We describe a facile synthesis of the cyapho-cyanamide salt [Na(18-crown-6)][N(CN)(CP)] from reaction [Na(18-crown-6)][PH2] (18-crown-6=1,4,7,10,13,16-hexaoxacyclooctadecane) with dimethyl N-cyanocarbonimidate, (MeO)2C=N(CN). The proceeds elimination two equivalents methanol. Careful tuning conditions allowed for isolation and characterization N-cyano(carboximidate)phosphide intermediate [HP{C(...

the complexation reactions between tl+ and pb2+ ions and crown ethers 12-crown-4(12c4), 15-crown-5 (15c5), benzo-15-crown-5 (b15c5), 18-crown-6 (18c6), dicyclohexyl-18-crown-6 (dc18c6) and aza-18-crown-6 (a18c6) were studied in 90% acetonitrile and 90% ethanol solutions at 25 °c, using an a.c. polarographic technique. the stoichiometry and stability of the complexes were determined by monitorin...

Deltahedral nine-atom clusters of silicon, Si(9)(2-), were synthesized by mild oxidation of a liquid ammonia solution of K(12)Si(17) with Ph(3)GeCl in the presence of 18-crown-6 (1,4,7,10,13,16-hexaoxacyclooctadecane) or 2,2,2-crypt (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane). The clusters were structurally characterized in [K(18-crown-6)](2)Si(9).C(5)H(5)N (yellow; orthorhombi...

A novel synergistic extraction system was investigated for the possible selective separation of light lanthanoids using an ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, as an extraction solvent and 2-thenoyltrifluoroacetone and 18-crown-6 as extractants. Trivalent lanthanum was efficiently extracted as a cationic ternary complex by the cation-exchange process, wh...

The stoicheiometrically 1:1 adduct of 1,4,7,10,13,16-hexaoxa-cyclooctadecane with m-nitroaniline, C18H30N2O8, Mr = 402.45, crystallises from toluene in red-orange prisms, (probable) space group P i , a = 801.8(3), b = 920.4(3), c = 1403.3(4) pm, a = 80.40(4), ß = 79.79(4), y = 85.95(3)°, V = 1.07910 nm3, Z = 2, dcaic. = 1.238 Mgm~3. Structure refinement converged at R = 0.060 (Rw = 0.002) for 2...

Novel dual-pipet electrodes prepared by pulling borosilicate theta-tubing are described. Three types of electrochemical experiments employing such devices include the following: (1) generation/collection experiments in which ions are ejected from one of two micropipets ("generator") into the external solution and collected at the second pipet ("collector"), (2) measurements of ohmic current-vol...

Molecular-dynamics simulations of crystalline 18crown-6 have been performed in a study of the apparent thermal shortening of covalent bonds observed in crystal structures. At 100 K, a shortening of 0.006 _+ 0.001 A for C----C and C----O bonds was obtained. This result was found to be independent of details of the force field and the simulation. There was agreement between computational and expe...

A simple and sensitive extraction-spectrophotometric method for rapid and accurate determination of benzocaine in pure and dosage forms was developed. Benzocaine was effectively extracted as a 1:1 ion pair complex with dicyclohexyl18-crown-6 and calmagite in acidic media into chloroform, followed by spectrophotometric determination at 486 nm. Molar absorptivity of the ternary complex at this wa...

Single-crystals X-ray structure analysis of very thermally labile and moisture sensitive ammoniate crystals of [K0.28Rb7.72Si9Ni(CO)2]2·16NH3 show the presence of the very rarely observed nickel-silicide complex [{Ni(CO)2}2(μ-Si9)2]8−, which was up to now only known in the 18-crown-6 involving solid [Rb@18-crown-6)]2[K@18-crown6)]2Rb4[{Ni(CO)2}2(μ-Si9)2]·22NH3. This shows that, like already kno...

The title compound, C(2)H(2)·C(12)H(24)O(6)·2NH(3), was formed by co-crystallization of 18-crown-6 and acetyl-ene in liquid ammonia. The 18-crown-6 mol-ecule has threefold rotoinversion symmetry. The acteylene mol-ecule lies on the threefold axis and the whole mol-ecule is generated by an inversion center. The two ammonia mol-ecules are also located on the threefold axis and are related by inve...