An X-ray study of a 12-crown-4 host-guest complex. Crystal structure of the 4∶6 complex between 12-crown-4 and aminosulfuric acid

The title compound was prepared by treating a methanolic solution of 12-crown-4 with an aqueous solution of aminosulfuric acid. The crystal for X-ray analysis was obtained by recrystallization from acetone. The compound [(12-crown-4)₄·[NH₃SO₃)₆] (1) is monoclinic, space groupP2₁/a,a=21.900(8),b=15.499(5),c=18.079(5) Å, =67.85(2)°. Refinement led to a final conventionalR value of 0.0788 for 3280 reflections. Supplementary Data relating to this publication have been deposited with British Library as Supplementary Publication No. 82160 (22 pages) and include: the list ofF _obs,F _calc; tables of bond distances, bond angles and selected least square planes, as well as a figure of 12-crown-4 in C₄-conformation.     

Crystal Structure of[La(NO_3)_3(12-crown-4)-(H_2O)](12-crown-4)

ＣｒｙｓｔａｌＳｔｒｕｃｔｕｒｅｏｆ［Ｌａ（ＮＯ_３）_３（１２－ｃｒｏｗｎ－４）－（Ｈ_２Ｏ）］（１２－ｃｒｏｗｎ－４）ＭａｏＪｉａｎｇ－Ｇａｏ；ＪｉｎＺｈｏｎｇ－Ｓｈｅｎｇ；ＹｕＦｅｎｇ－Ｌａｎ（ＬａｂｏｒａｔｏｒｙｏｆＲａｒｅＥａｒｔｈＣｈｅｍｉ?..     

A computational investigation of the electronic properties of Octahedral Al n N n and Al n P n cages (n = 12, 16, 28, 36, and 48)

Density functionla theory (DFT) calculations are performed to characterize geometric and electronic features of the octahedral Al _n N _n and Al _n P _n cages (n = 12, 16, 28, 32, and 48). Toward this aim, ¹⁵N, ²⁷Al, and ³¹P chemical shielding (CS) tensors as well as natural charge analyses are calculated for the optimized structures. CS parameters detect three distinct electronic environments for atoms within the Al _n N _n and Al _n P _n cages. The chemical shifts of N2 sites belonging to a hexagon and surrounded by three hexagons and a square obtained are different from those of N3 sites belonging to a hexagon that is surrounded only by hexagons—due to different curvatures exerted at the sites with different local structures. In addition, there is an increasing tendency in the Δσ values of the three local structures, Δσ (N1) > Δσ (N2) > Δσ (N3), N1 sites belonging to four-membered rings. The chemical shieldings of those Al and P sites belonging to a hexagon that is surrounded only by hexagons in the cages (360.7–366.7 and 496.5–514.7 ppm) are close to those previously reported for AlP nanotubes. Three distinct electrostatic environments around the N, Al, and P nuclei are also confirmed by the calculated natural charges. It should be noted that the positively charged Al atoms on the cages turn out to be the available sites for adsorption of H2 molecules.     

Single crystal growth and structural characterization of four complex uranium oxides: CaUO4, β-Ca3UO6, K4CaU3O12, and K4SrU3O12

Single crystals of complex uranium oxides, CaUO₄, β-Ca₃UO₆, K₄CaU₃O₁₂ and K₄SrU₃O₁₂ were grown from carbonate melts. The crystal structures of the four uranates were determined by single crystal X-ray diffraction. CaUO₄ crystallizes in the hexagonal space group R-3m, with lattice parameters a = 6.2570(7) Å and α = 36.04(2)°. The U⁶⁺ atom in CaUO₄ is 8-coordinate and exhibits hexagonal bipyramidal geometry with six long and two short U–O bonds, typical of a uranyl species. β-Ca₃UO₆ forms in the monoclinic space group P2₁/n, with lattice parameters a = 5.728(1) Å, b = 5.956(1) Å, c = 8.298(2) Å, and β = 90.55(3)°, and adopts a distorted double perovskite structure. K₄CaU₃O₁₂ and K₄SrU₃O₁₂ crystallize in the cubic space group Im-3m with lattice parameters a = 8.483(1) Å and a = 8.582(1) Å, respectively. In all three perovskite-type oxides, the U(VI) cation is located in an octahedral coordination environment and exhibits typical uranyl geometry with four long and two short U–O bonds.     

Macrocycle complexation chemistry. 38. Crystallographic and ultraviolet/visible characterization of nitrobenzo-15-crown-5, dinitrobenzo-15-crown-5, and dinitrodibenzo-18-crown-6·2CH3CN

The crystal structures of three nitrated benzocrown ethers have been determined. Nitrobenzo-15-crown-5 crystallizes in the orthorhombic space group,Pca2₁, witha = 15.367(2),b = 4.8499(8),c = 19.963(5)Å, andD _calc = 1.40 g cm^–3 forZ = 4. Dinitrobenzo-15-crown-5 crystallizes in the monoclinic space group,P2₁/n, witha = 11.716(2),b = 8.495(3),c = 17.441(5)Å, = 108.40(2)° andD _calc = 1.44 g cm^–3 forZ = 4.Dinitrodibenzo-18-crown-6·2CH₃CN ismonoclinic,P2₁/n,witha = 8.138(2),b = 20.435(9),c = 15.953(9)Å, = 100.55(4)° andD _calc = 1.36 g cm^–3 forZ = 4. The nitro substituents are in the plane of the benzo ring except in the sterically congested dinitrobenzo-15crown-5. The observed crown ether conformations are similar to their substituted analogs.For part 37, see reference [1].     

Syntheses,structures, and properties of transition metal complexes with 2-( n -pyridyl)benzimidazole ( n = 2, 3, and 4)

Three pyridylbenzimidazoles (2-PBIM, 3-PBIM, and 4-PBIM) have been prepared (2-PBIM: 2-(2-pyridyl)-benzimidazole, 3-PBIM: 2-(3-pyridyl)-benzimidazole, 4-PBIM: 2-(4-pyridyl)-benzimidazole). Reactions of several transition metals (Cd²⁺, Cu²⁺, Fe²⁺) with the three ligands gave four new coordination complexes, [(Cd)₂(2-PBIM)₂(CH₃COO)₄] (1), [Cu(3-PBIM)₂(CH₃COO)₂]?·?2H₂O (2), [Cu(4-PBIM)₂(CH₃COO)₂(H₂O)]?·?H₂O (3), and [Fe(4-PBIM)₂(Cl)₂(H₂O)₂] (4), respectively. These four complexes have been characterized by X-ray crystallography, IR spectroscopy, and UV absorption spectroscopy. Thermogravimetric properties of 2 and 4 were also measured. X-ray crystallographic studies reveal that these four complexes are very different, although the ligands are similar in structure. The role of hydrogen-bonding and π–π interactions in extending dimensionality of simple complexes has been discussed.     

Synthesis of 4′4″(5″)-dibenzo-18-crown-6-disulfonic acid disalsolidinide,disalsolinide, and dianabasinide

New disulfamides of dibenzo-18-crown-6 with salsolidine, salsoline, and anabasine were prepared by condensation of the corresponding alkaloids with 4,4(5)-dibenzo-18-crown-6-disulfonyl chlorides.Presented at the 5th International Symposium on the Chemistry of Natural Compounds (Tashkent, Uzbekistan, May 20–23, 2003).Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 413–415, September–October, 2004.     

Synthesis,chemical, and electrochemical characterization of the [Ag13{μ3-Fe(CO)4}] n− (n = 3, 4, 5) cluster anions: X-Ray structural determination of [N(PPh3)2]3 [Ag12(μ12-Ag){μ3Fe(CO)4}8]1

The oxidation of the [Fe(CO)₄]^2– dianion with Ag⁺ salts occurs through a particularinner-sphere mechanism, which involves an intermediate cascade of silver clusters stabilized by Fe(CO)₄ ligands. The last detectable Ag-Fe cluster of the sequence is the [Ag₁₃{-Fe(CO)₄}₈]^3– trianion, which has been selectively obtained by using ca. 1.7 equivalents of Ag⁺ per mole of [Fe(CO)₄]^2–. The [Ag₁₃{-Fe(CO)₄}₈]^3–- trianion has been isolated in a crystalline state with several quaternary cations, and has been characterized by X-ray diffraction studies of its bis(triphenylphosphine)iminium salt. [N(PPh₃)₂]₃ [Ag₁₃{ ₃-Fe(CO)₄}₈]·2(CH₃)₂CO, monoclinic, space group P2₁ (No.4),a = 16.284(2) Å,b =18.767(5) Å,c = 25.905(4) Å, = 90.46(1)°,V = 7916(3) ų,Z = 2,R = 0.0324. The molecular structure of the anion consists of a centered cuboctahedron of silver atoms with the triangular faces capped by Fe(CO)₄ units. Chemical reduction of ( Ag₁₃{ ₃-Fe(CO)₄}₈]^3– affords the corresponding [Ag₁₃{ ₃-Fe(CO)₄)₈]^4–, which in turn gives [Ag₁₃{ ₃-Fe(CO)₄)₈]^5– and [Ag₆{ ₃-Fe(CO)₄}₄]^– upon further reduction. Electrochemical investigations confirm the reversibility of the [Ag₁₃{ ₃-Fe(CO)₄}₈]^3–/4– redox change. Furthermore, in spite of some electrode poisoning effects, evidence of the existence of the [Ag₁₃{ ₃-Fe(CO)₄}₈]^5– pentaanion was obtained. The yet structurally uncharacterized [Ag₆{ ₃-Fe(CO)₄)₄]^2– dianion is quantitatively obtained by reaction of [Fe(CO)₄]^2– with ca. 1.5 equivalents of Ag⁺ or by addition of one equivalent of Ag⁺ to solutions of the [Ag₅{Fe(CO)₄}₄]^3– trianion. All attempts to isolate its quaternary salts as crystalline materials failed owing to formation of amorphous insoluble precipitates. The above series of ₃-Fe(CO)₄ octa-capped cuboctahedral Ag₁₃ clusters can be envisioned as the Ag⁺ . Ag and Ag^– cryptates of the [Ag₁₂{}₃-Fe(CO)₄}₈]^4– cryptand. respectively.Dedicated to Prof L. F. Dahl on his 65th birthday.     

Synthesis of bis[(4,10-diaza-4,10-ditosyl-benzo-12-crown-4) 4′-yl] diaminoglyoxime and its complexes

A new macrocyclic ligand (HL) has been synthesised by reaction of 4-amino-4,10-diaza-4,10-ditosyl-benzo-l2-crown-4 with 1,2-dichloroethanedial-dioxime. Protonation constants of the ligand and overall formation constants have been calculated from potentiometric data using the program TITFIT. Both amino and hydroxyimino groups provide donor atoms together with hydroxyl ions at higher pH values. The order of formation constants of the mononuclear complexes are U(VI)O₂>Cu(II)>Ni(II)=Co(II)>Cd(II).Presented at the Sixth International Seminar on Inclusion Compounds, Istanbul, Turkey, 27–31 August 1995.     

Synthesis, complexation properties and crystal structure of 4'''',5''''-dibromo-oxylyl-17-crown-5 ether

4',5'-Dibromo-o-xylyl-17-crown-5 ether (2BrB17C5) was synthesized,starting from 1,2-dibromo-4,5-bis(bromomethyl)-benzene and tetraethylene glycol,and was characterized by 1H NMR,MS and elemental analysis.Pale yellow prismatic single crystal obtained from anhydrous ethanol was investigated by X-ray structural analysis.The complexation properties toward alkali metal ions were examined using the solvent extraction method and UV absorption spectroscopy.The crown ether was found to be conformationally deformed and oblate-like and is highly selective for lithium ion.     

Spectrophotometric study of the charge transfer complexes of 4′-nitrobenzo-15-crown-5 and benzo-15-crown-5 with iodine in nonaqueous solvents

The formation of charge transfer complex between iodine with 4’-nitrobenzo-15-crown-5（NB15C5） and benzo-15-crown-5 （B15C5） is investigated spectrophotometrically in chloroform and dichloromethane（DCM） solutions at 25℃.The pseudo-first-order rate constants for the transformation process were evaluated from the absorbance-time data and found to vary in the order of DCM > CHCl₃.The values of the formation constant,K_f,for each complex are evaluated from Benesi-Hilebrand equation. Stability of the resulting complex in two solvents was also found to vary in the order of DCM > CHCl₃.     

First-principles calculations on the structures,magnetic, and electronic properties of the (Fe2N)m (m = 1–4) and (Fe3N)n (n = 1–3) clusters

The structures, magnetic, and electronic properties of the ground-state (Fe₂N)_m (m?=?1–4) and (Fe₃N)_n (n?=?1–3) clusters have been investigated by using first-principles. The structure of the (Fe₂N)_m and (Fe₃N)_n clusters is a compromise that the N atoms approach more Fe atoms and the N atoms repel each other. The structural stabilities of the (Fe₂N)_m and (Fe₃N)_n clusters increase with the increasing of the N ratio except for the Fe₆N₃ clusters. The (Fe₂N)_m (m?=?1–4) and Fe₉N₃ clusters exhibit more kinetic stabilities than pure iron clusters. The N substitution can decrease the average spin densities of small iron clusters except for the Fe₆N₂ and Fe₈N₄ clusters. The Fe–N bonds exhibit certain covalent bond characteristics.

     

Nature of the structural distortion and of the chemical bonding in SnM3Rh4Sn12 (M = LaGd,Yb, Ca,Sr, and Th)

The crystal structure of all the Sn(1)M₃Rh₄Sn(2)₁₂ compounds (M = LaGd, Yb, Ca, Sr, and Tb) have been refined from single crystal X-ray diffraction data. Although the compounds with M = La, Ce, Pr, Nd, Sm and Gd have the phase I′ structure the refinements have been carried out by the use of the phase I unit cell. The only significant difference between the two sets of structures lies in the thermal ellipsoid of the Sn(2) atoms. With the exception of the Th compound the major axis of the Sn(2) thermal ellipsoid is on the average 0.06 Å longer for the structures of phase I′ than for those of phase I. The structure of the Th compound exhibits the longest major axis for the Sn(2) thermal ellipsoid, it must contain thus the phase I′ distortion. The absence of the superstructure spots can be explained by a structural disorder. This anomalously long axis has been interpreted as due to a static displacement of the Sn(2) atoms along the Sn(1)Sn(2) bonds. The distortion from phase I to phase I′ consists thus in a loss of point symmetry of the Sn(1)Sn(2)₁₂ polyhedra. A detailed analysis of the variation of the interatomic distances across the series shows that the chemical bonds in these compounds have a covalent/metallic-metallic character as the second-nearest-neighbor interactions are rather strong. However, an electron transfer takes place in these compounds indicating that the bonds have also an appreciable ionic character. The loss of symmetry which takes place when going from phase I to phase I′ is accompanied by a loss of ionic character of the Sn(1)Sn(2)₁₂ polyhedra. The Eu²⁺ and Yb²⁺ compounds contain some appreciable amount of Eu³⁺ and Yb³⁺ cations, respectively.     

Crystal growth,structure determination and magnetism of a new m=3, n=1 member of the A3n+3mA′nB3m+nO9m+6n family of oxides: 12R-Ba12Rh9.25Ir1.75O33

Single crystals of a new Ba–Rh–Ir–O oxide were grown from a molten potassium carbonate flux. The new compound, Ba₁₂Rh_9.25Ir_1.75O₃₃, is structurally related to the 2H-hexagonal perovskite structure and contains pseudo one-dimensional chains of alternating units of ten face-sharing (Rh/Ir)O₆ octahedra and one (Rh/Ir)O₆ trigonal prism. The magnetic susceptibility of Ba₁₂Rh_9.25Ir_1.75O₃₃ is featureless, indicating the absence of magnetic order. The oxide is a semiconductor with a room temperature resistance of 280 Ω.     

Synthesis and applications of (5-substituted benzimidazolo)-benzo-15-crown-5 and 4,4′-bis-benzimidazolo-dibenzo-15-crown-5 for the colorimetric detection of Au3+

In the present work, we have reported the synthesis of benzimidazoles functionalized crown ether derivatives of 4-formyl benzo-15-crown-5/4,4′-diformyl dibenzo-15-crown-5 and substituted diamine pyridine using sulfamic acid as a catalyst in DMSO. These molecules are used for the colorimetric determination of Au³⁺ selectively among other metal cations such as Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Pb²⁺, Hg²⁺, Au³⁺ and Ag⁺ ions_.     

Benzo-12-crown-4 modified N-heterocyclic carbene for organocatalyst: Synthesis,characterization and degradation of block copolymers of ϵ-caprolactone with L-lactide

A set of poly(L-lactide)-poly(?-caprolactone) diblock copolymers (AB) and poly(L-lactide)-poly(?-caprolactone)-poly(L-lactide) triblock copolymers (ABA) with predictable molecular weights and relatively narrow distributions were synthesized by ring-opening polymerization of successively added ?-caprolactone (?-CL) and L-lactide (LLA) using 4-methyl benzo-12-crown-4 imidazol-2-ylidene as catalyst. The effects of polymerization conditions, such as reaction time, temperature, monomer/catalyst molar ratio and monomer concentration on the copolymerization have been discussed in detail. The resulting copolymers were characterized by ¹H-NMR, ¹³C-NMR, IR, GPC and DSC methods which confirmed the successful synthesis of block copolymers of LLA and ?-CL. Hydrolytic degradation of the polymers showed that the PLLA-PCL-PLLA copolymer exhibited faster degradation as compared with the PCL homopolymer in alkaline medium at 37°C.     

Hyperfine interactions in the A3Φ4 and X3Φ4 states of iridium monofluoride, IrF

Laser induced-fluorescence spectra of the 1-0 band of the A(3)Φ(4)-X(3)Φ(4) transition of iridium monofluoride, IrF, have been obtained at near natural linewidth resolution using supersonic molecular beam techniques. The spectra show a complex, clearly resolved hyperfine structure which has significant contributions from the magnetic and quadrupole hyperfine terms in (193)Ir and (191)Ir, both with I = 3/2, and the fluorine magnetic hyperfine term (I = 1∕2). The spectra of both (193)IrF and (191)IrF isotopologues have been assigned and analyzed. The hyperfine structure was interpreted with the aid of atomic hyperfine parameters, which were used to determine the configurational composition of the ground state and to estimate the individual molecular hyperfine parameters.     

Regioselective and Stereoselective Synthesis of the 3-Aryl-4- phosphoryl-1, 2, 4-triazoline-5-ones

Regioselective cyclization of 1-acylthiosemicarbazides has been shown to be an excellent method for the synthesis of triazoles, thiadiazoles and oxadiazoles, with a variety of potential biological activities1-6 and utilities as pharmacological properties7…     

Conductance Study of the Binding of K+ by Dibenzo-pyridino-18-crown-6 and 1,10-N,N′-didecyl-diaza-18-crown-6 in Acetonitrile

The binding of K+ by dibenzo-pyridino-18-crown-6 (B2-py-18-C-6) and1,10-N,N-didecyl-diaza-18-crown-6 (22-DD) has been studiedconductometrically at 10, 15, 20 and 25 °C in acetonitrile. Thecomplexes formed were assumed to have 1 : 1 stoichiometry. The complexes ofK+ with 18-crown-6 (18-C-6) and dibenzo-18-crown-6 (B2-18-C-6) were alsostudied for comparison purposes. The stability constant, K, of a givencomplex and its molar conductance, c, were obtained by subjectingthe conductance data to a non-linear least-squares curve fitting procedure.The values of the enthalpy change, H, the entropy change, Sand the Gibbs free energy, G, associated with the formation of the 1: 1 complexes were derived and compared with relevant literature data. Thevalues of G at 25 °C indicate that the binding capacity of thefour macrocycles follows the order 18-C-6 > 22-DD > B2-18-C-6 >B2-py-18-C-6. The difference between the molar ionic conductance of the freeK+ cation and that of the bound cation, KL+, was estimated and the trend insuch differences correlates with the molecular size of the macrocycle, L.     

Structures,electronic and magnetic properties of the FemOn@Cx (m = 1–3, n = 1–4, x = 50, 60) clusters

The structures, electronic and magnetic properties of the Fe_mO_n@C_x (m?=?1–3, n?=?1–4, x?=?50, 60) clusters have been investigated by using PBE functional. The C₅₀, C₆₀ can significantly increase the structural stabilities of the Fe_mO_n molecules. Fe₂O₃@C₅₀ and Fe₃O₄@C₅₀ are more chemically stable than the Fe₂O₃@C₆₀ and Fe₃O₄@C₆₀ while FeO@C₆₀ is more chemically stable than the FeO@C₅₀. The spin densities of the Fe_mO_n fragments degenerate to zero. Carbon encapsulation leads to the internal charges of the Fe_mO_n fragments transfer from 4 s to 4p orbital.