A novel carbonyl bridging mode: the structure of the metal carbonyl complex [Mn2(CO)5(Ph2PCH2PPh2)2]

1975 ◽  
Vol 28 (8) ◽  
pp. 1663 ◽  
Author(s):  
CJ Commons ◽  
BF Hoskins
Keyword(s):  
Least Squares Method ◽  
Metal Carbonyl ◽  
Three Dimensional ◽  
Carbonyl Complex ◽  
X Ray Diffraction ◽  
Carbonyl Ligand ◽  
Fourier Methods ◽  
X Ray ◽  
Carbonyl Bond ◽  
Temperature Factors

The crystal structure of the solvated complex Mn2(CO)5(dpm)2,CH2Cl3,C6H14 (where dpm = Ph2PCH2PPh2) has been determined by three-dimensional X-ray diffraction methods. The crystals are monoclinic, of space group Cc, with a 19.650(3), b 16.908(2), c 22.253(4) Ǻ and β 130.89(1)�, containing four molecules per unit cell. The structure, solved by conventional Patterson and Fourier methods, was refined by a least- squares method, using individual isotropic temperature factors, to R and Rw of 0.105 and 0.125 respectively, for 1893 independent statistically significant reflections collected by counter methods. The crystals are molecular, being composed of discrete molecules of complex and solvent. The principal feature of interest in the binuclear manganese complex is the presence of a carbonyl ligand simultaneously bonded to both manganese atoms in a manner quite different from the normal symmetrical bridging mode. This novel arrangement, which seems to involve a metal-carbonyl bond analogous to that found for many metal-olefin complexes, accounts for the anomalously low carbonyl stretching frequency observed at 1645 cm-1. The Mn-Mn distance is 2.934(6) Ǻ.

The crystal structure of tetraethylammonium Tris(O-ethylxanthato)tellurate(II): An example of five-coordinate pentagonal-planar geometry

1976 ◽  
Vol 29 (11) ◽  
pp. 2337 ◽  
Author(s):  
BF Hoskins ◽  
CD Pannan
Keyword(s):  
Crystal Structure ◽  
Least Squares Method ◽  
Three Dimensional ◽  
Planar Geometry ◽  
Maximum Deviation ◽  
Valence Shell ◽  
X Ray Diffraction ◽  
Electron Pairs ◽  
Fourier Methods ◽  
X Ray

The crystal structure of tetraethylammonium tris(O-ethylxanthato) tellurate(11), [Et4N] [Te(S2COEt)3], has been determined by single-crystal three-dimensional X-ray diffraction methods. Crystals are monoclinic of space group P21/c with four cation-anion pairs per unit cell which has the dimensions a 8.121(1), b 18.858(2), c 19.260(2) � and β 105.22(2)�. The structure was solved by the normal Fourier methods and was refined with anisotropic thermal parameters by a full-matrix least-squares method converging with R and Rw values of 0.061 and 0.082 for the 2404 independent statistically significant reflections collected by counter methods. The tris(ethylxanthato)tellurate(11) anion has a novel five-coordinate pentagonal-planar structure with only two of the xanthato ligands bidentate and with the Te-S bond distances having values in the range 2.503(4)-3.059(3)�. The TeS5 atoms are coplanar, the maximum deviation from the plane being 0.122 �. This, together with the intra-planar S...S distances of 3.340-3.661 �, indicates that the ligand atoms of the pentagonal plane are not over-crowded. The geometry of the anion configuration can be explained in terms of the VSEPR theory using a pentagonal-bipyramidal arrangement of the seven electron pairs in the valence shell of the tellurium.

Complexes of the dicyclohexylphosphinodithioformate anion involving the nickel triad metals: the crystal and molecular structures of the platinum(II) and palladium(II) derivatives

1984 ◽  
Vol 37 (1) ◽  
pp. 197 ◽  
Author(s):  
D Dakternieks ◽  
BF Hoskins ◽  
ERT Tiekink
Keyword(s):  
Phosphorus Atom ◽  
Least Squares Method ◽  
Central Atom ◽  
Three Dimensional ◽  
Molecular Structures ◽  
X Ray Diffraction ◽  
Fourier Methods ◽  
Full Matrix ◽  
X Ray ◽  
Crystal And Molecular Structures

The crystal and molecular structures of bis (dicyclohexylphosphinodithioformato-S,P)M, M[S2CP-(C6Hl1)2]2 where M = Pt (1) and Pd (2), have been determined by single-crystal three-dimensional X-ray diffraction methods. The isomorphous crystals are monoclinic, of space group P21/c with four molecules per unit cell which has dimensions for (1) a 14.732(4), b 15.11 8(4), c 16.000(3) � and β 120.90(2)� and for (2) a 14.721(2), b 15.142(2), c 15.986(2) � and β 120.80(1)�. The structures were solved by normal Fourier methods and were refined with anisotropic thermal parameters. A full-matrix least-squares method was used, involving 3454 and 5052 statistically significant reflections for (1) and (2) respectively with final R and Rw values of 0.058 and 0.055 for (1) and 0.038 and 0.039 for (2). The complexes are isostructural. The ligand coordinates in a bidentate manner to the central atom through the phosphorus atom and one of the sulfur atoms with the metal atom in a cis-planar environment.

A REFINEMENT OF THE CRYSTAL STRUCTURES OF (NH4)2TeBr6 AND Cs2TeBr6

1966 ◽  
Vol 44 (8) ◽  
pp. 939-943 ◽  
Author(s):  
A. K. Das ◽  
I. D. Brown
Keyword(s):  
Least Squares ◽  
Crystal Structures ◽  
Diffraction Data ◽  
Bromine Atom ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
X Ray ◽  
Anisotropic Temperature ◽  
Temperature Factors

(NH4)2TeBr6 and Cs2TeBr6 crystals have the cubic K2PtCl6 structure with space group: [Formula: see text] with a0 = 10.728 ± 0.003 Å and 10.918 ± 0.002 Å respectively. The positional coordinate of the bromine atom, and the anisotropic temperature factors of all atoms in the unit cell, have been refined for both crystals by a full matrix least-squares analysis of the three dimensional X-ray diffraction data (R = 0.08). The Te—Br distance, corrected for probable thermal motions of atoms forming the bond, is 2.70 ± 0.01 Å in both crystals.

The crystal and molecular stucture of μ-Bis(diphenylarsino)methanehexacarbonyldi-μ-chloro-dirhenium(I)-n-hexane (4/1)

1975 ◽  
Vol 28 (6) ◽  
pp. 1201 ◽  
Author(s):  
CJ Commons ◽  
BF Hoskins
Keyword(s):  
Least Squares Method ◽  
Crystal And Molecular Structure ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Rhenium Atom ◽  
X Ray ◽  
Carbonyl Ligands ◽  
Rhenium Complex ◽  
Metal Atoms ◽  
A Site

The crystal and molecular structure of the n-hexane solvate of μ- bis(diphenylarsino)methane-hexacarbonyldi-μ-chloro-dirhenium(I), Re2(CO)6(Ph2AsCH2AsPh2)Cl2, has been determined by three-dimensional X-ray diffraction methods. The complex crystallizes in the space group Pī with a 15.763(1), b 19.077(1), c 12.233(1) Ǻ and α 88.745(10), β 110.506(5), γ 92.900(6)�. The structure was solved by conventional Patterson and Fourier methods and refined by a block-diagonal least- squares method to R and Rw of 0.045 and 0.054, respectively, for 7061 independent statistically significant reflections collected by counter methods. The crystal consists of discrete molecules of the complex and n-hexane held together by van der Waals forces. There are two molecules of the dirhenium complex in the crystallographic asymmetric unit with the n-hexane molecule situated about a site of symmetry ī. The binuclear rhenium complex contains bridging halogen atoms and a bridging diarsine ligand. Three carbonyl ligands are also bonded to each rhenium atom, giving the metal atoms approximately octahedral environments. The average Re-As, Re-Cl, and Re-C bond lengths are 2.58, 2.52, and 1.89 Ǻ respectively.

An X-Ray Crystallographic Study of Cd[P(C-C6H11)3]2(NO3)2.CH2Cl2

1986 ◽  
Vol 39 (4) ◽  
pp. 713 ◽  
Author(s):  
D Dakternieks ◽  
BF Hoskins ◽  
CL Rolls ◽  
ERT Tiekink
Keyword(s):  
Molecular Structure ◽  
Crystal And Molecular Structure ◽  
Three Dimensional ◽  
Cadmium Atom ◽  
X Ray Diffraction ◽  
Fourier Methods ◽  
Full Matrix ◽  
X Ray ◽  
Crystallographic Study ◽  
Tetrahedral Environment

The crystal and molecular structure of bis ( tricyclohexylphosphine )cadmium(II) nitrate as its dichloromethane solvate, Cd [P(c-C6H11)3]2(NO3)2.CH2Cl2, has been determined by single- crystal, three-dimensional X-ray diffraction methods. The crystals of the cadmium(II) complex are monoclinic with space group C2/c, a 20.880(6), b 12.775(3), c 17.075(5) Ǻ and β 106.38(2)°, Z 4. The structure was solved by normal Fourier methods and refined by a full-matrix least-squares procedure. The refinement used the 2169 statistically independent reflections for which I ≥ 2σ(I) converged with R and Rw of 0.065 and 0.067 respectively. The crystals consist of discrete Cd [P(c-C6H11)3]2(NO3)2 molecules and CH2Cl2 in the ratio 1 : 1. There is a distorted tetrahedral environment around the cadmium atom formed from the coordination of the two phosphines and two nitrates with each nitrate essentially occupying one stereochemical position. The two markedly different Cd -O bond lengths of 2.405(9) and 2.575(8) Ǻ show gross asymmetry in the coordination of the nitrate.

The crystal structure of diethylene tetraxanthogen, the oxidation product of the diethylene dixanthate ion

1974 ◽  
Vol 27 (1) ◽  
pp. 27
Author(s):  
BF Hoskins ◽  
MR Hunt
Keyword(s):  
Oxidation Product ◽  
Least Squares Method ◽  
Ring Structure ◽  
The Novel ◽  
X Ray Diffraction ◽  
Fourier Methods ◽  
X Ray ◽  
Disulphide Bonds ◽  
A Site ◽  
Short Carbon

The structure of the oxidation product of the diethylene dixanthate anion, diethylene tetraxanthogen (Cl12H1606S8), has been determined by single crystal X-ray diffraction methods. The crystals are tetragonal of space group Z41/acd with a 15.798(1), c 17.755(1) �, containing eight molecules per unit cell. The structure was solved using conventional Patterson and Fourier methods and refined by a full-matrix least-squares method to R 0.055 for the 817 independent statistically significant reflections collected by counter methods. The crystals are composed of discrete molecules held together by van der Waals forces. Each molecule, situated about a site of symmetry 222, has the novel 22-membered ring structure involving disulphide bonds of length 2.035(2) �. The planarity of the dithiocarbonate moiety and the relatively short carbon-to-oxygen and carbon-to-sulphur bond lengths correlate with extensive π-electron delocalization over the group.

scholarly journals X-ray diffraction studies of enkephalins. Crystal structure of [(4′-bromo) Phe4,Leu5]enkephalin

1984 ◽  
Vol 218 (3) ◽  
pp. 677-689 ◽  
Author(s):  
T Ishida ◽  
M Kenmotsu ◽  
Y Mino ◽  
M Inoue ◽  
T Fujiwara ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Least Squares Method ◽  
Heavy Atom ◽  
Three Dimensional ◽  
Diffraction Method ◽  
Biologically Active ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Relationship Of

In order to investigate the structure-activity relationship of [Leu5]- and [Met5]enkephalins, [(4′-bromo)Phe4, Leu5]-, [(4′-bromo)Phe4, Met5]- and [Met5] enkephalins were synthesized and crystallized. The crystal structure of [(4′-bromo) Phe4, Leu5]- enkephalin was determined by X-ray diffraction method using the heavy atom method and refined to R = 0.092 by the least-squares method. The molecule in this crystal took essentially the same type I' beta-turn conformation found in [Leu5]enkephalin [Smith & Griffin (1978) Science 199, 1214-1216). On the other hand, the preliminary three-dimensional Patterson analyses showed that the most probable conformations of [(4′-bromo)Phe4,Met5]- and [Met5]enkephalins are both the dimeric extended forms. Based on these insights, the biologically active conformation of enkephalin was discussed in relation to the mu- and delta-receptors.

Crystal structure of praseodymium sulphate octahydrate

1981 ◽  
Vol 155 (3-4) ◽  
Author(s):  
I. S. Ahmed Farag ◽  
M. A. El-Kordy ◽  
N. A. Ahmed
Keyword(s):  
Crystal Structure ◽  
Least Squares Method ◽  
Three Dimensional ◽  
The Other ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
Bridging Ligand ◽  
Dimensional Network ◽  
Anisotropic Temperature ◽  
Temperature Factors

AbstractThe crystals of PrThe crystal structure has been determined from three-dimensional single-crystal X-ray diffraction data and refined by the least-squares method, using anisotropic temperature factors, to a discrepancy index ofThe molecules are arranged in layers forming a three-dimensional network. Each Pr atom is coordinated with eight oxygen atoms, four of which are related to sulphate groups, the other four are to water molecules. The sulphate ion, located at the twofold axis, behaves as a bidentate bridging ligand connecting two Pr atoms. The other sulphate ion acts as a threefold bridging ligand between three neighbouring Pr atoms.

Crystal and molecular structure of Octacarbonylbis(diphenylarsino)-methanedimanganese(0)

1983 ◽  
Vol 36 (4) ◽  
pp. 683 ◽  
Author(s):  
BF Hoskins ◽  
RJ Steen
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Least Squares ◽  
Crystal And Molecular Structure ◽  
Parent Compound ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
Fourier Methods ◽  
X Ray

The crystal structure of the complex Mn2(CO)8(dam) (dam = Ph2AsCH2AsPh2) has been determined by three-dimensional X-ray diffraction methods. The crystals are triclinic, space group P1, with a 11.191(1), b 16.498(5), c 9.455(1) �, a 93.64(2), β 109.08(2), γ 89.36(2)� and contain two discrete, binuclear molecules of Mn2(CO)8(dam) per unit cell. The structure, solved by direct and Fourier methods, was refined by a least-squares procedure to R and Rw of 0.065 and 0.082 respectively for 1907 independent, statistically significant reflections collected by counter methods. The feature of particular interest in this compound is the accommodation of the bridging bidentate dam ligand [As.. .As separation 3.242(2) �] across a shorter Mn�-Mn� bond [2.962(3) �] which constrains the molecule so that a much less staggered configuration of the two manganese coordination octahedra is observed relative to the parent compound Mn2(CO)10, the rotation of the two equatorial planes in the former being 30�.

PCl bond length depression upon coordination of a diazaphosphasiletidine to a group 13 element Lewis acid or a transition metal carbonyl fragment – Synthesis and structural characterization of diazaphosphasiletidine adducts with P-coordination

2017 ◽  
Vol 72 (11) ◽  
pp. 873-882 ◽  
Author(s):  
Hülya Gün ◽  
Claudia Mettlach née Casel ◽  
Walter Frank
Keyword(s):  
Bond Length ◽  
Lewis Acid ◽  
Computational Study ◽  
Metal Carbonyl ◽  
Carbonyl Complex ◽  
X Ray Diffraction ◽  
Group 13 ◽  
X Ray ◽  
New Compounds

AbstractThreeP-chloro-substituted diazaphosphasiletidines, Me2Si(NtBu)2PCl (1) and Me2Si(NtBu)2P(E)Cl (E=BCl3(2); W(CO)5(3)), are presented for comparison.1was first prepared more than 30 years ago and studied by means of spectroscopic methods, however, no crystal structure has been reported until now. In the presence of the comparatively weak Lewis acid BCl3and the labile metal carbonyl complex [W(CO)5(THF)],1can be easily converted into its corresponding adducts2and3. All products were characterized by single-crystal X-ray diffraction studies. The structures of the new compounds2and3reveal a remarkable P–Cl bond contraction caused by the coordination of1to the Lewis acid or the Lewis acidic W(CO)5fragment. Although the coordination number of the P atom is increased in2and3, the P–Cl bond length is reduced dramatically, some kind of bond length paradoxon. A computational study suggests that these P–Cl bond shortenings result from a less effective donation of electron density from the lone pairs at the nitrogen atoms to the antibondingσ*(P–Cl) orbital in2and3as compared to1.

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