The chemistry and the stereochemistry of poly(N-alkyliminoalanes) : V. The preparation and crystal structure of the pentamer [(HalN-i-Pr)2(H2AlNH-i-Pr)3]

The compound [(HAlN-i-Pr)₂(H₂AlNH-i-Pr)₃] has been prepared and the crystal and molecular structure determined by an X-ray analysis, carried out with three-dimensional data collected on a diffractometer. The molecule is made up of a cyclohexane-type ring, [(HAlN-i-Pr)₂(H₂AlNH-i-Pr)], in skewboat conformation, on each side of which is bonded an -H₂AlNH-i-Pr- bridging unit between a nitrogen atom and an aluminum atom of the ring. The molecule lies on a binary axis of the crystal, but this symmetry is fulfilled only by a statistical orientation of the asymmetric molecular units (the statistical model is not however completely defined). The AlN bond lengths range from 1.901 to 1.985 Å; the average NC bond length is 1.527(9) Å. Main crystal data are: monoclinic space group C2/c; a = 10.15(2), b = 21.64(3), c = 12.84(2) Å, β = 111.9(5)°; Z = 4; calculated density 1.095 g/cm³. The structure was solved by direct methods and block-matrix least-squares converged to an R value of 5.6%.     

The chemistry and the stereochemistry of poly(N-alkyliminoalanes) : XVI. The crystal and molecular structure of the compound [HAlNCH(CH3)C6H5]6·13 C6H14

The crystal structure of [HAlNCH(CH₃)C₆H₅] ₆·$\text{1}\text{3}$ C₆H₁₄ has been determined by single crystal three-dimensional X-ray analysis. Block-matrix least-squares refinement led to conventional R factor of 0.08. The molecule is built up of a prismatic hexagonal framework, (AlN)₆. Average AlN distances are 1.893(6) and 1.981(7) Å in the six-membered rings and in transverse bonds, respectively. Crystal data: hexagonal, space group P6₃, a 22.296(5), c 18.144(4) Å, V 7811.2 ų, Z = 6, D_c 1.16 g cm^?3.     

The chemistry and the stereochemistry of poly(N-alkyliminoalanes) : IV. The preparation and crystal structure of [H(HAlN-i-Pr)5AlH2]·LiH/Et2O

The compound [H(HAlN-i-Pr)₅AlH₂]·LiH/Et₂O has been prepared, and its crystal and molecular structure has been determined from single-crystal, three-dimensional X-ray diffractometer data. The molecular structure is a pseudohexameric cage, consisting of a five-membered fragment, AlNAlNAl, crosslinked to a six-membered cyclohexane type ring, (AlN)₃. The hydrogen atom of LiH is indistinguishable from the other hydridic hydrogens, so that the N-isopropyliminoalane part of the molecule may be considered as an anion with a formal charge of ?1. The lithium cation is linked to two adjacent molecules through three LiHAl bridges, the fourth position of its tetrahedral coordination being occupied by the oxygen of diethyl ether. Large distortions of the tetrahedral valence angles occur, both on the aluminum atoms and on the nitrogen atoms, together with a noticeable spread of the AlN bond lengths, averaging 1.919(4) Å. Colourless crystals of the compound have the following crystal data: orthorhombic space group Pna2₁; a = 19.76(2), b = 10.38(1), c = 16.60(2) Å; Z = 4; calculated density 1.048 g/cm³. The structure has been refined by block-matrix least-squares methods, using 2487 independent reflections, to an usual R factor of 5.9%.     

The crystal structure of the acetone adduct oftrans-methyliodo-8-hydroxyquinolinatocarbonyltriphenylphosphinerhodium(III)

Summary trans-Methyliodo-8-hydroxyquinolinatocarbonyltriphenylphosphinerhodium(III) was synthesised by means of the oxidative addition of MeI to 8-hydroxyquinolinatocarbonyltriphenylphosphinerhodium(I). The compound crystallizes in the triclinic space group, , witha=13.423(5),b=14.500(3),c=17.562(5)Å, =68.30(2), =75.15(2), =86.31(2)°. The final R value was 0.052 for the 11302 observed reflections. There are two [Rh(ox)(CO)(PPh₃)(Me)(I)] and one Me₂CO molecule in the asymmetric unit. The rhodium atom has an octahedral configuration with the methyl and iodide ligands in thetrans positions. This structure determination showed that only the alkyl complex is formed during the oxidative addition reaction and thattrans-addition of MeI occurs.     

The chemistry and the stereochemistry of poly(N-alkyliminoalanes) : XV. The crystal and molecular structure of the compounds [((THF)Mg)(HA1N-t-Bu)3] and [((THF)3Ca)(HA1N-t-Bu)3] · THF

The compounds [((THF)Mg)(HA1N-t-Bu)₃] (I) and [((THF)₃Ca)(HA1N-t-Bu)₃] · THF (II) have been structurally characterized from single-crystal diffraction data. The molecular structures are based on an (A1N)₄ “cubane” type framework in which an aluminum is replaced by an alkaline earth metal. According to the size and the coordination of the “foreign” atom (four for Mg, six for Ca) the cubic geometry of the cage is increasingly distorted. Coordination is completed by one molecule of THF to the Mg atom and three molecules to the Ca atom; in II a molecule of THF crystallizes with a cage molecule. Mean MgN and CaN bond distances are 2.090(4) and 2.490(2) Å. Crystal data: I, orthorombic, space group Pbca, a 17.107(2), b 17.305(4) and c 20.220(5) Å, Z = 8, calculated density 1.031 g/cm³; II, orthorombic, space group Pbca, a 20.48(1), b 20.38(1), c 20.51(1), Z = 8, calculated density 1.081 g/cm³.     

The chemistry and the stereochemistry of poly(N-alkyliminoalanes) : IX. Hexameric organoaluminum imides by reaction of (HAIN-iso-C3H7)6 with trialkylaluminums

(HAlN-iso-C₃H₇)₆ reacts with Al(CH₃)₃ or Al(C₂H₅)₃ to give compounds in which the hydridic hydrogens are partially or completely replaced by alkyl groups. The degree of alkylation depends on the reaction conditions and on the nature of the trialkylaluminum. Pure crystalline (CH₃AlN-iso-C₃H₇)₆, its crystallization product with [(CH₃AlN-iso-C₃H₇)₅(HAlN-iso-C₃H₇)] and a mixture of [(C₂H₅AlN-iso-C₃H₇)₄(HAlN-iso-C₃H₇)₂] isomers have been isolated. The reaction of Al(CH₃)₃ or Al(C₂H₅)₃ with iso-C₃H₇NH₂ gives tetramers (CH₃AlN-iso-C₃H₇)₄ and (C₂H₅AlN-iso-C₃H₇)₄.     

The chemistry and the sterechemistry of Poly(N-Alkyliminoalanes: XIII. The crystal and molecular structure of the hexamers (ClAlN-i-Pr)6 and (Me0.83H0.17AlN-i-Pr)6MeAlN-i-Pr)6

The crystall and molecular structures of (ClAlN-i-Pr)₆ (I), and of (Me_0.83H_0.17AlN-i-Pr)₆(MeAlN-i-Pr)₆ have been determined by single crystal three-dimensional X-ray analysis. Block-matrix least-squares refinements led to conventional R factor of 0.039 for I and 0.037 for II. The compounds are isostructural, as the cage molecules consist of a prismatic hexagonal framework, (AlN)₆, similar to that observed for the parent hydrogenated analogue (HAlN-i-Pr)₆.Some differences in bond distances and angles are discussed, in connection with the different Al-bonded substituents. Crystal data: I, trigonal space group R$\text{3}$; a = 17.083(2), c = 9.652(1); Z = 3; D_c 1.46 g cm^?3; II, trigonal space group R$\text{3}$, a = 17.378(3), c = 9.706(3) »; Z = 3; D_c 1.15 g cm^?3.     

Organolanthanoids: VII. The crystal and molecular structure of dibromo-η5-cyclopentadienyltris(tetrahydrofuran)ytterbium(III)

Crystals of dibromo-η⁵-cyclopentadienyltris(tetrahydrofuran)ytterbium(III) are monoclinic, P2₁/n (C_2n⁵, No. 14), with a 15.310(15), b 16.900(17), c 7.968(8) Å, β 96.66(5)° and Z = 4. The ytterbium is pseudo-octahedrally coordinated by a cyclopentadienyl ligand, trans bromines, and mer tetrahydrofuran ligands, and the ytterbium—oxygen distance trans to cyclopentadienyl is longer than the other ytterbium—oxygen bonds.     

[Cr(H2O)3(NCS)3](18-冠-6)的分子和晶体结构

本文报道了[Cr(H2O)3(NCS)3](18-冠-6)配合物的单晶X射线结构 分析 , 并基于分析结果, 对分子的结构特点和晶胞中的堆积方式进行了讨论.     

(Dibenzo-18-crown-6)potassium tetrachloroferrate(III): Synthesis and crystal structure

A new complex [K(Db18C6)]⁺[FeCl₄]^? (I) is synthesized and its structure is studied by X-ray diffraction analysis. The crystals are triclinic: space group P \(\bar 1\), a = 17.998, b = 18.670, c = 19.590 Å, α = 106.61°, β = 104.55°, γ = 113.87°, Z = 8. The structure is solved by a direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.057 by 13 670 independent reflections (CAD-4 automated diffractometer, λMoK _α). All the four independent complex cations [K(Db18C6)]⁺ are host-guest, and in each complex cation the K⁺ cation is localized in the cavity of the Db18C6 crown ligand. The coordination polyhedron of K⁺ (coordination number nine) is a distorted hexagonal bipyramid with the base of all six O atoms of the Db18C6 ligand, the axial vertex at the Cl atom of the [FeCl₄]^? anion, and another bifurcated axial vertex at two Cl atoms of another [FeCL₄]^? anion. All the four independent [FeCL₄]^? anions are orientationally disordered and have somewhat distorted tetrahedral structure. In crystal I, the alternating complex cations [K(Db18C6)]⁺ and [FeCL₄]^? anions form infinite polymer chains by the K-Cl bonds.     

The crystal and molecular structure of 6-oxadihydrouracil

The crystal and molecular structure of 6-oxadihydrouracil (C₃H₄N₂O₃) has been determined by single crystal x-ray diffraction techniques. The compound crystallizes in the space group P2₁ 2₁ 2₁ with four molecules in a unit cell of dimensions: a = 5.106(1)Å, b = 12.461(2)Å and c = 7.112(1)Å. The structure was solved by direct methods and refined to a final value of R = 0.052. The oxauracil ring is non-planar with the C5 atom assuming tetrahedral geometry and the ring oxygen having oxazinal distances and angle (C-O = 1.43₂Å, N-O = 1.40₈Å, and CON angle of 109.0°). The usual hydrogen bonding patterns associated with the uracil ring are absent in this compound.     

Crystal structure of the molecular adduct of antimony(III) fluoride with L-phenylalanine

The crystal structure of a newly synthesized molecular adduct of antimony(III) fluoride with L-phenylalanine of the composition SbF₃(C₉H₁₁NO₂) is determined for the first time (monoclinic crystal system: a = 5.8742(1) ?, b = 6.2079(1) ?, c = 15.5401(3) ?, β = 90.741(1)°, Z = 2, P2₁ space group). The structure consists of SbF₃ molecules and L-phenylalanine bound into polymer chains by bidentate bridging carboxyl groups of amino acid molecules. Weak Sb⋯F(3)^b bonds organize the adjacent chains into polymer ribbons that are bound into layers by N-H⋯F and N-H⋯O hydrogen bonds.     

The crystal and molecular structure of the 2,4,6,8 tetra-t-Bu-phenothiazine 0.5 benzene adduct

The crystal structure of 2,4,6,8-tetra-t-Bu-phenothiazine 0.5C₆H₆ (Pnma space group, a=11.685, b=25.593, c=10.339) shows short intermolecular t-Bu(CH₃)Ph and CH₃CH₃ contacts which allow the formation of well defined channels along the a direction. These channels host one benzene molecule for each pair of phenothiazine molecules. AM1 molecular orbital calculations suggest that there is a strong coupling of the t-Bu groups rotations and the folding of the ring and this in turn makes the phenothiazine skeleton to be less folded than expected from the presence of four electron donating substituents.     

The crystal structure of poly(tetramethylene terephthalate)

The unit cell of poly(tetramethylene terephthalate) is triclinic with parameters a = 5.96 Å, b = 4.83 Å, c (fiber axis) = 11.62 Å, α = 115.2. β = 99.9, and γ = 111.3°; space group P1 , calculated crystalline density 1.41 g/cc. The plane of the benzene ring is found to be inclined by about 15° from the fiber axis, contributing to a shortening of the fiber period as compared to the period expected on the basis of analogy with other members of the terephthalate ester series. The remaining shortening of the fiber period occurs in the ? O? °CH₂? °CH₂? segment of the chain. No abnormally short distances among neighboring chain atoms were observed. A typical texture pattern was found in specimens of this polymer that were cold rolled and subsequently annealed. In this texture the c axis of the unit cell is highly oriented in the rolling direction; the a and b axes of the unit cell are oriented preferentially so that the terephthalate residue lies as close as possible to the plane of rolling.     

1,2-oxazine chemistry—II : The crystal and molecular structure of N-(p-carboxybenzyl)-tetrahydro-1,2-oxazine

The crystal structure of the title compound has been determined from X-ray diffractometer data by direct methods, and refined by full matrix least squares techniques to R = 0·057 for 1231 reflections. The crystals are monoclinic, space group C2/C, cell dimensions a = 1665, b = 987, c = 1443 pm, β = 107·37° and Z = 8. The conformation of the tetrahydro-1,2-oxazine ring is a chair with the N-substituent equatorial. There is evidence of significantly greater torsional angles around the N and O atoms than around the ring C atoms, showing the ring to be more puckered than cyclohexane. The hydrogen bond is between the acid group on one molecule and the ring nitrogen on its neighbour.     

The crystal and molecular structure of (-)-phaseollin

X-ray analysis has defined the molecular structure of (-)-phaseollin C₂₀H₁₈O₄ a pterocarpan with lipophilic antifungal activity, isolated from Phaseolus vulgaris L. The orthohombic crystals belong to the space group P2₁2₁2₁ with a =6.540(3), b = 12.975(6), c = 19.388(4) Å and Z =4. The structure was solved by direct methods from diffractometer data measured with CuKα radiation, and refined to a final R index of 0.083 for the 992 observed terms. The molecular skeleton(I) has a cis B/C ring junction. Viewed down C(6B)-C(7) the conformation is staggered; ring C is envelope whereas ring B is skewed with C(6B) and C(7) lying respectively above and below the plane of the other ring atoms.