = 11.789(1), c = 10.737(2) Å, β = 91.62(3)°. Compound 2 crystallizes in the monoclinic crystal system, space group P21/c, with Z = 8, and unit cell dimensions a = 10.821(2), b = 14.221(3), c = 15.079(2) Å , β = 90.01(3)°. The lattices of the salts are built up of 1-butyl-2,3- dimethylimidazolium cations and halide anions. The cations of 1 form a double layer with the imidazolium rings stacked together due to π interactions. The Br− anions lie approximately in the plane of the imidazolium ring, and the closest interionic Br···H contacts span a range of 2.733(1) - 2.903(1) Å. Compound 2 shows no π stacking interactions. The closest interionic I···H contacts are 2.914(1) - 3.196(1) Å

scholarly journals Comparison of the C—H...O bonding in two crystalline phases of 1,4-dithiane 1,1,4,4-tetraoxide

2019 ◽  
Vol 75 (5) ◽  
pp. 576-579
Author(s):  
Richard L. Harlow ◽  
Allen G. Oliver ◽  
Jonathan M. Baker ◽  
William J. Marshall ◽  
Michael P. Sammes
Keyword(s):  
Hydrogen Bonds ◽  
Phase 1 ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Nmr Spectrum ◽  
Crystalline Phases ◽  
Space Group ◽  
H Nmr ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

The crystal structures of two crystalline phases of 1,4-dithiane 1,1,4,4-tetraoxide, C4H8O4S2, have been determined in order to examine the nature of possible intermolecular hydrogen bonds. Phase 1 is monoclinic, space group C2/m, with unit-cell dimensions of a = 9.073 (8), b = 7.077 (6), c = 5.597 (5) Å and β = 105.89 (1)°. The molecule adopts 2/m symmetry and all of the molecules are related by translation and thus have the same orientation. Phase 2 is also monoclinic but in space group P21/n with unit-cell dimensions of a = 7.1305 (5), b = 5.7245 (4), c = 8.3760 (6) Å and β = 91.138 (2)°. In this phase, the molecule sits on an inversion center and the molecules within the unit cell adopt quite different orientations. In both phases, examination of the potential C—H...O hydrogen bonds around each of the independent oxygen atoms (one axial and the other equatorial) shows the general O...H patterns to be quite similar with each oxygen atom in contact with four neighboring H atoms, and each H atom contacting two neighboring O atoms. While none of the H...O contacts is particularly short (all are greater than 2.5 Å), each molecule has 32 such contacts that form an extensive intermolecular network. A 1H NMR spectrum of the compound dissolved in DMSO shows a singlet of 8H at δ 3.677 which indicates that the C—H bonds are only moderately polarized by the single adjacent –SO2– moiety: strongly polarized C—H bonds have δ values in the 5–6 range [Li & Sammes (1983). J. Chem. Soc. Perkin Trans. 1, pp. 1303–1309]. The phase 1 crystal studied was non-merohedrally twinned.

The External Shape of Human γ GI Immunoglobulin from Crystal Sections

1971 ◽  
Vol 29 ◽  
pp. 428-429
Author(s):  
L. W. Labaw
Keyword(s):  
Molecular Weight ◽  
Sodium Phosphate ◽  
Osmium Tetroxide ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
X Ray ◽  
Large Molecular Weight ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Crystallographic Axes

Crystals of a human γGl immunoglobulin have the external morphology of diamond shaped prisms. X-ray studies have shown them to be monoclinic, space group C2, with 2 molecules per unit cell. The unit cell dimensions are a = 194.1, b = 91.7, c = 51.6Å, 8 = 102°. The relatively large molecular weight of 151,000 and these unit cell dimensions made this a promising crystal to study in the EM.Crystals similar to those used in the x-ray studies were fixed at 5°C for three weeks in a solution of mother liquor containing 5 x 10-5M sodium phosphate, pH 7.0, and 0.03% glutaraldehyde. They were postfixed with 1% osmium tetroxide for 15 min. and embedded in Maraglas the usual way. Sections were cut perpendicular to the three crystallographic axes. Such a section cut with its plane perpendicular to the z direction is shown in Fig. 1.This projection of the crystal in the z direction shows periodicities in at least four different directions but these are only seen clearly by sighting obliquely along the micrograph.

The influence of pH on the synthesis of mixed Fe-Mn oxide minerals

Clay Minerals ◽  
1990 ◽  
Vol 25 (4) ◽  
pp. 507-518 ◽  
Author(s):  
M. H. Ebinger ◽  
D. G. Schulze
Keyword(s):  
Iron Oxides ◽  
Mole Fraction ◽  
Unit Cell ◽  
Mn Oxide ◽  
Cell Dimensions ◽  
The Mean ◽  
Mn Substitution ◽  
Oxide Minerals ◽  
Unit Cell Dimensions ◽  
Influence Of Ph

AbstractMn-substituted iron oxides were synthesized at pH 4, 6, 8, and 10 from Fe-Mn systems with Mn mole fractions (Mn/(Mn + Fe)) of 0, 0·2, 0·4, 0·6, 0·8, and 1·0, and kept at 50°C for 40 days. The Mn mole fraction in goethite was <0·07 at pH 4 but increased to ∼0.47 at pH 6. Goethite and/or hematite formed in Fe and Fe + Mn syntheses at pH 4 and pH 6 at Mn mole fractions ≤0·8, and at Mn mole fractions ≤0·2 at pH 8 and pH 10. Hausmannite and jacobsite formed at pH 8 and pH 10 at Mn mole fractions ≥0·4. In the pure Mn syntheses, manganite (γ-MnOOH) formed at pH 4 and pH 6, whereas hausmannite (Mn3O4) formed at pH 8 and pH 10. As the Mn substitution increased, the unit-cell dimensions of goethite shifted toward those of groutite, and the mean crystallite dimensions of goethite decreased.

Structural studies on crystals found in the intestine of Nematodirus battus

1980 ◽  
Vol 208 (1173) ◽  
pp. 409-414
Keyword(s):  
Electron Microscopy ◽  
Unit Cell ◽  
Structural Studies ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

Crystals found in the lumen of the intestine of Nematodirus battus have been studied by electron microscopy. Two of the unit cell dimensions are 16 nm x 23 nm. The possibility of an immunological significance for these crystals is considered.

Crystallization of Helix pomatia agglutinin (HPA), a protein from the edible snail

1999 ◽  
Vol 55 (11) ◽  
pp. 1903-1905 ◽  
Author(s):  
John N. Lisgarten ◽  
James E. Pitts ◽  
Rex A. Palmer ◽  
Colin D. Reynolds ◽  
Minh Hoa Dao-Thi ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Diffraction Pattern ◽  
Helix Pomatia ◽  
Unit Cell ◽  
Hanging Drop ◽  
Helix Pomatia Agglutinin ◽  
Cell Dimensions ◽  
Protein Molecules ◽  
Unit Cell Dimensions ◽  
Drop Technique

Crystals of Helix pomatia agglutinin (HPA) have been grown by the hanging-drop technique using polyethylene glycol as the precipitant at 293 K. Over a period of one to two weeks the crystals grew to maximum dimensions of 0.10 × 0.05 × 0.02 mm. The crystals belong to space group P6322, with unit-cell dimensions a = b = 63.3, c = 105.2 Å and Z = 12 identical monomers of Mr = 13 kDa, aggregating into two 78 kDa hexameric protein molecules per unit cell, each with symmetry 32 (D 3). The diffraction pattern extends to 3.6 Å at 293 K.

scholarly journals Unit cell dimensions of some synthetic olivine group solid solutions

1968 ◽  
Vol 2 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Yoshito Matsui ◽  
Yasuhiko Syono
Keyword(s):  
Solid Solutions ◽  
Unit Cell ◽  
Cell Dimensions ◽  
Unit Cell Dimensions
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