Ein Netzwerk aus Iodid-Ionen und Iod-Molekülen in der Kristallstruktur von [Pr(Benzo-15-Krone-5)2]I21

A Three Dimensional Network of Iodide Ions and Iodine Molecules in the Crystal Structure of [Pr(Benzo-15-Crown-5)₂]I₂₁ Black polyhedra of [Pr(benzo-15-crown-5)₂]I₂₁ were grown from an ethanol / dichlormethane solution of PrI₃, benzo-15-crown-5 and I₂. The crystal structure (orthorhombic, P2₁cn, a = 1201.1(1), b = 2168.3(1), c = 2571.1(1) pm, Z = 4) is built up from sandwich like cations [Pr(benzo-15-crown-5)₂]³⁺ and polyiodide anions I₂₁^3-. This unique polyiodide anion exhibits a complex connection pattern of iodide ions and iodine molecules with variable bond lengths forming a complicated network.     

Weak Interactions in Silver Complexes of 15-Crown-5

Abstract

The X-ray crystal structures of two closely related Ag(I) complexes of 15-crown-5 and benzo-15-crown-5 are reported. In the case of [Ag(15-crown-5)₂][SbF₆] 1, pointing one of its oxygen atoms away from the Ag⁺ cation enables one of the crown ligands to take part in an intermolecular C?H…O hydrogen bond. The analogous benzo-15-crown-5 species, [Ag(benzo-15-crown-5)₂][SbF₆] 2, is too rigid to attain the necessary conformation. Crystal data for 1: P2_1/c, a = 8.4481(3), b = 25.5813(9), c = 13.2773(4) Å, β = 101.354(2)°. Z = 4, unique data: 5187 R ₁ [F ² > 2σ(F ²)] 0.0259. Compound 2: P1, a = 8.6511 (15) Å, b =10.2322(18) Å, c = 19.291(3) Å, α = 103.704 (2)°, β = 101.274(2)°, γ = 95.952(2)°, Z = 2, unique data: 5803 R ₁ [F ²>2σ(F ²)] 0.0931.     

Mass-spectrometric investigation of ionophoric derivatives of benzo- and dibenzocrown ethers. 4. 4′-Acyl derivatives of benzo-15-crown-5 and benzo-18-crown-6

The mass spectra of 4-acyl derivatives of benzo-15-crown-5 and benzo-18-crown-6 were studied by the method of direct analysis of the daughter ions (DADI). It was established that the fragmentation of the M⁺ ions of the investigated compounds under electron impact proceeds via the scheme of the McLafferty rearrangement with the simultaneous elimination of ethylene oxide. The degree of occurrence of the McLafferty rearrangement increases with an increase in the length of the side chain.See [3] for communication 3.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 989–901, July, 1987.     

Anion-π interactions—interactions between benzo-crown ether metal cation complexes and counter ions

The loss of X^· radical from [M + Cu + X]⁺ ions (copper reduction) has been studied by the so called in-source fragmentation at higher cone voltage (M = crown ether molecule, X⁻ = counter ion, ClO₄⁻, NO₃⁻, Cl⁻). The loss of X^· has been found to be affected by the presence/lack of aromatic ring poor/rich in electrons. Namely, the loss of X^· occurs with lower efficiency for the [NO₂-B15C5 + Cu + X]⁺ ions than for the [B15C5 + Cu + X]⁺ ions, where NO₂-B15C5 = 3-nitro-benzo-15-crown-5, B15C5 = benzo-15-crown-5. A reasonable explanation is that Anion-π interactions prevent the loss of X^· from the [NO₂-B15C5 + Cu + X]⁺ ions. The presence of the electron-withdrawing NO₂ group causes the aromatic ring to be poor in electrons and thus its enhances its interactions with anions. For the ion containing the aromatic ring enriched in electrons, namely [NH₂-B15C5 + Cu + ClO₄]⁺ where NH₂-B15C5 = 3-amino-benzo-15-crown-5, the opposite situation has been observed. Because of Anion-π repulsion the loss of X^· radical proceeds more readily for [NH₂-B15C5 + Cu + X]⁺ than for [B15C5 + Cu + X]⁺. Iron reduction has also been found to be affected by Anion-π interactions. Namely, the loss of CH₃O^· radical from the ion [B15C5 + Fe + NO₃ + CH₃O]⁺ proceeds more readily than from [NO₂⁻B15C5 + Fe + NO₃ + CH₃O]⁺.     

Synthesis of alkynylbenzo-15-crown-5 ethers

Reactions of 4"-iodobenzo-15-crown-5 ether with ethynylarenes or 4"-ethynylbenzo-15-crown-5 ether with haloarenes in the presence of catalytic amounts of Pd^IIcomplex salts, CuI, and Et₃N gave 4"-(arylethynyl)benzo-15-crown-5 ethers in 55—80% yields.     

Synthesis of Double-Armed Benzo-15-crown-5 and Their Complexation Thermodynamics with Alkali Cations

A series of double-armed benzo-15-crown-5 lariats (3–8) have been synthesized by the reaction of 4′, 5′-bis(bromomethyl)-benzo-15-crown-5 (2) with 4-hydroxybenzaldehyde, phenol, 4-chlorophenol, 4-methoxyphenol, 2-hydroxybenzaldehyde, and 4-acetamidophenol in 43 ~ 82% yields, respectively. The complex stability constants (K _S) and thermodynamic parameters for the stoichiometric 1:1 and/or 1:2 complexes of benzo-15-crown-5 1 and double-armed crown ethers 3–8 with alkali cations (Na⁺, K⁺, Rb⁺) have been determined in methanol–water (V/V=8:2) at 25 °C by means of microcalorimetric titrations. As compared with the parent benzo-15-crown-5 1, double-armed crown ethers 3–8 show unremarkable changes in the complex stability constants upon complexation with Na⁺, but present significantly enhanced binding ability toward cations larger than the crown cavity by the secondly sandwich complexation. Thermodynamically, the sandwich complexations of crown ethers 3-8 with cations are mostly enthalpy-driven processes accompanied with a moderate entropy loss. The binding ability and selectivity of cations by the double-armed crown ethers are discussed from the viewpoints of the electron density, additional binding site, softness, spatial arrangement, and especially the cooperative binding of two crown ether molecules toward one metal ion.     

Synthesis of Double-Armed Benzo-15-crown-5 and Their Complexation Thermodynamics with Alkali Cations

A series of double-armed benzo-15-crown-5 lariats (3–8) have been synthesized by the reaction of 4′, 5′-bis(bromomethyl)-benzo-15-crown-5 (2) with 4-hydroxybenzaldehyde, phenol, 4-chlorophenol, 4-methoxyphenol, 2-hydroxybenzaldehyde, and 4-acetamidophenol in 43 ~ 82% yields, respectively. The complex stability constants (K _S) and thermodynamic parameters for the stoichiometric 1:1 and/or 1:2 complexes of benzo-15-crown-5 1 and double-armed crown ethers 3–8 with alkali cations (Na⁺, K⁺, Rb⁺) have been determined in methanol–water (V/V=8:2) at 25 °C by means of microcalorimetric titrations. As compared with the parent benzo-15-crown-5 1, double-armed crown ethers 3–8 show unremarkable changes in the complex stability constants upon complexation with Na⁺, but present significantly enhanced binding ability toward cations larger than the crown cavity by the secondly sandwich complexation. Thermodynamically, the sandwich complexations of crown ethers 3-8 with cations are mostly enthalpy-driven processes accompanied with a moderate entropy loss. The binding ability and selectivity of cations by the double-armed crown ethers are discussed from the viewpoints of the electron density, additional binding site, softness, spatial arrangement, and especially the cooperative binding of two crown ether molecules toward one metal ion.Graphical Abstract Synthesis of Double-Armed Benzo-15-crown-5 and Their Complexation Thermodynamics with Alkali CationsYU LIU*, JIAN-RONG HAN, ZHONG-YU DUAN and HENG-YI ZHANG This revised version was published online in July 2005 with a corrected issue number.     

f-Element/crown ether complexes: 21. Conformational changes in metal complexed versus hydrogen bonded benzo-15-crown-5 in the structure of [Y(OH2)3(NCMe)-(benzo-15-crown-5)][ClO4]3·benzo-15-crown-5·CH3CN

Crystalline [Y(OH₂)₃(NCMe)(benzo-15-crown-5)][ClO₄]₃·benzo-15-crown-5-CH₃CN can be obtained by slowly cooling a reaction mixture of Y(ClO₄)₃·n H₂O with benzo-15-crown-5 in a solution of acetonitrile and methanol (3 : 1) from 60°C to room temperature. The crystal structure of this complex has been determined at –150 and 20°C. The complex is triclinic,P . At –150°C the cell parameters area = 11.986(4),b = 12.071(7),c = 16.364(5) Å, = 93.56(3), = 98.68(3), = 109.68(4)°, vol = 2187 ų, andD _calc = 1.61 g cm^–3 forZ = 2 formula units. 3633 independently observed [F _o 5(F _o)] reflections were used in the final least-squares refinement leading to an agreement index ofR = 0.048. The Y(III) ion coordination geometry approximates a tricapped trigonal prism with three water molecules and three benzo-15-crown-5 oxygen atoms forming the prism, with the two remaining benzo-15-crown-5 oxygen atoms and the acetonitrile molecule completing the coordination as capping atoms. The three water molecules hydrogen bond a second crown ether molecule and two of the perchlorate anions. The two acetonitrile molecules have contacts with perchlorate oxygen atoms close enough for some weak interaction. One perchlorate is ordered, one is partially disordered as is the coordinated solvent molecule, and the third anion is totally disordered. The two unique crown ether molecules have distinctively different conformations.For Part 20, see reference [1].     

New reaction of benzocrown derivatives of 5-amino-4-imidazolecarboxamides leading to condensed tetracyclic systems

A new cyclization reaction has been described for 5-amino-4-imidazolecarboxamides containing a benzocrown ether fragment at N₍₁₎ by the action of nitrous acid, which proceeds at the amino group of the imidazole ring and benzene ring of the macroheterocyclic fragment instead of the expected closure of the triazine ring to give a 2-azapurine analog, namely, 1-R-imidazo[4,5-d]triazin-4-one, where R is the benzo-12-crown-4 or benzo-15-crown-5 residue.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1349–1352, October, 1993.     

A Polarographic Study on Some Complexes of Pb2+ and Cd2+ with Macrocyclic Polyethers (Crown Ethers)

Abstract

Complexation constants of Pb²⁺ and Cd²⁺ nitrates with five crown compounds (18-crown-6, dicyclohexyl-18-crown-6, benzo-15-crown-5, dibenzo-24-crown-8 and 12-crown-4), have been determined by d.c. and a.c. polarographic measurements in aqueous medium using 0.1 M HNO₃ as supporting electrolyte. The complexes of lead with 18-crown-6 and dicyclohexyl-18-crown-6 are very stable which may be attributed to the partially covalent bonds formed by this metal ion.     

The X-ray structure of the trichlorocuprate of naphtho-15-crown-5 complexed potassium

The structure of the trichlorocuprate of naphtho-15-crown-5 complexed potassium has been determined by X-ray analysis. The crystal contains the complex cations [K(naphtho-15-crown-5)₂]⁺, the anion [Cu₂Cl₆]^2– and water molecules. The full composition of the compound in the solid state is represented by the formula [K(naphtho-15-crown-5)₂]₂[Cu₂Cl₆]·nH₂O), wheren3. The sandwich type cations are similar to those found previously for potassium complexes with benzo-15-crown-5. The coordination number of potassium is equal to 10; the coordination polyhedron is a 15-crown-5. The coordination number of potassium is equal to 10; the coordination polyhedron is a pentagonal antiprism. The water molecules are disordered and occupy six symmetrically independent positions with a probability of 0.5 in the crystal. The lack of close contacts between water molecules and the remaining components enabled the treatment of the complex as a clathrate. Supplementary Data relating to this article has been deposited with the British Library as Supplementary Publication No. 82154 (20 pages).     

Two highly stable and selective solid phase microextraction fibers coated with crown ether functionalized ionic liquids by different sol–gel reaction approaches

In this work, two novel crown ether functionalized ionic liquid (FIL)-based solid phase microextraction (SPME) fibers were prepared by sol–gel technology using the synthesized 1-(trimethoxysily)propyl 3-(6′-oxo-benzo-15-crown-5 hexyl) imidazolium bis(trifluoromethanesulphonyl)imide ([TMSP(Benzo15C5)HIM][N(SO₂CF₃)₂]) and 1-allyl-3-(6′-oxo-benzo-15-crown-5 hexyl) imidazolium bis(trifluoromethanesulphonyl)imide ([A(Benzo15C5)HIM][N(SO₂CF₃)₂]) as selective stationary phases. Owing to the introduction of trimethoxysilypropyl to the imidazole cation, the [TMSP(Benzo15C5)HIM][N(SO₂CF₃)₂] could be chemically bonded to the formed sol–gel silica substrate through the hydrolysis and polycondensation reaction. Similarly, the [A(Benzo15C5)HIM][N(SO₂CF₃)₂] was able to participate in the formation of the organic–inorganic copolymer coatings through the free radical crosslinking reaction. These two fibers were determined to have “bubble-like” surface characteristics analogous to a previously prepared [A(Benzo15C5)HIM][PF₆]-based fiber. Their thermal stabilities were much higher than that of the [A(Benzo15C5)HIM][PF₆]-based coating. They were capable of withstanding temperatures as high as 400 °C without evident loss of the crown ether FILs. They also had strong solvent, acid and alkali resistance, good coating preparation reproducibility and high selectivity for medium polar to polar compounds. The high selectivity of these two fibers could be attributed to the strong ion-dipole, hydrogen bonding and π–π interactions provided by the synergetic effect of ILs and benzo-15-crown-5 functionalities. Moreover, the selectivity of these two fibers was rather different although the structures of these two crown ether FILs were very similar. This is maybe because the relative contents of the crown ether FILs chemically bonded to the organic–inorganic copolymer coatings were quite different when prepared by different sol–gel reaction approaches.     

The potentiometric determination of stability constants of macrocyclic ethers using linear regression techniques

Summary The stability constants of various stoichiometries of NaCl complexes of the macrocyclic ethers of 15-crown-5, benzo-15-crown-5, 18-crown-6 and benzo-18-crown-6 were measured by maintaining identical initial ion-ligand concentrations [A ₀ ⁺ ]=[L_o] and using the expression of the stability constant _i of a complex formation, 1/_i[L_o]^n+m–1=(1–nP)ⁿ(1–mP)^m/P where P=P_AL/[1+P_AL(m–1)]. The potentiometric measurements were carried out in water with a glass membrane electrode in a computer-ion meter system.Submitted to IUPAC, International Symposium on Macrocyclic Ligands for the Design of New Materials, 1992, Surrey, UK     

Bis-substituted benzo-15-crown-5 ethers as ion carriers in potassium ion-selective electrodes

Lipophilic bis-substituted ester and ether derivatives of benzo-15-crown-5 have been synthesised. The correlation between the structure and potentiometric ion-selectivity has been studied in PVC membrane ion-selective electrodes. An ion-selective potassium sensitive electrode based on 4,5-bis (biphenyloxymethyl)benzo-15-crown-5 exhibited the best electrode properties. The detection limit was loga _K = -5.4; logK _K,Na ^ppot = -3.5. The effect of the lipophilicity of neutral carriers upon electrode performance has been also discussed.     

Preparation and crystal structure of a 1:4 diaqua(benzo-15-crown-5)(perchlorato-<Emphasis Type="Italic">O</Emphasis>)calcium perchlorate and diaqua(4′-nitrobenzo-15-crown-5)(perchlorato-<Emphasis Type="Italic">O</Emphasis>)calcium perchlorate solid solution

A 1:4 diaqua(benzo-15-crown-5)(perchlorato-O)calcium perchlorate and diaqua(4-nitrobenzo-15-crown-5)(perchlorato-O)calcium solid solution [Ca(ClO₄)LH₂O)₂]⁺ClO ₄ ^– [L = (B15C5)_0.2(4-NO₂-B15C5)_0.8] was prepared and studied by X-ray diffraction. The complex cation [Ca(ClO₄)L(H₂O)₂]⁺ is of the guest-host type. The coordination polyhedron of its Ca²⁺ cation is irregular, viz. a distorted prism with two different bases: pentagonal (of five ether oxygen atoms of mixed crown ligand L) and trigonal (of one oxygen atom of the anionic ligand ClO ₄ ^– and two oxygen atoms of the two water molecules). The packing of the complex cations and disordered ClO ₄ ^– anions in the crystal structure of this solid solution was determined to find that these ions are connected by hydrogen bonds into infinite three-dimensional layers.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004, pp. 1244–1249.Original Russian Text Copyright © 2004 by Chekhlov.This revised version was published online in April 2005 with a corrected cover date.     

Synthesis,characterization, and photochemistry of the supramolecules formed from chromium(III) thiocyanato anion associated with crown ethers

A series of anionic chromium(III) thiocyanato complexes with metal crown ether cations have been prepared and characterized. These complexes have the form [Crown-M]₂⁺[Cr(NCS)₅(H₂O)]²⁻ and [Crown-M]₃⁺[Cr(NCS)₆]³⁻, where M=Na⁺, K⁺, or NH₄⁺ and crown represents the crown ether. The crown ethers are 15-crown-5, B-15-crown-5, 18-crown-6, DB-18-crown-6, and DB-24-crown-8, where B- and DB- stand for benzo- and dibenzo-, respectively. The complexes are stable for at least 20 h in the dark in dimethylformamide(DMF) or in acetonitrile, and they release thiocyanate slowly, k=(0.71–2.67)×10⁻⁹ mol/(L s) in acetonitrile in the dark. Photoanation of thiocyanate was observed for the complexes in DMF and in acetonitrile. The quantum yields of thiocyanate release in DMF and in acetonitrile are reported. The quantum yields were in the range 0.05 to 0.52 mol einstein⁻¹ and were solvent and wavelength dependent. In general, larger quantum yields were observed in DMF than in acetonitrile. The photoreaction mechanism is discussed.     

Crown ether-facilitated transfers of alkali metal ions across the water-nitrobenzene interface

The transfer of Li⁺, Na⁺, K⁺ and Cs⁺ from water to nitrobenzene at their interface as facilitated by benzo-12-crown-4, benzo-15-crown-5, 4′-methylbenzo-15-crown-5 and benzo-18-crown-6 was studied by cyclic voltammetry. The mechanism of the transfer process was discussed and the stability constants of the complexes formed in nitrobenzene were determined.     

COMPETITIVE NMR STUDY OF THE COMPLEXATION OF SOME ALKALINE EARTH AND TRANSITION METAL IONS WITH 12-CROWN-4, 15-CROWN-5 AND BENZO-15-CROWN-5 IN ACETONITRILE SOLUTION USING THE LITHIUM-7 NUCLEUS AS A PROBE

Abstract

⁷Lithium NMR measurements were used to determine the stoichiometry and stability of Li⁺ complexes with 12-crown-4, 15-crown-5 and benzo-15-crown-5 in acetonitrile solution. A competitive ⁷Li NMR technique was also employed to probe the complexation of Mg²⁺, Ca²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺ and Cd²⁺ ions with the same crown ethers. In all cases, the stability of the resulting 1:1 complexes was found to decrease in the order 15-crown-5 > benzo-15-crown-5 > 12-crown-4. Ca²⁺ and Cd²⁺ ions formed the most stable complexes in the series.     

Potentiometric study of complexation of phenylaza-15-crown-5, 4-nitrobenzo-15-crown-5 and dibenzopyridino-18-crown-6 and other derivative of 18-crowns-6 with Na+ ion in methanol

The complexation reaction of phenylaza-15-crown-5, and 4-nitrobenzo-15-crown-5, benzo-15-crown-5 and dibenzopyrdino-18-crwon-6, dibenzo-18-crown-6,dicyclohexyl-18-crown-6(cis and trans), and 18-crown-6 with Na⁺ ion in methanol have been studied by potentiometric method. The Na⁺ ion-selective electrode has been used both as indicator and reference electrode. The stoichiometry and stability constants of complexes of these crown ethers with sodium ion were evaluated by MINIQUAD program. The major trend of stability of resulting complexes of these macrocycle with Na⁺ ion varied in the order DCY18C6 > DB18C6 > 18C6 > DBPY18C6 > phenylaza-15C5 > benzo-15C5 > 4-nitrobenzo-15C5. The obtained results in particular stability constant of complexes of DBPY18C6, phenylaza-15C5 and 4-nitrobenzo-15C5 with sodium ion in comparison with other crowns ether are novel, and interesting.     

Crown Ether As The Phase-Transfer Catalyst for Free Radical Polymerization of Hydrophobic Vinyl Monomers

Various crown ethers were used as phase-transfer catalysts for free radical polymerizations of some water-insoluble vinyl monomers such as acrylonitrile, methylmethacrylate and styrene with persulfate as initiator. The catalytic abilities of these crown ethers for free radical polymerization of acrylonitrile with S₂O₈^2?ion as an initiator were in the order: 18-crown-6 > 15-crown-4 > 12-crown-4 > benzo-15-crown-5 > dibenzo-18-crown-6. Among various persulfates such as Na₂S₂O₈ K₂S₂O₈ and (NH₄)₂S₂O₈, ammonium persulfate was the optimum initiator for the polymerization of acrylonitrile catalyzed by 18-crown-6 or 15-crown-5. Among the organic solvents used, chloroform seems to be the best solvent for the catalytic polymerization of acrylonitrile. An apparent activation energy of 72.9 kJ mol^?1 was observed for the polymerization of acrylonitrile. The catalytic reaction rates of free radical polymerization for these hydrophobic vinyl monomers were in the order: acrylonitrile > methylmethacrylate > styrene > isoprene. Effects of concentrations of crown ether, initiator, and nitrogen on the polymerization of these vinyl monomers were investigated.