Structure cristalline et moléculaire du cyclopentadiényle dicarbonyle dioxyde de soufre manganèse MnC5H5(CO)2SO2

1973 ◽  
Vol 51 (22) ◽  
pp. 3684-3689 ◽  
Author(s):  
Claude Barbeau ◽  
Ram Janam Dubey
Keyword(s):  
Least Squares ◽  
Average Distance ◽  
Unit Cell ◽  
Monoclinic System ◽  
Full Matrix ◽  
Space Group ◽  
Cyclopentadienyl Complexes ◽  
Distance Formula

The compound MnC5H5(CO)2SO2 crystallizes in the monoclinic system, space group P21/c, in a unit cell of dimensions a = 10.98(2) Å, b = 10.63(2) Å, c = 7.43(2) Å, β = 100.75(8)° with Z = 4. The structure was determined from 1512 reflections obtained on films from a precession camera; the residual factor, R, was 0.093 after a full matrix least-squares refinement. The Mn–S bond seems very strong having a length (2.037(5) Å) which is smaller than the sum of the covalent radii by 0.3 Å The average distance [Formula: see text] is less than that usually observed in manganese–cyclopentadienyl complexes. The two CO groups are distinct. The instability of the complex might be explained, in part, by the crowding of the SO2 and CO ligands. [Journal translation]

Dinuclear cobalt(II) complexes of a polyhydroimidazole ligand. Dinuclear (2:1) non-metallocyclic derivatives and dinuclear (1:1) metallocyclic complexes with a large, unoccupied central cavity

1992 ◽  
Vol 70 (11) ◽  
pp. 2771-2776 ◽  
Author(s):  
Santokh S. Tandon ◽  
Laurence K. Thompson ◽  
John N. Bridson ◽  
John C. Dewan
Keyword(s):  
Least Squares ◽  
Bidentate Ligand ◽  
Unit Cell ◽  
Molecular Structures ◽  
Central Cavity ◽  
Monoclinic System ◽  
Full Matrix ◽  
Space Group ◽  
Cell Refinement ◽  
Compound Ii

The ligand BTIM (1,2,4,5-tetrakis(4,5-dihydro-imidazol-2-yl)benzene) reacts with cobalt(II) salts to form two series of complexes. The 1:1, dinuclear, metallocyclic derivatives [Co2(BTIM)2X2]X2 (X = Cl (I), Br (II)) involve two bis-dentate ligands in a metallocyclic structure with a large unoccupied cavity. The 2:1, binuclear derivatives [Co2(BTIM)X4] (X = Cl (III), Br (IV)) involve two metals bound to a single, bis-bidentate ligand. The crystal and molecular structures of II and III are reported. Compound II crystallized in the monoclinic system, space group P21/c, with a = 13.642(6) Å, b = 11.560(3) Å, c = 18.406(7) Å, β = 101.73(3)° and four formula units per unit cell. Refinement by full-matrix least squares gave final residuals of R = 0.060 and Rw = 0.062. Compound III crystallized in the triclinic system, space group [Formula: see text], with a = 8.367(2) Å, b = 14.254(3) Å, c = 7.649(2) Å, α = 100.99(2)°, β = 101.44(2)°, γ = 106.85(1)° and one formula per unit cell. Refinement by full-matrix least squares gave final residuals of R = 0.052 and Rw = 0.045. In the metallocyclic structure (II) the square-pyramidal cobalt(II) centres are separated by 7.599(4) Å, while in the 2:1 derivative the two tetrahedral cobalt(II) centres have a much larger separation (8.736(3) Å).

Refinement of the structure of Mg2As2O7

1970 ◽  
Vol 48 (6) ◽  
pp. 890-894 ◽  
Author(s):  
C. Calvo ◽  
K. Neelakantan
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Least Squares ◽  
Unit Cell ◽  
Full Matrix ◽  
Space Group ◽  
Cell Dimensions ◽  
Central Oxygen ◽  
R Value ◽  
Unit Cell Dimensions

The crystal structure of Mg2As2O7 has been refined by full matrix least squares procedures using 587 observed reflections. The structure of Mg2As2O7 is of the thortveitite type, as reported by Łukaszewicz, with space group C2/m and unit cell dimensions a = 6.567(2) Å, b = 8.524(4) Å, c = 4.739(1) Å, β = 103.8(1)°, and Z = 2. The As—O—As group in the anion appears to be linear but the central oxygen atom undergoes considerable disorder in the plane perpendicular to this group. The AsO bond distances uncorrected for thermal motion are 1.67 Å for the As—O(—As) bond and 1.66 and 1.65 Å for the terminal As—O bonds. The final R value obtained is 0.088.

Refinement of the Crystal Structure of the Low-quartz Modification of Ferric Phosphate

1975 ◽  
Vol 53 (14) ◽  
pp. 2064-2067 ◽  
Author(s):  
Hok Nam Ng ◽  
Crispin Calvo
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Room Temperature ◽  
Unit Cell ◽  
Full Matrix ◽  
Space Group ◽  
Ferric Phosphate ◽  
R Value

The structure of ferric phosphate at room temperature was refined on a Dauphiné-twinned crystal using full-matrix least-squares methods. The final R value was 0.078 for 487 symmetry-independent reflections whose intensities were corrected for twinning. The structure was found to be isotypic with AlPO4 (berlinite) with the space group P3121 and four formula units in a unit cell defined by a = 5.036(2) and c = 11.255(4) Å. The structure is also closely related to that of α-quartz with a nearly doubled c-axis because of the ordering of Fe and P atoms. The PO4 tetrahedron is almost regular with a mean P—O distance of 1.526 Å. The Fe3+ ion is tetrahedrally coordinated with an average Fe—O distance of 1.853 Å.

Refinement of the Crystal Structure of Synthetic Chervetite, Pb2V2O7

1973 ◽  
Vol 51 (1) ◽  
pp. 70-76 ◽  
Author(s):  
Robert D. Shannon ◽  
Crispin Calvo
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Unit Cell ◽  
Type Structure ◽  
Covalent Bonds ◽  
Full Matrix ◽  
Space Group ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

The structure of synthetic chervetite has been refined by full matrix least-squares to a ωR = 0.029 using 1105 reflections. Unit cell dimensions are a = 13.3689(7), b = 7.1607(4), c = 7.1027(4) Å, β = 105935(5)°, and the space group is P21/a. The structure, originally solved by Kawahara, is a dichromate-type structure with a V2O74− group eclipsed to within 11 ± 5°. The Pb2+ ions are irregularly coordinated to 8 or 9 oxygens with distances from 2.40 to 3.20 Å. The distortion of the Pb–O distances is considerably greater than the corresponding distortions of the Sr–O distances in the similar β-Sr2V2O7 structure and is related to the tendency of Pb2+ to form directional covalent bonds. The V–O distances range from 1,665 to 1.720 Å for terminal oxygens and are 1.812 and 1.821 Å for the bridging oxygens. The V–O distances are consistent with the strengths of the Pb—O bonds.

Structure cristalline et moléculaire du cyclopentadiényle-carbonyle-bistriphénylphosphine-manganèse (benzénate), MnC5H5CO[P(C6H5)3]2•C6H6

1974 ◽  
Vol 52 (7) ◽  
pp. 1140-1146 ◽  
Author(s):  
Claude Barbeau ◽  
Ram Janam Dubey
Keyword(s):  
Molecular Structure ◽  
Least Squares ◽  
Crystal And Molecular Structure ◽  
Three Dimensional ◽  
Unit Cell ◽  
Electrostatic Repulsion ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
Distance Formula

The crystal and molecular structure of cyclopentadienylcarbonyl-bis(triphenylphosphine)-manganese(benzenate), MnC5H5CO[P(C6H5)3]2•C6H6, has been obtained from analysis of three dimensional X-ray data obtained with a precession camera. The red, rectangular crystals are triclinic, space group [Formula: see text] and have a unit cell with the following parameters: a = 9.83(2) Å, b = 14.79(1) Å, c = 11.36(2) Å, α = 69.44(8)°, β = 66.48(8)°, γ = 67.57(10)°, and z = 2. The final residual factor is 0.087 for the 4554 independent reflections used in the least squares refinement. The structure consists of individual molecules of Mn(C5H5)CO[P(C6H5)3]2. The distance [Formula: see text] is 2.16(1) Å. The coordinate CO (Mn—C: 1.748(9) Å, C—O: 1.172(11) Å) is perpendicular to the plane of the phosphorous and manganese atoms.The important characteristic is the angle P—Mn—P of 104(1)° (Mn—P: 2.237(3) Å). The angular opening of 14° is considered to be a consequence of an electrostatic repulsion between the two donor P atoms. [Journal translation]

Structure of Nickel Orthophosphate

1975 ◽  
Vol 53 (10) ◽  
pp. 1516-1520 ◽  
Author(s):  
Crispin Calvo ◽  
Romolo Faggiani
Keyword(s):  
Bond Length ◽  
Least Squares ◽  
Monoclinic System ◽  
Full Matrix ◽  
Space Group ◽  
Bond Lengths ◽  
The Mean ◽  
R Value ◽  
Cation Sites

Ni3P2O8 crystallizes in the monoclinic system with space group P21/c with a = 5.830(2), b = 4.700(2), c = 10.107(4) Å, β = 91.22(2)°, and Z = 2. The structure was refined by full-matrix least squares methods to a final R value of 0.035 using 986 symmetry independent reflections. The structure is isotypic with that of sarcopside, which in turn is related to that of olivine with vacant cation sites ordered. The Ni ions are octahedrally coordinated in two types of sites with average Ni—O bond lengths of 2.081 and 2.067 Å. The mean P—O bond length is 1.547 Å although the tetrahedron shows some unusually large distortions with bond lengths ranging from 1.521 to 1.595 Å.

Crystal and molecular structure of dodecamethylcyclohexaphosphazene, (NPMe2)6

1977 ◽  
Vol 55 (17) ◽  
pp. 3118-3123 ◽  
Author(s):  
Richard T. Oakley ◽  
Norman L. Paddock ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Molecular Structure ◽  
Least Squares ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Unit Cell ◽  
Weighted Mean ◽  
Full Matrix ◽  
Space Group ◽  
Bond Lengths ◽  
The Mean

Crystals of dodecamethylcyclohexaphosphazene are triclinic, a = 13.898(1), b = 8.690(1), c = 10.790(1) Å, α = 109.84(1), β = 92.01(1), γ = 106.39(1)°, Z = 2, space group [Formula: see text]. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to a final R of 0.034 and Rw of 0.042 for 4217 reflections with I ≥ 3σ(I). The unit cell contains two independent centrosymmetric molecules which are virtually identical. The 12-membered rings have the 'double tub' conformation. Bond lengths not involving hydrogen have been corrected for libration. Weighted mean bond lengths (rms deviations from the mean in parentheses) are: P—N, 1.593(6), C—P, 1.808(4), and C—H, 0.95(6) Å.

Studies in aryltin chemistry. Part 6. Crystal and molecular structures of tetra(p-methylsulphonylphenyl)tin(IV) and tetra(p-methylsulphinylphenyl)tin(IV) monohydrate

1990 ◽  
Vol 68 (8) ◽  
pp. 1277-1282 ◽  
Author(s):  
Ivor Wharf ◽  
Michel G. Simard ◽  
Henry Lamparski
Keyword(s):  
Least Squares ◽  
Crystal Structures ◽  
Direct Method ◽  
Molecular Structures ◽  
Water Molecules ◽  
Monoclinic Space Group ◽  
Molecular Symmetry ◽  
Asymmetric Unit ◽  
Full Matrix ◽  
Space Group

Tetrakis(p-methylsulphonylphenyl)tin(IV) and tetrakis(p-methylsulphinylphenyl)tin(IV) n-hydrate have been prepared and their spectra (ir 1350–400 cm−1; nmr, 1H, 13C, 119Sn) and X-ray crystal structures are reported. The first compound is monoclinic, space group C2/c, Z = 4, with a = 21.589(6), b = 6.207(3), c = 22.861(11) Å, β = 93.80(3)° (22 °C); the structure was solved by the direct method and refined by full-matrix least squares calculations to R = 0.043 for 2755 observed reflections. It has 2 molecular symmetry with the methyl group and one oxygen atom completely disordered in both CH3S(O2) groups in the asymmetric unit. The second compound is tetragonal, space group P42/n, Z = 2, with a = b = 15.408(6), c = 6.379(2) Å (−100 °C); the structure was solved by the Patterson method and refined by full-matrix least squares calculations to R = 0.060 for 1209 observed reflections. It has [Formula: see text] molecular symmetry with the whole asymmetric unit disordered. Water molecules occupy positions on parallel 42 axes but molecular packing requirements prevent all sites having 100% occupancy giving n ~ 1 for the hydrate. Keywords: Tetra-aryltins, crystal structures, sulphone, sulphoxide, hydrogen-bonding.

The crystal and molecular structure of 1,1-bis(diphenylphosphino)-2,2-dimethylhydrazine

1976 ◽  
Vol 54 (5) ◽  
pp. 738-743 ◽  
Author(s):  
J. Brian Faught
Keyword(s):  
Molecular Structure ◽  
Least Squares ◽  
Crystal And Molecular Structure ◽  
Unit Cell ◽  
Space Group ◽  
Block Diagonal

The structure of 1,1-bis(diphenylphosphino)-2,2-dimethylhydrazine, [(C6H5)2P]2NN(CH3)2 has been determined crystallographically. The compound crystallizes from n-heptane in the space group P21/c with a = 8.910(1), b = 9.686(1), c = 27.489(4) Å, and β = 102.94(2)° with four molecules per unit cell. The structure was solved from 2669 independent reflections with I > 3σ(I) and refined by block diagonal least squares methods to R = 0.032 and Rω = 0.048. Each diphenylphosphino group is bonded to the same hydrazine nitrogen and the geometry about this nitrogen is nearly planar. The average dimensions of the structure are P—C = 1.828 ± 0.005, P—N = 1.715 ± 0.014, N—N = 1.451, and N—C = 1.457 ± 0.003 Å, [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text].

Structure of the Tris(diallyldithiocarbamate)cobalt(III) Complex

1992 ◽  
Vol 57 (2) ◽  
pp. 332-338 ◽  
Author(s):  
Eleonóra Kellö ◽  
Jan Lokaj ◽  
Viktor Vrábel
Keyword(s):  
Least Squares ◽  
Metal Atom ◽  
Least Squares Method ◽  
Heavy Atom ◽  
Distorted Octahedron ◽  
Monoclinic System ◽  
Space Group ◽  
Twofold Axis ◽  
Diagonal Approximation ◽  
Heavy Atom Method

The structure of [Co{S2CN(CH2-CH=CH2)2}3] was determined by the heavy atom method, all nonhydrogen atoms being refined by anisotropic diagonal approximation using the least squares method to the value of R= 0.067 for 1 024 reflections with I ≥ 1.96σ(I). The substance is isostructural with [Fe{S2CN(CH2-CH=CH2)2}3], crystallizes in the monoclinic system, space group C2/c, lattice parameters a = 1.8763(9), b = 1.0209(5), c = 1.5402(7) nm, β = 106.18(4)°, Z = 4. Cobalt is coordinated by 3 dithiocarbamate ligands in the bidentate way, the average Co-S lenght is 0.2267(2) nm. The metal atom and two ligand atoms are located on the twofold axis. The CoS6 polyhedron is a trigonally distorted octahedron.

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