Search results for "molecule"
showing 10 items of 5162 documents
Über polygermane
1986
Abstract The synthesis of GePh4 and Ge2Ph6 by Grignard reaction in THF or ether/toluene leads to the by-products Ge3Ph8 (up to 11%) and Ge4Ph10 (up to 18%) which is dependant on using an excess of Mg. A quantitative analysis of the resulting products by HPLC and a semipreparative separation by column, flash, and HPL chromatography is described. The crystal structures of Ge3Ph8 (R = 0.075) and Ge4Ph10 · 2C6H6 (R = 0.054) have been determined. Ge4Ph10 has Ci symmetry and both chain conformations are well staggered (49–70° for Ge3Ph8, 53–66° for Ge4Ph10). The GeGe distances and GeGeGe angles are 244 pm and 121° (Ge3Ph8), and 246 pm and 118° (Ge4Ph10).
Interaction of methylmercury(II) with the bifunctional ligand o-diphenylphosphinobenzoate, dpb. Synthesis and characterization of [(dpb)HgMe] and [(d…
1998
Abstract The complex [(dpb)HgMe] (1) is obtained by reaction of MeHg(OH) with o-diphenylphosphinobenzoic acid (Hdpb); alternatively the solvate [(dpb)HgMe] · 0.5H2O · 0.5C5H5N (1bis) can be prepared by reacting MeHgCl with Hdpb and pyridine. The derivative [(dpbo)HgMe] (2), where dpbo is o-diphenylphosphinoxidebenzoate, is formed by reaction of 1 or 1bis solutions with atmospheric oxygen. Crystal data for 1bis: monoclinic, space group P2/n, a=10.413(4), b=9.831(3), c=20.674(3) A, β=102.51(3)°, Z=2. Crystal data for 2: triclinic, space group P1, a=11.535(2), b=12.897(5), c=13.275(7) A, α=88.31(4), β=73.65(4), γ=85.27(4)°, Z=2. In 1bis the mercury atom displays a distorted linear fashion, bei…
3,4-Bis(4-fluorophenyl)-1,2,5-oxadiazole 2-oxide
2006
The title compound, C14H8F2N2O2, also known as di(4-F-phenyl)furazan N-oxide, was found as a side product in the synthesis of isoxazole derivatives. The are two molecules in the asymmetric unit. The bond length of the dipolar N—O unit is 1.107 (7) A. X-ray analysis confirmed the compound to have the desired structure
Towards multifunctional magnetic systems through molecular-programmed self assembly of Re(IV) metalloligands
2015
Abstract The molecular-programmed approach based on the use as ligands of tailor-made metalloligands containing stable six-coordinate rhenium(IV) as paramagnetic centres is presented in this review article. A relatively large amount of spin density is covalent-delocalized away from the rhenium to the peripheral atoms of the ligands in the case of the Re(IV) metalloligands, as shown by polarized neutron diffraction experiments and density functional theory calculations. This feature accounts for the significant through space-magnetic interactions that occur in most of its mononuclear species and more interestingly it also explains the strengthening of the magnetic interactions in the heterom…
Anionic halide···alcohol clusters in the solid state.
2014
The cationic (1,3,5-triazapentadiene)Pt(II) complexes [1](Cl)2, [2](Cl)2, [3](Br)2, and [4](Cl)2, were crystallized from ROH-containing systems (R = Me, Et) providing alcohol solvates studied by X-ray diffraction. In the crystal structures of [1-4][(Hal)2(ROH)2] (R = Me, Et), the Hal(-) ion interacts with two or three cations [1-4](2+) by means of two or three or four contacts thus uniting stacked arrays of complexes into the layers. The solvated MeOH or EtOH molecules occupy vacant space, giving contacts with [1-4](2+), and connects to the Hal(-) ion through a hydrogen bridge via the H(1O)O(1S) H atom forming, by means of the Hal(-)···HOR (Hal = Cl, Br) contact, the halide-alcohol cluster.…
Synthesis of μ-C2S44− Cobalt Complexes by Activation of the 1,3,4,6-tetrathiapentalene-2,5-dione, and Electrochemical Study of [(Cp*Co)2(μ-C2S4)]
2002
The bimetallic complex [Cp(*)Co)2(μ-C2S4)] in which the two metal centres are linked by an ethylenetetrathiolate C2S44− unit, was synthesized in high yield by oxidative addition of 1,3,4,6 tetrathiapentalene-2,5-dione to [Cp(*)Co(CO)2]. The X-ray crystal structure of the intermediate product Cp*Co(dmid) (dmid2− = 4,5-disulfanyl-1,3-dithiol-2-onate) is presented. The electrochemical behaviour of the [(Cp*Co)2(μ-C2S4)] complex was studied in detail in the oxidative range. This study has shown that the nature of the product obtained after oxidation depends on the presence of complexing agent in the solution. The mechanism has been elucidated in a CH2Cl2 solution in the presence of P(OMe)3. In …
Antioxidative succinobucol–sterol conjugates: Crystal structures and pseudosymmetry in the crystals
2012
Abstract An extensive study to attach succinobucol to sterols has provided conjugates which comprise two pharmaceutically important compounds into one entity where the components are expected to have a synergistic effect. The motivation to design these novel conjugates was the need to broaden the armamentarium of current agents used in the treatment of atherosclerotic diseases and type 2 diabetes. In desire for detailed information of these compounds in solid state, which also have an influence to their physiological activity, systematic crystallization experiments were performed and as a result, X-ray quality single crystals were obtained from four succinobucol–sterol conjugates. All of th…
Solution stoichiometry determines crystal stoichiometry in halogen-bonded supramolecular complexes
2007
The behavior of the methylisonicotinate (MINC) building block as halogen bonding-acceptor module has been investigated in the solid state. Both the N and the O atoms of MINC interact with the iodine atoms of 1,4-diiodotetrafluorobenzene (DITFB) giving rise to N⋯I and O⋯I interactions. Hierarchy between these interactions allows the control of the composition and thus the structure of the supramolecular complex, according to the composition of the reaction mixture. A structure based on an infinite chain and a trimeric supermolecule have been obtained starting from a 1 ∶ 1 MINC/DITFB stoichiometry or by using a large excess of MINC, respectively. While the former structure shows simultaneous …
Synthesis and Crystal Structure of Ln3(OH)(CrO4)4 · 3.5H2O (Ln = Pr, Nd) and Ln2(OH)2(CrO4)2 (Ln = Tb, Gd): Thermal Behavior and Infrared Spectra of …
1993
Abstract Crystal structures of Ln 2 (OH) 2 (CrO 4 ) 2 ( Ln = Gd, Tb) and Ln 3 (OH)(CrO 4 ) 4 · 3.5H 2 O ( Ln = Pr, Nd) were determined by a conventional single-crystal X-ray diffraction technique. Crystals of Ln 2 (OH) 2 (CrO 4 ) 2 ( Ln = Gd, Tb) are monoclinic, space group P 2 1 / c (no. 14) with lattice parameters a = 8.2454(4) A, b = 11.3834(5) A, C = 12.1420(8) A, and β = 136,590(5)°, Z = 4, D x = 4.92 mg · m -3 for Gd 2 (OH) 2 (CrO 4 ) 2 and a = 8.214(1) A, b = 11.348(1) A, c = 12.094(2) A, and β = 136.59(1)°, Z = 4, D x = 5.01 Mg · m -3 for Tb 2 (OH) 2 (CrO 4 ) 2 . Crystals of Ln 3 (OH)(CrO 4 )) 4 · 3.5H 2 O ( Ln = Pr, Nd) are monoclinic, space group C 2/ c (No. 15) with lattice param…
Coupling between the Thermal Evolution of the Heme Pocket and the External Matrix Structure in Trehalose Coated Carboxymyoglobin
2003
Proteins can assume a very large number of conformations (conformational substates), all concurring to its function. We present experimental evidence for the existence, in trehalose coated carboxymyoglobin, of a structured environment of the protein, tightly coupled to the heme pocket structure, as experienced by the bound CO molecule. This was evidenced by the strict correlation observed between the thermal evolution (300−20 K) of the CO stretching and of the water association bands in samples of carboxymyoglobin embedded in trehalose matrixes of different hydration. This observation put forward the coupling between the degrees of freedom of the matrix and those of the protein. In the drie…