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1.
M.David Curtis John Greene William M. Butler 《Journal of organometallic chemistry》1979,164(3):371-380
The structure of the cyclo-metalladisiloxane, Me2SiOSiMe2Ir(H)(CO)(PPh3)2, has been determined by single crystal X-ray diffraction using Mo-Kα radiation. Data were collected to 20 = 45 ° giving 6060 unique reflections,of which 4582 had I ?3σ(I). The latter were used in the full-matrix refinement. Crystallographic data: space group, P; cell constants: 12.604(7),12.470(4), 15.821(6) Å, 66.93(6)°, 105.34(7)°, 112.41(8)°;V 2095(3) Å3; p(obs) 1.45 g/cm3; p(calc) 1.46g/cm3 (Z=2). The asymmetric unit consists of one iridium complex and one molecule of ethanol of salvation. The structure was solved by standard heavy atom methods and refined with all non-hydrogen atoms anisotrophic to final R factors, R1 0.034 and R2 0.042. The iridium metallocycle has approximate Cs symmetry with the mirror plane passing through the four-membered IrSiOSi ring. The average IrP, IrSi and SiO bond lengths are 2.38, 2.41, and 1.68 Å, respectively. The IrCO and CO bond lengths are 1.903(8) and 1.133(8). The H atom bonded to Ir was not located.The Ir atom is raised out of the basal, P2Si2 plane toward the carbonyl by about 0.26 Å. The most striking feature of the structure is the strain apparent in the four-membered ring. The internal angels are: 64.7 (SiIrSi), 96.8 (IrSiO), 97.8 (IrSiO), and 99.8 (SiOSi). In an unstrained molecule, the SiOSi angle is normally in the 130–150° range. It is proposed that the strain in the ring is consistent with the catalytic activity of the metallocycle. 相似文献
2.
Catherine J. Hurt Joseph C. Calabrese Robert West 《Journal of organometallic chemistry》1975,91(3):273-278
The crystal structure of [Si(CH3)(t-C4H9)]4 has been determined by single crystal X-ray diffraction. The crystals are tetragonal, P42/n; a = b = 13.069(4), c = 7.880(2) Å, Z = 2. The structure was determined using 745 independent data and refined with anisotropic least-squares to a final unweighted R-value of 3.5%. Each tetrameric molecule was found to be arranged about a axis, with the independent crystallographic unit comprising one silicon atom, one methyl and one tert-butyl group. The four-membered ring of silicon atoms is nonplanar with an unusually large dihedral angle of 36.8°. The principal mean bond lengths are SiSi 2.377(1), SiC(methyl) 1.893(4), SiC(tert-butyl) 1.918(3) Å, and the SiSiSi bond angle is 86.99°. The SiSi bond length is somewhat longer than in other polysilanes. 相似文献
3.
4.
The structure of (Ph3SiN)2C has been determined by single crystal X-ray diffraction. The structure was solved by direct methods and refined to R = 0.071 for 593 independent diffractometer data. The crystals are rhombohedral, R with a = b = c 18.201(20) Å, α = β = γ = 48.82(2)°, and Z = 4. The three crystallographically independent molecules each have linear SiNCNSi chains lying along the crystallographic threefold axes; in two of the molecules the central carbon atom lies on a centre of symmetry. Principal mean bond lengths and angles are: Si, 1.696(25); SiC, 1.846(20); NC, 1.164(30); CC, 1.387(14) Å; CSi, 108.2(6); and CSiC, 110.8(6)°. 相似文献
5.
The electron diffraction data for methyltrimethoxysilane are consistent with a C3 symmetry model, the predominant forms of which have rotational angle(s) between 100 and 155° around the SiO bond (the anti conformation of the CSiOC chain would respond to 0°). There is probably large amplitude motion around the SiO bonds. The following bond lengths and bond angles were determined: ra(CH) 1.093 ± 0.005, ra(SiC) 1.842 ± 0.013, ra(SiO) 1.632 ± 0.004, ra(OC) 1.425 ± 0.004 », ∠CSiO 109.6 ± 0.5°. and ∠SiOC 123.6 ± 0.5°. 相似文献
6.
Rudolf Allmann Wolfgang Henke Peter Krommes Jörg Lorberth 《Journal of organometallic chemistry》1978,162(3):283-287
The molecular and crystal structure of tris(bistrimethylsilylamin)thallium was determined by means of single-crystal X-ray spectroscopy: in the space group P1c with a = 16.447(7), c = 8.456(7) Å; and Dc = 1.149 g cm?3 two molecules are located in the unit cell. The compound is isomorphous to the analogues Fe[N(SiMe3)2]3 or Al[N(SiMe3)2]3, respectively, which show a propellar-twist of the Si2N-groups versus the plane of the metal atom and the three nitrogen-atoms: Tl(N)3/Si2N 49.1°; SiNSi 122.6°; NSiC 111.8°; CSiC 107.1°; TlN 2.089 Å;; SiN 1.738 Å;; 1.889 Å;. 相似文献
7.
Ba2V2O7 is triclinic with a = 13.571(3), b = 7.320(2), c = 7.306(2) Å, α = 90.09(1), β = 99.48(1), β = 99.48(1), γ = 87.32(1)°, V = 7.15.1 Å3, Z = 4, and space group . The crystal structure was solved by Patterson and Fourier methods and refined by full-matrix least-squares analysis to a Rw of 0.034 (R = 0.034) using 2484 reflections measured on a Syntex automatic four-circle diffractometer. The structure has two unique divanadate groups that are repeated by the b and c lattice translations to form sheets of divanadate groups parallel to (100). These sheets are linked by four unique Ba atoms that lie between these sheets. Ba(1) and Ba(3) are coordinated by eight oxygens arranged in a distorted biaugmented triangular prism and a distorted cubic antiprism, respectively. Ba(2) is coordinated by 10 oxygens arranged in a distorted gyroelongated square dipyramid and Ba(4) is coordinated by nine oxygens arranged in a distorted triaugmented triangular prism. These coordination numbers are substantiated by a bond strength analysis of the structure, and the variation in 〈BaO〉 distances is compatible with the assigned cation and anion coordination numbers. Both divanadate groups are in the eclipsed configuraton with 〈VO(br)〉 bond lengths of 1.821(4) and 1.824(4) Å and VO(br)V angles of 125.6(3) and 123.7(3)°, respectively. Examination of the divanadate groups in a series of structures allows certain generalizations to be made. Longer 〈VO(br)〉 bond lengths are generally associated with smaller VO(br)V angles. When VO(br)V < 140°, the divanadate group is generally in an eclipsed configuration; when VO(br)V > 140°, the divanadate group is generally in a staggered configuration. Nontetrahedral cations with large coordination numbers require more oxygens with which to bond, and hence O(br) is more likely to be three coordinate, with the divanadate group in the eclipsed configuration. In the eclipsed configuration, decrease in VO(br)V promotes bonding between O(br) and nontetrahedral cations, and hence smaller nontetrahedral cations are generally associated with smaller VO(br)V angles. 相似文献
8.
Colin Eaborn Peter B. Hitchcock Paul D. Lickiss 《Journal of organometallic chemistry》1981,221(1):13-17
The structure of the crowded molecule (Me3Si)3C(SiMe2Ph) has been determined by single crystal X-ray diffraction. The steric strain manifest itself mainly in lengthening of the Me3SiC and Me2PhSiC bonds (average length 1.920(6) ) and closing up of the CSiC angles within the Me3Si and Me2PhSi groups (average 105.2(10)°), with correspondingly large C(1)SiC angles (113.5(13)°; C(1) is the central carbon atom). 相似文献
9.
O. Glemser 《Journal of fluorine chemistry》1984,24(3):319-325
The structures of the solid fluorides MF2, MF3, MF4 and MF5, in which M has the coordination number 6 and belongs to the 3, 4- and 5-periods and the Vb to VIII groups, can be divided into 3 types: (a) cubic close packing () of F with an MFM bridging angle of 180°; (b) hexagonal close packing () with an MFM-bonding angle of 132°; (c) intermediate packing between (a) and (b). The linear bridging is assumed to be a consequence of π-back bonding (or charge transfer) between F-orbitals and -orbitals of the metal. If such bonding is not possible then with the bridging angle of 132° will result. Weaker π-interactions give the intermediates (c). 相似文献
10.
A.A. Pasynskii Yu.V. Skripkin I.L. Eremenko V.T. Kalinnikov G.G. Aleksandrov V.G. Andrianov Yu.T. Struchkov 《Journal of organometallic chemistry》1979,165(1):49-56
(C5H5)2NbBH4 reacts with C5H5M(CO)3Me in toluene solution in the presence of Et3N to give binuclear complexes (C5H5)2NbM(CO)3C5H5 where M is Mo or W (IV and V, respectively). The structure of IV has been studied by X-ray diffraction (the crystals are orthorhombic, a 12.748(5), b 16.745(6), c 14.314 ;; Z = 8, space group of Pbca, automatic difractometer Syntex P2I, λ(Mo-Kα, 1382 reflections, R = 0.056, Rw = 0.058). Molecule IV contains a wedge-like sandwich (π-C5H5)2Nb (NbC 2.37–2.48, CC (av) 1.42 ;, angle between ring planes 49°) linked with the (π-C5H5)Mo(CO) fragment by a direct NbMo bond (3.073 ;) and two bridging CO groups, one nonsymmetrically bonded through the carbon atom only (CO 1.17, NbC 2.53, MoC 2.02 ;) and the other σ-bonded to Mo (MoC 1.944 ;) and π-bonded to Nb (CO 1.22, NbC 2.22, NbO 2.26 ;). Three types of carbonyl groups present in IV give rise to strong IR bands at 1870, 1700 and 1560 cm?1 assigned to the terminal, μ-bridging and σ, π-bridging CO groups respectively. Complex IV has a similar structure. The electronic structure of IV and its dissociation across the NbMo bond are discussed. 相似文献
11.
M.G. Voronkov Yu.L. Frolov V.M. Dyakov N.N. Chipanina L.I. Gubanova G.A. Gavrilova L.V. Klyba T.N. Aksamentova 《Journal of organometallic chemistry》1980,201(1):165-177
A new class of organosilicon compounds containing a pentacoordinate silicon atom, (aroyloxymethyl)trifluorosilanes (AFS), has been prepared. The presence of an intramolecular coordinate F3Si ← OC bond is supported by X-ray diffraction, IR spectroscopy and dipole moment data. Si ← O coordination in AFS has been shown to remain intact in the gaseous and liquid states below 420 K as well as in solution in most organic solvents. The dielectric constant of the medium significantly affects the nature of the coordinate Si ← O bond and that of the SiF, CO, COC bonds. In pyridine the intramolecular coordinate Si ← O interaction is disturbed or greatly weakened.At 420–500 K a reversible reaction takes place: ArCF3 α ArCOOCH2SiF3 The changes in enthalpy and entropy are equal in this case: ?△H 8.1 ± 0.7 kcal/mol; ?°S 15.3 ± 0.8 e.u. T 450 K An assignment of bands in the IR spectra of AFS resulting from vibrations of atoms in the SiF3, >CO and COC groups is given. The electron impact-induced primary disintegration of the molecular ion 4-XC6H4COOCH2Si mainly involves abstraction of a fluorine atom. 相似文献
12.
The structure of [Pt2Cl(CO) (μ-Ph2PCH2PPh2)2] [PF6] was determined by -ray methods and refined to = 0.082, using diffractometric intensities of 5646 independent reflections. The crystals are monoclinic, space group 21/, = 12.919(3), = 15.576(6), = 25.151(5)Å, β = 94.82(3)°, = 4. They are built of octahedral hexafluorophosphate anions and dinuclear platinum(I) cations. The latter contain PtCl and PtCO fragments linked to one another by a PtPt σ-bond and by two bridging bis(diphenylphosphino)methane ligands. The platinum atoms are in square planar environments and the dihedral angle between the two coordination planes is 40.1°. Selected bond lengths are: PtPt 2.620(1), PtCl 2.384(5), PtC 1.89(3) and PtP 2.291(5) – 2.308(5)Å. 相似文献
13.
B. Csákvári Zs. Wagner P. Gömöry F.C. Mijlhoff B. Rozsondai I. Hargittai 《Journal of organometallic chemistry》1976,107(3):287-294
An electron diffraction determination of the molecular geometry of hexamethyldisiloxane has removed much of the uncertainty concerning this structure. The length of the SiO bond and the SiOSi bond angle were determined to be 1.631 ± 0.003 Å and 148 ± 3°, respectively. The experimental data are consistent with a staggered conformation (C2v symmetry) while a model with twist angles around the SiO bonds of about 30° cannot be excluded. The molecule is probably performing large amplitude intramolecular motion. 相似文献
14.
Ulrich Schubert 《Journal of organometallic chemistry》1980,197(3):269-274
9-Fluorenyltris(trimethylsilyl)silane (A) reacts with chlorine in CCl4 to give dichloro-9-fluorenyltrimethylsilylsilane (B) in good yield. B is characterized spectroscopically and by X-ray structure analysis; it crystallizes in the triclinic space group P with a 950(2), b 1367(3), c 1138(2) pm, α 137.5(1), β 109.9(2), γ 89.8(2)°. The conformation of B is staggered with approximate Cs-symmetry; C(9)Si 187.6(5), SiSi 233.2(4), SiCl 207.1(3) and 205.3(3) pm. 相似文献
15.
Crystals of oxo-bis[tribenzylgermanium(IV)], O[(PhCH2)3Ge]2, are rhombohedral, space group R, having a = 9.621(2) Å, α = 85.48(3)°. The structure was solved by Patterson methods using diffractometer data and refined by full-matrix least squares to R = 0.0876. The structure consists of molecules lying along the 3-fold axis of the unit cell, in which the GeOGe fragments are strictly linear and centrosymmetric. The GeO distance is 1.730(1) Å and the GeC distance is 1.980(5) Å. 相似文献
16.
Ce6Mo10O39 crystallizes in the triclinic system with unit-cell dimensions (from single-crystal data) a = 10.148(5), Å, b = 18.764(6), Å, c = 9.566(5), Å, α = 103.12(7)°, β = 78.07(7)°, γ = 107.69(7)°, and space group . The structure was solved using direct methods with 3113 countermeasured reflections (MoKα radiation), and refined using Fourier and least-squares techniques to a conventional R of 0.039 (ωR = 0.047). Ce6Mo10O39 has a structure that consists of isolated MoO4 tetrahedra together with one corner-shared pair of tetrahedra, linked to irregular eight-coordinate Ce(III) polyhedra. The average MoO distance of 1.77 Å, and average CeO distance of 2.52 Å are in good agreement with previously reported values. 相似文献
17.
The crystal structures of SiPb2S4 and SiPb2Se4 were determined from three dimensional X-ray diffraction data collected with Mo radiation. Both structures are monoclinic with space group and 4 formula units per unit cell. Lattice dimensions for SiPb2S4 are a = 6.4721(5) Å, b = 6.6344(9) Å, c = 16.832(1) Å, and β = 108.805(7)°. For SiPb2Se4, a = 8.5670(2) Å, b = 7.0745(3) Å, c = 13.6160(3) Å, and β = 108.355(3)°. The Si is tetrahedrally coordinated to S and Se with SiS about 2.10 Å and SiSe about 2.27 Å. The structural framework can be described as consisting of trigonal prisms of S or Se atoms which form a prismatic tube by sharing the triangular faces. These tubes in turn share edges to form corrugated sheets, with the unshared edges projecting alternately on each side of the sheet. The structures are very similar but not identical. In the sulfide one Pb is in sevenfold coordination and the other crystallographically independent Pb is in eightfold coordination. The PbS distances range from 2.82–3.50 Å. In SiPb2Se4 both Pb atoms are in sevenfold coordination. PbSe distances range from 2.97 to 3.54 Å. In the sulfide the Pb atoms form a zig-zag chain within the channels formed by the prismatic tubes while in the selenide they are in a straight line. 相似文献
18.
The structure of NaBD4 was determined from powder neutron data and refined using Rietveld's method. The compound has a sodium chloride-type structure, in space group , Å, BD, 1.160(7); angle DBD, 109.5(2)° at 295 K, with D atoms tetrahedrally oriented about B (at , etc.), and along all cube diagonals. This gives a random distribution of BD?4 tetrahedra in two different configurations. 相似文献
19.
Neutron diffraction studies on polycrystalline UF6 have been carried out at 193°K and 293°K. At both temperatures, UF6 is orthorhombic with the space group Pnma (D162h) and Z = 4. Measured lattice parameters are a = 9.924 (10) Å, b = 8.954 (9) Å, c = 5.198 (5)Å at 293°K and a = 9.843 (11), b = 8.920 (10), c = 5.173 (6) Å at 193°K. The neutron diffraction patterns were analyzed by the least-squares profile-fitting technique. The final values of over the pattern points, where Ioi is a background corrected measured intensity, were 0.081 at 193°K and 0.133 at 293°K.On cooling, the hexagonal close-packing tends to become more regular, and the FF distances external to a UF6 octahedron contract. The octahedra are nearly regular with a mean UF distance of 1.98 Å, a mean FF edge of 2.80 Å, and a FUF angle of 90.0° at 193°K. 相似文献
20.
The molecular structure of euparotin, a highly oxygenated sesquiterpene of the guaianolide type, has been determined by crystal-structure analysis of euparotin bromoacetate. The bromo-derivative crystallizes from benzene-petrol as a benzene solvate, C22H25O8Br·C6H6, crystals of which are monoclinic, of space group C2, with a = 34·85, b = 7·04, c = 10·90 Å, β = 106°35′, and Z = 4. The atomic co-ordinates were determined by Fourier and least-squares calculations which employed 1947 photographic |F0| values and converged at R = 12·8% with isotropic thermal parameters for the C and O atoms and anisotropic parameters for the Br atom. The absolute configuration was established by the anomalous-dispersion effect. The cycloheptane ring of the sesquiterpenoid has a conformation which is closer to a twist chair (C2) than a chair (Cs) form, and a survey shows that this is also true for other perhydroazulene sesquiterpenoids. In the α-methylene-γ-lactone of euparotin and several other sesquiterpenoids the CCCO torsion angle has the same sign as the C(α)C(β)C(γ)-O torsion angle, establishing the basis for Stöcklin et al's correlation between the position and stereochemistry of lactone fusion and the sign of the Cotton effect of the n → π* transition of the CCCO chromophore. 相似文献