Synthesis of Bis(2,2-benzimidazolyl)dibenzo-18-crown-6

A method has been developed for the introduction of benzimidazole substituents into the dibenzo-18-crown-6 molecule by condensation of its 4′,4″(5″)-diacetyl derivative with ortho-phenylenediamine. Increasing the length of the hydrocarbon chain of the acyl substituent or replacing Ac by CSNH₂ led to a decrease in the yield of the desired product. No product was formed when Ac was replaced by COOH or CN. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, 1388–1390, September, 2005.     

Crystal Structure of 1,10-Diazonia-18-crown-6 Bis(DL-glutamate)

The crystal structure of 1'10-diazonia-18-crown-6 bis(DL-glutamate) was studied by single crystalX-ray diffraction. The geometries of molecular ions, their packing in the crystal lattice were determined.The macrocyclic dication is located around the crystallographic inversion center i(000) and has an unusual, previously unknown conformation. The crystalline salt forms an infinite three-dimensional polymeric network linked by interionic hydrogen bonds and coulombic interactions of molecular ions.     

Crystal Structure of 1,10-Diazonia-18-crown-6 Bis(hydrogen oxalate) and 1,10-Diazonia-18-crown-6 Oxalate Dihydrate

An X-ray diffraction study has been performed to study the crystal structure of 1,10-diazonia-18-crown-6 bis(hydrogen oxalate) [H₂DA18C6]²⁺·2C₂HO ₄ ^- (I) and 1,10-diazonia-18-crown-6 oxalate dihydrate [H₂DA18C6]²⁺·2C₂O ₄ ^- ·2H₂O (II). Crystals I are triclinic: space group , a = 7.825, b = 7.861, c = 9.349 , = 97.28, = 110.22, = 99.12°, Z = 1. Crystals II are monoclinic: space group P2 ₁ /n, a = 8.783, b = 10.640, c = 10.225 , = 97.04°, Z = 2. The structures of I and II were solved by direct methods and refined by the full-matrix least-squares procedure anisotropically to R = 0.036 (I) and 0.042 (II) for all 2206 (I) and 1990 (II) unique reflections measured (CAD-4 automatic diffractometer, CuK ). In the crystal structures, the ionic complexes (salts) I and II are not individual guest–host complex molecules but are parts of complex (infinite in two directions) three-dimensional layers of H-bonded molecular anions and DA18C6 dications (and water molecules in II). In structures I and II, the centrosymmetric DA18C6 dications have different conformations: two-angle in I and four-angle in II. The unusual four-angle conformation of the DA18C6 dication was found for the first time.     

Synthesis and crystal structure of aqua(dibenzo-18-crown-6)potassium (dibenzo-18-crown-6)(perchlorato-O)potassium perchlorate

A new compound, aqua(dibenzo-18-crown-6)potassium (dibenzo-18-crown-6)(perchlorato-O)potassium perchlorate ([K(DB18C6)(H₂O)]⁺ · [K(ClO₄)(DB18C6)] · ClO ₄ ^? ; compound I) is synthesized and studied by X-ray crystallography. The crystals are triclinic: a = 9.050 Å, b = 9.848 Å, c = 26.484 Å, α = 82.87°, β = 84.16°, γ = 77.93°, Z = 2, space group P $\bar 1$ . The structure is solved by a direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.058 for 5960 independent reflections (CAD4 diffractometer, λMoK _α radiation). A complex cation [K(DB18C6)(H₂O)]⁺ and a complex molecule [K(ClO₄)(DB18C6)] are of the host-guest type; they are linked into a dimer through two K⁺ → π(C) bonds formed by one of the two K⁺ cations with two C atoms of the benzene ring of the DB18C6 ligand from the adjacent complex. Both DB18C6 ligands in I have a butterfly conformation with approximate symmetry C _2v .     

Synthesis and crystal structure of aqua(dibenzo-18-crown-6)potassium (dibenzo-18-crown-6)-(tetrachlorocuprato(II)-Cl)potassium

New mixed complex compound aqua(dibenzo-18-crown-6)potassium (dibenzo-18-crown-6)(tetrachlorocuprato(II)-Cl)potassium, [K(CuCl₄)(Db18C6)]^? · [K(Db18C6)(H₂O)]⁺, is synthesized and its crystal structure is studied by the method of x-ray structural analysis. The structure includes two independent complex ions, both of guest-host type: two cations K⁺ are located in the respective cavities of the Db18C6 crown-ligand (one in each) and each is coordinated by all its six O atoms and one Cl atom of the anion-ligand [CuCl₄]^2? or O atom of the ligand water molecule. Coordination of these two K⁺ cations is completed to hexagonal pyramidal one by formation by each of unusually weak coordination bond K⁺ → π(\(C\dddot - C\)) with two C atoms of respective benzene ring in the neighboring Db18C6 ligand. In this crystal structure the complex anions and cations form dual infinite chains via these coordination bonds and interionic O-H?Cl hydrogen bonds.     

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.     

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.     

On the protonation of dibenzo-18-crown-6

Abstract  

The stability constant of the dibenzo-18-crown-6·H₃O⁺ cationic complex species dissolved in nitrobenzene saturated with water has been determined from extraction experiments in the two-phase water–nitrobenzene system and from γ-activity measurements. Various structures of protonated dibenzo-18-crown-6 are discussed.     

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.     

Synthesis and crystal structure of ammonium (picrate) (dibenzo-18-crown-6)

NH₄(Pic)(DB18C6) (Pic=picrate and DB18C6=dibenzo-18-crown-6), (C₂₆H₃₀N₄O₁₃) FW 606.56, arthorhombic,Pmn2₁,a=26.045(5),b=12.055(3),c=8.982(3) Å,V=2820(1) ų,Z=4,D _c =1.429 g/cm³, CuK, =1.54184 Å, (CuK)=9.5 cm^–1,F(000)=1272,T=298 K. The structure has been refined toR=0.0475 for 2617 unique observed reflections. In the lattice the 1:1 complex exists as a 2:2 dimer in which the crown are coupled through the Pic anions and NH₄ ⁺ cations. The asymmetric unit consists of two independent half crown ethers of which two opposite O atoms are on the mirror plane, two half ammonium cations of which the N and two H atoms are also on the mirror plane while the Pic anion is in a general position. Relative to each other, the corwn ethers are shifted by about 7.3 Å alongb and 1 Å alongc. The 1:1 sandwich of NH₄ with DB18C6 and Pic on dimerisation becomes a club pseudo-sandwich with three phenyl rings on either side of the mirror plane, thus forming a nearly parallel stack with a 3.6 Å inter-ring distance. The NH₄ ions hold the structure; two H atoms on the mirror plane are hydrogen-bonded to the opposite oxygens of the crown located on the purely aliphatic part of the ring (2.10(1), 2.06(3) and 2.26(3), 2.05(1) Å) for the two independent crowns, respectively, while the other two H atoms form mirror-related bifurcated hydrogen bonds with the phenoxide oxygen (1.99(1) and 2.01(1) Å) and theo-nitrogen oxygen (2.44(2) and 2.34(1) Å) of the picrates. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82037 (29 pages)     

On the protonation of dibenzo-18-crown-6

Abstract  The stability constant of the dibenzo-18-crown-6·H₃O⁺ cationic complex species dissolved in nitrobenzene saturated with water has been determined from extraction experiments in the two-phase water–nitrobenzene system and from γ-activity measurements. Various structures of protonated dibenzo-18-crown-6 are discussed. Graphical abstract        

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.