Crystal structure and phase transition of 2-methoxyanilinium perchlorate-18-crown-6

A new phase transition compound,2-methoxyanilinium perchlorate-18-crown-6(1) {(oCH3OC6H4NH3)+(18-crown-6) ClO4 },has been synthesized and separated as crystals.Differential scanning calorimetry(DSC) measurements show a pair of sharp peaks at 225 K(heating) and 210 K(cooling),indicating the phase transition is first-order.Dielectric anomalies observed at 225 K(heating)and 210 K(cooling) further confirm the phase transition.The crystal structures determined at 298 K and123 K are both triclinic in P 1.The most distinct difference between room-temperature and lowtemperature structures is the order–disorder transition of the host 18-crown-6 molecule,which is the driving force of the phase transition.     

Supramolecular 1D assemblies of polyfluorinated arylenediamines and 18-crown-6

Rods (1D assemblies) formed by alternate crown ether and arylenediamine molecules are the motif of the supramolecular architecture of crystals of molecular associates of 18-crown-6 with tetrafluoro-1,4- and -1,3-phenylenediamines, hexafluoro-2,6- and -2,7-naphthylenediamines. Molecules in the assemblies are arranged via H-bond predominantly between the crown ether oxygen atoms and the polyfluoroarene amino group hydrogen atoms. Influence of the amino groups mutual arrangement and the aromatic framework size on the crystal supramolecular architecture is characterized. Specific melting heats of the crystalline 1D assemblies of para- and pseudo-para-arylenediamines are higher than those of meta- and pseudo-meta-analogs; the associates having higher melting heats selectively crystallize from solutions of isomeric phenylene- or naphthylenediamine mixtures.     

Supramolecular Compounds of cis-syn-cis-Dicyclohexano-18-crown-6 with Complex Fluoroniobic and Fluorotantalic Acids

Russian Journal of General Chemistry -     

The 1 : 1 complexes between benzo-18-crown-6, 18-crown-6 and aminosulfuric acid

The title compounds were prepared by treating a methanol solution of the corresponding crown ether with an aqueous solution of aminosulfuric acid.Crystals of [benzo-18-crown-6·H₂NSO₂OH] suitable for X-ray crystallography were obtained by recrystallization from methanol. The crystals are orthorhombic, space groupP2₁2₁2₁,a = 14.310(7),b = 12.516(4),c = 10.890(4) Å. Refinement led to a final conventionalR value of 0.051 for 909 reflections.Crystals of [18-crown-6·H₂NSO₂OH] suitable for X-ray crystallography were obtained by recrystallization from acetone. They are orthorhombic, space groupP2₁2₁2₁,a = 17.027(6),b = 14.866(5),c = 8.345(4) Å. The structure was solved by a heavy atom method and refined to an agreement value of 0.067.     

Non-classical hydrogen bonding in [K(1-aza-18-crown-6)]BH4 and its 18-crown-6 counterpart

The extended structures of [K(1-aza-18-crown-6)]BH(4) and its 18-crown-6 analogue exhibits significantly different primary and secondary stabilizing interactions. However, their respective ion pairs display similar cation-to-anion interactions, in spite of the differences in the nature of the crown ether ligand.     

A stereoselective reduction of dibenzo-18-crown-6 ether to dicyclohexyl-18-crown-6 ether

Dibenzo-18-crown-6 ether is reduced to dicyclohexano-18-crown-6 ether under very mild conditions (room temperature and atmospheric hydrogen pressure) in the presence of rhodium salt and phase-transfer reagents. Control over the stereoselectivity of the reduction can be achieved through the proper choice of the phase-transfer agent. Moreover, at higher pressure, the stereoselectivity can be increased up to a 95/5 ratio of the syn/anti isomers of the dicyclohexano-18-crown-6 ether.     

Dibenzo-18-crown-6 diaqua(dibenzo-18-crown-6)potassium triiodide: Synthesis and crystal structure

A new compound, dibenzo-18-crown-6 diaqua(dibenzo-18-crown-6)potassium triiodide [K(Db18C6)(H₂O)₂)⁺ · I₃⁻ · Db18C6 (I), is synthesized and studied by X-ray crystallography. The crystals of compound I are orthorhombic: a = 22.065 ?, b = 22.140 ?, c = 9.433 ?, Z = 4, space group Pccn. Structure I is solved by a direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.098 for all 5974 unique reflections. Structure I contains the following asymmetric units: a half of the I₃⁻ centrosymmetric anion and two halves of the mixed equally average [K(Db18C6)(H₂O)₂]⁺ host—guest complex cation (a) and a free Db18C6 molecule, each stacked on the axes 2 of the perpendicularly averaged plane of the eighteen-membered macroheterocycle. In complex I, both Db18C6 molecules (a and b) have a “butterfly” conformation with approximate symmetry C _2v . Original Russian Text ? A.N. Chekhlov, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 3, pp. 516–520.     

4′,4″(5″)-dibenzo-18-crown-6-diaryl-acetohydroxamic acids

4′,4″(5″)-(Dibenzo-18-crown-6)diarylacetohydroxamic acids were obtained by the reaction of DB18C-6 with β-nitrostyrenes under the influence of polyphosphoric acid. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 838–840, June, 2006.     

二环己基并18冠6的制备方法

二苯并-18－冠-6;二环己基并18冠6的制备方法     

Interaction of Iodine with Hexaaza-18-crown-6 and Tetraaza-14-crown-4 in Chloroform Solution

Interactions of hexaaza-18-crown-6 (HA18C6) and tetraaza-14-crown-4 (TA14C4) with iodine have been investigated spectrophotometrically in chloroform solution. The observed time dependence of the charge-transfer band and subsequent formation of I₃ ^- in solution were related to the slow transformation of the initially formed 1:1 macrocycle. I₂ outer complex to an inner electron donor-acceptor (EDA) complex, followed by fast reaction of the inner complex with iodine to form a triiodide ion, as follows: macrocycle + I₂→_fast ^K _f macrocycle.I₂ (outer complex) macrocycle.I₂ (outer complex) →^slow (macrocycle.I⁺)I^- (inner complex) macrocycle.I⁺)I^- (inner complex) + I²→^slow (macrocycle.I⁺)I₃ ^-. The pseudo-first-order rate constants at various temperatures for thetransformation process were evaluated from the absorbance-time data. The activation parameters (E_a, Δ H^?, and Δ S^?) for thetransformation were obtained from the temperature dependence of the rate constants. The stoichiometry and formation constants of the resulting EDA complexes have also been determined. It was found that the (TA14C4.I⁺)I₃ ^- is more stable the (HA18C6.I⁺)I₃ ^- complex in chloroform solution.     

Extraction of rare-earth elements by alkylated dibenzo-18-crown-6 and dicyclohexano-18-crown-6 from acid solutions

The extraction of rare-earth elements (REE) by alkylated crown ethers (dibenzo-and dicyclohexano-18-crown 6; DB18C6 and DCH18C6) from acid solutions in the chloroform-water system is studied. The extraction of the REE with DCH18C6 and its alkylated derivatives in the presence of trichloroacetic acid (TCA) is far more efficient than the extraction with DB18C6 and its alkylated derivatives or when nitric or acetic acid is used instead of TCA. The distribution coefficients for the cerium metals are far higher than for the yttrium metals. The metal: crown ether ratio in the extracted complex in all cases is 1:1.     

Reaction of lead halides with 18-crown-6 and dicyclohexano-18-crown-6: Solvent extraction,synthesis and crystal structure of [Pb(18-crown-6)I2]

Abstract

Solvent extraction of lead halides with 18-crown-6 (18C6), dicyclohexano-18-crown-6 (DC18C6, cis-syn-cis and cis-anti-cis isomers) in chloroform was studied, and the extraction constants corrected for side reactions and ionic strength effects were obtained. The compounds of the same composition as those being extracted were also isolated in crystal form. The molecular structure of the [Pb(18C6)I₂] complex has been determined. Crystals are monoclinic, P2₁/n, a = 11.237(2), b = 10.992(2), c = 8.139(2)Å, β = 97.32(3)°, V = 997.1(7)ų, D_calc = 2.416(2)gcm^?3, Z = 2 for the composition C₁₂H₂₄O₆PbI₂. The final R-factor is 0.043 for 558 unique reflections. The lead atom is coordinated to six oxygen atoms of the crown ether and two iodine atoms forming a hexagonal bipyramidal coordination polyhedron. The 18C6 molecule and the two halogen atoms form a hydrophobic coating for the lead atom which may be assumed to be the main reason of high extraction constants of the iodine complexes. For 10-coordinate lead ion (bidentate counter ions) the cis-syn-cis isomer of DC18C6 appears to be the best extraction reagent, while for 8-coordinate lead ion (monodentate halide anion) no difference between isomers was observed.     

Reaction of H2PtCl6 with 18-crown-6 and dibenzo-18-crown-6 in 1,2-dichloroethane and acetonitrile

Compounds of the compositions [2(18-crown-6)6(H₂O)2(C₂H₄Cl₂){Pt²⁺(C₂H₄)}(Pt₂Cl₁₀)^2–], [4(18-crown-6)2(OH₃)⁺2(OH₂)2(NH₃)(Pt₂Cl₁₀)^2–], [(dibenzo-18-crown-6)6(H₂O){Pt²⁺(C₂H₄)}(Pt₂Cl₁₀)^2–], and [4(dibenzo-18-crown-6)2(OH₃)⁺2(OH₂)2(NH₃)Pt₂Cl₁₀)^2–] were prepared by reactions of H₂PtCl₆ with 18-crown-6 and dibenzo-18-crown-6.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 10, 2004, pp. 1593–1599.Original Russian Text Copyright © 2004 by Guseva, Busygina, Khasanshin, Polovnyak, Yarkova, Yusupov.This revised version was published online in April 2005 with a corrected cover date.     

Diformazyl derivatives of dibenzo-18-crown-6

New derivatives of the macrocyclic polyether dibenzo-18-crown-6 that contain formazyl groupings in the aromatic rings were synthesized. The complexing ability of the polyether ring and the formazyl groupings was studied. Complexes of two types, viz., those that contain a transition metal and those that simultaneously contain a transition metal and an alkali or alkaline earth metal, were isolated in crystalline form.DeceasedTranslated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1479–1483, November, 1981.     

微波辅助二苯并-18-冠-6的合成

以邻苯二酚与二甘醇二取代物为原料,氢氧化钾为碱和模板剂,在微波辅助下,采用“一锅煮”法合成二苯并-18-冠-6。 经单因素及正交实验考察了原料、溶剂、时间、温度和功率对反应收率的影响,获得了最佳的工艺条件：以邻苯二酚与二氯乙醚为原料,二甲亚砜为溶剂,反应温度70 ℃,时间60 min,功率500 W,收率可达46.3%。     

Diaquabromo(18-crown-6)rubidium and triaqua(18-crown-6)barium dibromide monohydrate: Synthesis and crystal structures

Two complexes are synthesized: diaquabromo(18-crown-6)rubidium [RbBr(18-crown-6)(H₂O)₂] (I) and triaqua(18-crown-6)barium dibromide monohydrate [Ba(18-crown-6)(H₂O)₃]²⁺ 2Br^? · H₂O (II). The orthorhombic structure of compound I (space group Pnma, a = 10.124 Å, b = 15.205 Å, c = 12.544 Å, Z = 4) and the monoclinic structure of compound II (space group C 2/c, a = 17.910 Å, b = 10.315 Å, c = 14.879 Å, β = 123.23°, Z = 4) are determined by a direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.063 (I) and 0.042 (II) for all 2293 (I) and 3363 (II) independent measured reflections (CAD-4 automated diffractometer, λMoK _α). The complex molecule [RbBr(18-crown-6)(H₂O)₂] in compound I and the randomly disordered cation [Ba(18-crown-6)(H₂O)₃]²⁺ in compound II are of the host-guest type: their Rb⁺ or Ba²⁺ cation (its coordination number is nine) is located in the cavity of the 18-crown-6 ligand and coordinated by all six O atoms. In structure I, the coordination polyhedron of Rb⁺ is a distorted hexagonal pyramid with a triple apex at the Br^? ligand and two O atoms of the water molecules. In structure II, the Ba²⁺ polyhedron is a distorted hexagonal bipyramid with one apex at the O atom of the water molecule and the other split apex at two O atoms of water molecules.