Search results for "Isostructural"
showing 10 items of 158 documents
Defective dicubane-like tetranuclear nickel(II) cyanate and azide nanoscale magnets.
2010
Four tetrameric nickel(II) pseudohalide complexes have been synthesized and structurally, spectroscopically, and magnetically characterized. Compounds 1-3 are isostructural and exhibit the general formula [Ni(2)(dpk·OH)(dpk·CH(3)O)(L)(H(2)O)](2)A(2)·2H(2)O, where dpk = di-2-pyridylketone; L = N(3)(-), and A = ClO(4)(-) for 1, L = NCO(-) and A = ClO(4)(-) for 2, and L = NCO(-) and A = NO(3)(-) for 3. The formula for 4 is [Ni(4)(dpk·OH)(3) (dpk·CH(3)O)(2)(NCO)](BF(4))(2)·3H(2)O. The ligands dpk·OH(-) and dpk·CH(3)O(-) result from solvolysis and ulterior deprotonation of dpk in water and methanol, respectively. The four tetramers exhibit a dicubane-like core with two missing vertexes where the…
Adducts of tin(IV) and organotin(IV) derivatives with 2,2′-azopyridine II. Crystal and molecular structure of SnMe2Br2AZP and further mössbauer and p…
1990
Abstract A series of adducts of tin(IV) derivatives with 2,2′-azopyridine, AZP, has been studied by Mossbauer and X-ray photoelectronic spectroscopies and the crystal and molecular structure of SnMe2Br2- AZP has been determined. The linear correlation of the Mossbauer parameter isomer shift with partial atomic charge on tin suggests the occurrence of a single homologous series of isostructural adducts. The correlation of the Mossbauer parameter quadrupole splitting and C-Sn-C bond angle permits their calculation in SnMe2X2AZP adducts (X = Cl, Br). The N1s binding energies, obtained by XPS data, pointed out two slightly different values for both pyridinic and azo-group nitrogens. The crystal…
Copper(I) Halides (X = Br, I) Coordinated to Bis(arylthio)methane Ligands: Aryl Substitution and Halide Effects on the Dimensionality, Cluster Size a…
2014
Bis(phenylthio)methane (L1) reacts with CuI to yield the 1D-coordination polymer [{Cu4(μ3-I)4}(μ-L1)2]n (1) bearing cubane Cu4I4 clusters as connecting nodes. The crystal structures at 115, 155, 195, and 235 K provided evidence for a phase transition changing from the monoclinic space group C2/c to P21/c. The self-assembly process of CuI with bis(p-tolylthio)methane (L2), bis(4-methoxyphenylthio)methane (L3), and bis(4-bromo-phenylthio)methane (L4) affords the 1D-coordination polymers [{Cu4(μ3-I)4}(μ-Lx)2]n (x = 2, 3, or 4). Compounds 2 and 4 are isostructural with C2/c low temperature polymorph of 1, whereas the inversion centers and 2-fold axes are lost in 3 (space group Cc). The use of b…
Comparison and Rationalization of Droperidol Isostructural Solvate Stability: An Experimental and Computational Study
2014
In order to find a tool for comparison of solvate stability and to rationalize their relative stability, droperidol nonstoichiometric isostructural solvates were characterized experimentally and computationally. For the experimental evaluation of stability, three comparison tools were considered: thermal stability characterized by the desolvation rate, desolvation activation energy, and solvent sorption–desorption isotherms. It was found that the desolvation process was limited by diffusion, and the same activation energy values were obtained for all of the characterized solvates, while the solvent content in the sorption isotherm was determined by the steric factors. Therefore, the only cr…
Rare-earth metal bis(tetramethylaluminate) complexes supported by a sterically crowded triazenido ligand
2010
Complexes [NNN]Ln(AlMe(4))(2) (Ln = Y, La, Nd, Lu) bearing the sterically demanding aryl-substituted triazenido ligand [(Tph)(2)N(3)] (Tph = [2-(2,4,6-iPr(3)C(6)H(2))C(6)H(4)]) can be obtained from homoleptic complexes Ln(AlMe(4))(3) in moderate yields, both via protonolysis with [(Tph)(2)N(3)]H and a salt metathesis reaction pathway utilizing [(Tph)(2)N(3)]K. In the solid state the Y and Lu derivatives are isostructural, with both tetramethylaluminate groups coordinated in an eta(2) fashion, while one of the [AlMe(4)] ligands of the Nd derivative features a distorted eta(2) coordination mode. Due to the high affinity of the triazenido ligand toward the more Lewis-acidic and harder aluminiu…
Isostructural Potassium and Thallium Salts of Sterically Crowded Thio‐ and Selenophenols: A Structural and Computational Study
2008
Because of their similar cationic radii, potassium and thallium(I) compounds are usually regarded as closely related. Homologous molecular species containing either K+ or Tl+ are very rare, however. We have synthesized potassium and thallium salts MEAr* [M, E = K, S (2a); K, Se (2b); Tl, S (3a); Tl, Se (3b); Ar* = 2,6-Trip2C6H3, Trip = 2,4,6-iPr3C6H2] derived from terphenyl-substituted thio- and selenophenols. In the solid-state structures of dimeric 2a, 2b, 3a, and 3b additional metal-ηn–π-arene interactions to the flanking arms of the terphenyl substituents of different hapticity n are observed. Remarkably, the homologous potassium and thallium complexes 2b and 3b crystallize in isomorpho…
Syntheses and Crystal Structures of two Non-isostructural Copper(I) Chloride and Bromide π-Complexes with (2-Allylthio)benzimidazole of 1:1 Compositi…
2002
By alternating-current electrochemical synthesis crystals of C10H10N2S · CuCl (I) and C10H10N2S · CuBr (II) π-complexes have been obtained and structurally investigated. The symmetry of I is orthorhombic, space group Pbcn, a = 16.799(2) A, b = 7.302(2) A, c = 18.214(2) A, V = 2234.1(9) A3, Z = 8 for C10H10N2S · CuCl composition, R = 0.0635, Rw = 0.0683 for 970 reflections. Crystals of II are monoclinic, space group P21/n, a = 7.4439(5) A, b = 17.6952(3) A, c = 17.0420(7) A, s = 94.662(2)°, V = 2237.4(2) A<3, Z = 4 for (Cu · C10H10N2S)2Br2 composition, R = 0.0463 for 4123 reflections. (2-Allylthio)benzimidazole moiety acts in both structures discussed as a bidentate ligand, chelating the cop…
Templated Crystallisation of Calcium and Strontium Carbonates on Centred Rectangular Self-Assembled Monolayer Substrates
1998
SrCO3crystals display patterns of templating when grown on tailored self-assembled monolayers (right). As SrCO3 is isostructural with aragonite, comparison of the crystallisation of SrCO3 in the aragonite/strontianite modification with the crystallisation of CaCO3 in all three modifications might yield some insights into which factors are important for crystal growth.
Giant negative magnetoresistance in GdI2
2000
Abstract GdI 2 is a layered d 1 compound which is isostructural with and nominally isoelectronic to the superconductors 2H–TaS 2 and 2H–NbSe 2 . GdI 2 orders ferromagnetically at 276(2) K and displays large negative magnetoresistance ∼70% at 7 T close to room temperature. At 10 K the saturation magnetization is 7.33(5) μ B in good agreement with the value predicted from spin polarized band structure calculations.
Effect of pressure on superconductivity in NaAlSi
2012
The ternary superconductor NaAlSi, isostructural with LiFeAs, the ``111'' iron pnictide superconductor, is investigated under pressure. The structure remains stable up to 15 GPa. Resistivity and susceptibility measurements show an increase of ${T}_{c}$ up to 2 GPa, followed by a decrease until superconductivity disappears at 4.8 GPa. Band structure calculations show that pressure should have a negligible effect on the electronic structure and the Fermi surface and thus the disappearance of superconductivity under pressure must have a different origin. We compare the electronic structure of NaAlSi under pressure with that of nonsuperconducting isostructural NaAlGe.