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Showing papers on "Iodide published in 2000"


Journal ArticleDOI
TL;DR: The formation of Iodo-trihalomethanes (I-THMs) such as Iodoform (CHI3) during oxidative treatment of iodide-containing drinking waters can be responsible for taste and odor problems as discussed by the authors.
Abstract: The formation of iodo-trihalomethanes (I-THMs) such as iodoform (CHI3) during oxidative treatment of iodide-containing drinking waters can be responsible for taste and odor problems. I-THMs are formed by reactions of hypoiodous acid (HOI) with natural organic matter. HOI is quickly formed from naturally occurring iodide (I-) by oxidation with ozone, chlorine, or chloramine. The kinetics of reactions of HOI with organic model compounds as well as the resulting CHI3 formation were measured. Substituted phenols, phenol, and, to a smaller extent, α-methyl carbonyl compounds were found to be reactive toward HOI and also to yield CHI3. Resorcinol (m-hydroxyphenol) had the highest yield of CHI3. The kinetics of I-THM formation were also measured in natural waters which were oxidatively treated with ozone, chlorine, or chloramine. When ozone was used, no I-THMs were detected and ≥90% of I- was transformed to IO3-. Chlorine led to the formation of both IO3- and I-THMs. With increasing chlorine doses, the CHI3 form...

354 citations


Journal ArticleDOI
TL;DR: In this article, a flash photolysis in propylene carbonate was performed to measure the reaction rate of a dye-sensitized titanium dioxide mesoporous electrodes in photoelectrochemical energy conversion devices.
Abstract: Specific adsorption of cations (H+, Li+, ...) on TiO2 nanocrystalline particles is known to control the energetics of the conduction band and therefore the ability for molecular sensitizers to inject electrons into the semiconductor upon irradiation. In photoelectrochemical energy conversion devices employing dye-sensitized titanium dioxide mesoporous electrodes, back electron transfer is generally intercepted by the use of the iodide/triiodide couple as a charge mediator. Kinetics of the oxidation of I- by the oxidized state of cis-RuII(dcbpy)2(NCS)2 sensitizer adsorbed on TiO2 was measured by flash photolysis in propylene carbonate. The rate of this reaction was found to depend on the nature and concentration of added cations such as Mg2+, Li+, Na+, and K+. A brusque acceleration of the process was in particular observed at a critical concentration. Electrophoretic measurements showed that this step in the dye regeneration reaction kinetics corresponds to the reversal of particle surface charge upon ads...

341 citations


Journal ArticleDOI
TL;DR: In this article, two distinct classes of promoters were identified for the reaction: simple iodide complexes of zinc, cadmium, mercury, indium and gallium and carbonyl complexes of tungsten, rhenium, ruthenium and osmium.

303 citations



Journal ArticleDOI
TL;DR: In this paper, the authors used a gold amalgam (Au/Hg) voltammetric microelectrode to measure the distributions of O 2, Mn(II), Fe(II, I(2I), I (2I) and HS(2) in bioturbated sediment cores from the Laurentian Trough.

173 citations


Journal ArticleDOI
TL;DR: Thyroid cells treated with iodide excess underwent apoptosis, as evidenced by morphological changes, plasma membrane phosphatidylserine exposure, and DNA fragmentation, whereas inhibition of peroxidase enzymatic activity by propylthiouracil completely blocked iodide cytotoxicity.
Abstract: Thyroid toxicity of iodide excess has been demonstrated in animals fed with an iodide-rich diet; in vitro iodide is cytotoxic, inhibits cell growth, and induces morphological changes in thyroid cells of some species. In this study, we investigated the effect of iodide excess in an immortalized thyroid cell line (TAD-2) in primary cultures of human thyroid cells and in cells of nonthyroid origin. Iodide displayed a dose-dependent cytotoxicity in both TAD-2 and primary thyroid cells, although at different concentrations, whereas it had no effect on cells of nonthyroid origin. Thyroid cells treated with iodide excess underwent apoptosis, as evidenced by morphological changes, plasma membrane phosphatidylserine exposure, and DNA fragmentation. Apoptosis was unaffected by protein synthesis inhibition, whereas inhibition of peroxidase enzymatic activity by propylthiouracil completely blocked iodide cytotoxicity. During KI treatment, reactive oxygen species were produced, and lipid peroxide levels increased mark...

153 citations


Journal ArticleDOI
TL;DR: Palladium-catalyzed cross-coupling of aryl- or alkenylsilanols, silanediols, and silanetriols with a variety of iodoarenes by the catalysis of palladium(0) and in the presence of silver(I) oxide furnished the coupling products in good to excellent yields.
Abstract: Palladium-catalyzed cross-coupling of aryl- or alkenylsilanols, silanediols, and silanetriols with a variety of iodoarenes by the catalysis of palladium(0) and in the presence of silver(I) oxide furnished the coupling products in good to excellent yields. The reactions of silanediols or silanetriols under similar conditions proceeded much faster than those of silanols to afford the corresponding coupling products in excellent yields within shorter reaction periods (5−12 h). The measurement of the X-ray diffraction (XRD) pattern of the silver residue after the reaction revealed that silver(I) oxide was converted to silver(I) iodide.

152 citations


Journal ArticleDOI
TL;DR: In this paper, a microwaveenhanced, solventless Sonogashira coupling reaction has been developed, where terminal alkynes couple with aryl or alkenyl iodide on palladium-doped alumina to provide high yields of products.

129 citations


Journal ArticleDOI
13 Apr 2000-Langmuir
TL;DR: In this paper, the interaction of iodide ions with cuprite (Cu2O) surfaces was studied by combining batch experiments and surface analyses, and it was shown that two different pH-dependent mechanisms are responsible for the accumulation of the iodide species on Cu2O.
Abstract: The interactions of iodide ions with cuprite (Cu2O) surfaces were studied by combining batch experiments and surface analyses. The evolution of iodide uptake with pH was investigated. The thermodynamical calculations and surface analyses (X-ray photoelectron spectroscopy, scanning electron microscopy, Raman spectroscopy, and electrochemistry) were used to show that two different pH-dependent mechanisms are responsible for the accumulation of the iodide species on Cu2O. At pH values lower than 6.5, the precipitation of CuI occurs on the cuprite surface, while in more alkaline medium, the iodide adsorption takes place by substituting the surface hydroxyl groups of Cu2O. The sorption processes were not affected by a 1000-fold excess of chloride ions, but they were limited to the potential range corresponding to the stability domain of Cu2O (i.e., between −10 and +190 mV/ENH at pH 8); thus no accumulation was observed either on metallic copper or on CuO.

126 citations


Journal ArticleDOI
TL;DR: Reaction of silver(I) trifluoromethanethiolate (AgSCF(3) with KI or tetra-n-butylammonium iodide in acetonitrile leads to the formation of a nucleophilic source of trif fluoro-, chloro-, bromo-, and iodoaromatics under mild conditions.
Abstract: Reaction of silver(I) trifluoromethanethiolate (AgSCF3) with KI or tetra-n-butylammonium iodide in acetonitrile leads to the formation of a nucleophilic source of trifluoromethanethiolate. This source is capable of converting activated fluoro-, chloro-, bromo-, and iodoaromatics into the corresponding trifluoromethyl aryl sulfides under mild conditions. After successful reaction with tetra-n-butylammonium iodide, crystals of Bu4N[Ag3I4] precipitate from the reaction mixture. With less activated aromatic compounds, decomposition of the trifluoromethanethiolate anion occurs preferentially, giving bis(trifluoromethyl)disulfide, tetrakis(trifluoromethylthio)ethene, and 3,4,5,6-tetrakis(trifluoromethylthio)-1,2-dithiine. The use of copper(I) trifluoromethanethiolate and mercury(II) trifluoromethanethiolate for such reactions has also been investigated.

113 citations


Journal ArticleDOI
TL;DR: In this paper, transient kinetic measurements of the formation of compound I of human eosinophil peroxidase (EPO) and its reaction with halides and thiocyanate, using the sequential-mixing stopped-flow technique, were presented.
Abstract: Compound I of peroxidases takes part in both the peroxidation and the halogenation reaction. This study for the first time presents transient kinetic measurements of the formation of compound I of human eosinophil peroxidase (EPO) and its reaction with halides and thiocyanate, using the sequential-mixing stopped-flow technique. Addition of 1 equiv of hydrogen peroxide to native EPO leads to complete formation of compound I. At pH 7 and 15 °C, the apparent second-order rate constant is (4.3 ± 0.4) × 107 M-1 s-1. The rate for compound I formation by hypochlorous acid is (5.6 ± 0.7) × 107 M-1 s-1. EPO compound I is unstable and decays to a stable intermediate with a compound II-like spectrum. At pH 7, the two-electron reduction of compound I to the native enzyme by thiocyanate has a second-order rate constant of (1.0 ± 0.5) × 108 M-1 s-1. Iodide [(9.3 ± 0.7) × 107 M-1 s-1] is shown to be a better electron donor than bromide [(1.9 ± 0.1) × 107 M-1 s-1], whereas chloride oxidation by EPO compound I is extremel...

Journal Article
TL;DR: The preliminary data indicate that NIS-based gene therapy may be applied by concentrating a lethal dose of radiation in tumor cells in vivo, but further investigation is necessary to determine a method of maintaining radioiodine in the cells to allow greater therapeutic effects.
Abstract: 131I therapy is a widely accepted treatment for metastatic differentiated thyroid cancer. To investigate the feasibility of 131I therapy for breast cancer, we established breast cancer cells stably expressing Na+/I− symporter (NIS) gene that can be modulated and studied in vitro and in vivo. Methods: We transfected rat NIS genes into a human breast cancer cell line (MCF7) by electroporation. Iodide accumulation was evaluated under various extracellular concentrations of sodium and iodide, and iodide efflux was also assessed. Biodistribution and tumor imaging were studied using tumor-bearing mice. Results: A novel cell line (MCF3B), stably expressing the NIS gene, was established from MCF7. MCF3B took up 44 times more radioiodide in vitro than MCF7 did. Iodide uptake was completely inhibited by 1 mmol/L perchlorate and was dependent on external sodium and iodide concentrations. Iodide efflux from MCF3B cells was slower (half-life [T1/2] > 27 min) than from FRTL5 thyroid cells (T1/2 = 4 min). In the biodistribution study using MCF3B-xenografted mice, high tumor uptake of 125I was shown (16.73%) at 1 h after injection, and tumor-to-normal tissue ratios were also high (4.84–21.28), except in the stomach (0.47). However, the iodide accumulation in the tumor lessened with time, reaching less than 1% at 24 h after injection. Conclusion: Our preliminary data indicate that NIS-based gene therapy may be applied by concentrating a lethal dose of radiation in tumor cells in vivo, but further investigation is necessary to determine a method of maintaining radioiodine in the cells to allow greater therapeutic effects.

Journal ArticleDOI
21 Oct 2000-Langmuir
TL;DR: In this article, a detailed analysis of the O−H stretching mode of cellulose acetate films dyed with pseudoisocyanine iodide (1, 1'-diethyl-2, 2,2'-cyanine iodides) has been performed and their structures characterized by FTIR spectroscopy.
Abstract: Cellulose acetate films dyed with pseudoisocyanine iodide (1,1'-diethyl-2,2'-cyanine iodide) have been produced by spin coating and their structures characterized by FTIR spectroscopy. The aggregation of the cyanine during the spinning process was induced by addition of KI to the precursor solution, and the formation of J-aggregates was observed by UV−vis spectroscopy. The detailed analysis of the O−H stretching mode of cellulose acetate allowed us to understand the types of hydrogen bonds existing in the pure matrix films, in films containing just cyanine monomers and J-aggregates as well. It has been shown that cyanine monomers, even in a large concentration, have a small influence on the cellulose acetate structure, by favoring the replacement of some intermolecular by intramolecular hydrogen bonds. On the contrary, the presence of cyanine J-aggregates remarkably modifies the arrangement of the polymer chains, inducing an extensive formation of intermolecular hydrogen bonds in the C2, C3, and/or C6 pos...

Journal ArticleDOI
TL;DR: In this article, the separation of different fractions of humic substances by their molecular weight was carried out by size exclusion chromatography (SEC) and the fixation of inorganic iodide by HS of these fraction...
Abstract: Separation of different fractions of humic substances (HS) by their molecular weight was carried out by size exclusion chromatography (SEC). The fixation of inorganic iodide by HS of these fraction...

Journal ArticleDOI
TL;DR: In this paper, the properties of poly(3,4-ethylenedioxythiophene) (PEDT) film have been studied in iodide solutions by cyclic voltammetry and stripping voltammetric methods.

Journal ArticleDOI
TL;DR: A six-step synthesis of (±)-steganone from commercially available 3,4,5-trimethoxybenzyl alcohol features a samarium(II) iodide promoted 8-endo ketyl−olefin coupling to install, in a single transformation, the 8,5 ring system common to the lignan lactones as mentioned in this paper.
Abstract: A six-step synthesis of (±)-steganone from commercially available 3,4,5-trimethoxybenzyl alcohol features a samarium(II) iodide promoted 8-endo ketyl−olefin coupling to install, in a single transformation, the 8,5 ring system common to the lignan lactones. The racemic synthesis provided the basis for the construction of (−)-steganone, which exploited a chromium tricarbonyl moiety both to establish and protect the desired absolute stereochemistry through key transformations, including a SmI2-promoted 8-endo radical cyclization and two palladium-catalyzed couplings.

Journal ArticleDOI
TL;DR: Iodide uptake by the sodium/iodide symporter in thyrocytes is essential for thyroid hormone production and Polarized functions, such as iodide efflux into follicular lumina, may also contribute to the increased iodide concentration after follicle formation.
Abstract: Iodide uptake by the sodium/iodide symporter (NIS) in thyrocytes is essential for thyroid hormone production. Reduced NIS activity has been reported in thyroid diseases, including thyroid cancer and congenital hypothyroidism. The study of iodide uptake in thyrocytes has been limited by the availability of appropriate in vitro models. A new culture technique was recently developed that allows normal human thyroid primary culture cells to grow as monolayer cells and express differentiated functions for more than 3 months. We used this technique to study the effect of follicle formation and TSH on iodide uptake in these cells. Iodide uptake by the cells grown in monolayer was very low. Follicle formation was induced from monolayer cells, and electron micrographs demonstrated cell polarity in the follicles. No significant increase in iodide uptake was observed after TSH treatment of cells in monolayer or when follicle formation was induced without TSH. TSH stimulation of follicles, however, significantly increased iodide uptake ( approximately 4. 4-fold; P<0.001). Compared with iodide uptake in monolayers, the combination of follicle formation and TSH treatment stimulated iodide uptake synergistically to 12.0-fold (P<0.001). NIS messenger RNA (mRNA) and protein levels were almost the same in both monolayer cells and follicles. TSH treatment of monolayers and follicles produced significant (P<0.05) stimulation of mRNA ( approximately 4. 8- and approximately 4.3-fold respectively) and protein ( approximately 6.8- and 4.9-fold respectively). TSH stimulated NIS protein levels in both monolayer and follicles, however, stimulation of functional iodide uptake was only seen with TSH stimulation of follicles. The function of NIS may involve post-transcriptional events, such as intracellular sorting, membrane localization of NIS or another NIS regulatory factor. Polarized functions, such as iodide efflux into follicular lumina, may also contribute to the increased iodide concentration after follicle formation.

Journal ArticleDOI
TL;DR: In this paper, the same compounds can be obtained by the non-catalytic reactions of Bu 3 SnSePh with ArN 2 BF 4 or (ArN 2 ) 2 ZnCl 4.

Journal ArticleDOI
TL;DR: Comparison of the antibacterial activity against cytotoxic effects on several human cells revealed that bis-QACs, especially 4DTBP-6,8, have wide concentration ranges showing sufficient antib bacterial activity and lower cytotoxicity effect on human cells, although benzalkonium chloride caused significant human cell damage at the concentrations necessary for antibacterial activities.

Journal ArticleDOI
TL;DR: Pd(II) complexes of phosphine−nitrogen (P−N) bidentate donors act as efficient catalysts for the Heck reaction as mentioned in this paper, achieving a turnover number of up to 106.

Journal ArticleDOI
TL;DR: The use of trifluoroacetate as an efficient and nonhygroscopic catalyst for the alcoholysis, hydrolysis, and acetolysis of epoxides was studied in this article.
Abstract: Iron(III) trifluoroacetate was used as an efficient and nonhygroscopic catalyst for the alcoholysis, hydrolysis, and acetolysis of epoxides. The addition of chloride, bromide, iodide, and nitrate ions to epoxides to produce the corresponding 2-halo and 2-nitratoalkanols and also the conversion of epoxides to acetonides and thiiranes were also performed efficiently in the presence of this catalyst.

Journal ArticleDOI
TL;DR: The first bidentate, peralkylated guanidine based ligand has been synthesized and its complexation chemistry examined by the preparation of three representative coordination compounds as mentioned in this paper.
Abstract: The first bidentate, peralkylated guanidine based ligand has been synthesized and its complexation chemistry examined by the preparation of three representative coordination compounds. The novel chelate ligand 1,3-bis(N,N,N′,N′-tetramethylguanidino)propane (btmgp, 1) has been synthesized by the reaction of N,N,N′,N′tetramethylguanidine (TMG) with 1,3-dibromopropane and subsequent deprotonation of the resulting guanidinium salt with sodium ethoxide. The bifunctional N-donor compound was treated with copper(I) iodide, copper(II) chloride and iron(II) iodide in a 1∶1 molar ratio to yield the corresponding electroneutral complexes [CuI(btmgp)] 2, [CuCl2(btmgp)] 3 and [FeI2(btmgp)] 4. The structures of the dihydrochloride of 1 (1b) and of the complexes 2–4 have been determined by X-ray crystallography. A comparison of the molecular structures (2–4) shows that, in each case, btmgp acts as a bidentate ligand which is able to stabilize not only trigonal-planar (2), but also (distorted) square-planar (3) and tetrahedral coordination environments (4).

Journal ArticleDOI
TL;DR: The present reaction provides the first example of utilizing a cadmium complex as a catalyst in enantioselective reaction, and it is shown that the chiral N,N′-dioxide–cadmium iodide complex has been shown to catalyze enantiosity conjugate additions of thiols to cyclic enones and enals.

Journal ArticleDOI
TL;DR: The first total synthesis of the oxindole alkaloid gelsedine starting from (S)-malic acid is described, which leads to the unnatural (+)-enantiomer of gelsingine in 21 steps and 0.10% overall yield.
Abstract: The first total synthesis of the oxindole alkaloid gelsedine (1) starting from (S)-malic acid is described. The key step is a novel iodide-promoted intramolecular reaction of an allene with an N-acyliminium ion intermediate which provided in a single step the bicyclic vinyl iodide 11. Other important steps are the highly stereoselective Pd-catalyzed Heck cyclization of N-methylanilide 23a which led to the desired spiro-oxindole 24a, the fully regioselective intramolecular oxymercuration of 25a to the desired cyclic ether, and the remarkable oxindole N-demethylation of 29 via a radical mechanism by using dibenzoyl peroxide. The total synthesis was concluded by the stereoselective introduction of the ethyl group from the bis-Boc compound 41 followed by methoxylation of the oxindole nitrogen. This total synthesis leads to the unnatural (+)-enantiomer of gelsedine in 21 steps and 0.10% overall yield.

Journal ArticleDOI
TL;DR: Ionic liquids derived from 1-ethyl-3methylimidazolium iodide (emimI), and aluminium chloride have been shown to be suitable solvents for the acylative cleavage of a series of cyclic and acyclic ethers as discussed by the authors.

Journal ArticleDOI
01 Jan 2000-Analyst
TL;DR: In this article, a rapid and sensitive flow method, based on the combination of online oxidation and reverse micellar mediated chemiluminescence detection, was found to be suitable for the determination of iodide in aqueous solution.
Abstract: A rapid and sensitive flow method, based on the combination of on-line oxidation–solvent extraction with reversed micellar mediated luminol chemiluminescence detection, was found to be suitable for the determination of iodide in aqueous solution. The flow procedure involved the oxidation of iodide to iodine, extraction of iodine into cyclohexane followed by membrane phase separation, and its chemiluminescence detection using the reaction of iodine with luminol in a reversed micellar solution of hexadecyltrimethylammonium chloride in 6 + 5 (v/v) chloroform–cyclohexane/water (buffered with sodium carbonate). The optimum conditions for iodide oxidation were evaluated using 2-iodosobenzoate as an oxidizing agent and a detection limit of 0.02 ng mL−1 iodide was achieved. Using different oxidants, 2-iodosobenzoate and peroxodisulfate, linear calibration graphs were obtained with dynamic ranges from 5 to 200 and from 50 to 5000 ng mL−1, respectively. The proposed method was also applied to a mixture of iodine and iodide, where iodine was determined directly without using an oxidizing agent, total iodine (iodine + iodide) was determined using an oxidizing agent, and iodide was calculated by difference. The method was applied to the differential determination of iodide and iodine in gargle samples with a precision of ca. 4% relative standard deviation.

Journal ArticleDOI
TL;DR: The ancient Chinese recognized goiter and the therapeutic effects of burnt sponge and seaweed in reducing its size or causing its disappearance, and the use of iodine in treatment and prevention of goiter was revived.
Abstract: The ancient Chinese recognized goiter and the therapeutic effects of burnt sponge and seaweed in reducing its size or causing its disappearance. The modern use of iodine in the prevention of goiter dates from 1830, when it was proposed that goiter is an iodine deficiency disease due to lack of iodine in the water supply. But unfavorable symptoms of iodism were frequent owing to overenthusiastic use and overdose of iodine. Consequently, iodide prophylaxis was discredited and abandoned. The presence of iodine in organic combination as a normal constituent of the thyroid was established in 1896 and the use of iodine in treatment and prevention of goiter was revived. In 1917 the general use of iodized salt in goitrous areas was shown to be effective in preventing simple endemic goiter.

Journal ArticleDOI
TL;DR: The antioxidant effect of 15 μm NaI has been found to be approaching the physiologically relevant concentration of ascorbic acid (50 μm), which is in accordance with previous results from in vitro depolymerization experiments with hyaluronic acid.
Abstract: Free radicals and subsequent lipid peroxidation have been implicated in the pathogenesis of several degenerative and chronic diseases which are also treated frequently in spas. There are some data arising from previous studies which support an antioxidant or scavenging effect of iodide, being the essential ingredient of a therapeutically used local brine. The aim of the study was to test the antioxidant capacity of iodide in human serum. For this reason we measured the so-called Total Antioxidant Status determined by a colorimetric method, which reflects the protection against the attack of reactive oxygen species, including enzymic and non-enzymic antioxidants. Exogenous iodide applied as NaI, shows a significantly increased antioxidant capacity in comparison with NaCl at a concentration of 15 microM, which is quite comparable to the upper range of serum iodide levels achieved through balneo-therapeutical intervention. This result is in accordance with previous results from in vitro depolymerization experiments with hyaluronic acid. The antioxidant effect of 15 microM NaI has been found to be approaching the physiologically relevant concentration of ascorbic acid (50 microM).

Journal ArticleDOI
TL;DR: It is demonstrated in dogs that the stimulatory effect of iodides is greater in thyroids deprived of iodide, raising the possibility that differences in thyroid iodide pool may account, at least in part, for the differences between the different species studied.
Abstract: The regulation of thyroid metabolism by iodide involves numerous inhibitory effects. However, in unstimulated dog thyroid slices, a small inconstant stimulatory effect of iodide on H(2)O(2) generation is observed. The only other stimulatory effect reported with iodide is on [1-(14)C]glucose oxidation, i.e., on the pentose phosphate pathway. Because we have recently demonstrated that the pentose phosphate pathway is controlled by H(2)O(2) generation, we study here the effect of iodide on basal H(2)O(2) generation in thyroid slices from several species. Our data show that in sheep, pig, bovine, and to a lesser extent dog thyroid, iodide had a stimulatory effect on H(2)O(2) generation. In horse and human thyroid, an inconstant effect was observed. We demonstrate in dogs that the stimulatory effect of iodide is greater in thyroids deprived of iodide, raising the possibility that differences in thyroid iodide pool may account, at least in part, for the differences between the different species studied. This represents the first demonstration of an activation by iodide of a specialized thyroid function. In comparison with conditions in which an inhibitory effect of iodide on H(2)O(2) generation is observed, the stimulating effect was observed for lower concentrations and for a shorter incubation time with iodide. Such a dual control of H(2)O(2) generation by iodide has the physiological interest of promoting an efficient oxidation of iodide when the substrate is provided to a deficient gland and of avoiding excessive oxidation of iodide and thus synthesis of thyroid hormones when it is in excess. The activation of H(2)O(2) generation may also explain the well described toxic effect of acute administration of iodide on iodine-depleted thyroids.

Journal ArticleDOI
TL;DR: Density functional theory calculations were performed on representative phosphonium diylides as an aid to interpreting the bonding in this class of compounds, where calcium and barium prefer to coordinate to a single iodide ion and several neutral oxygen donors rather than to the charged diylide.
Abstract: Treatment of potassium or lithium fluorenide with MePCl2 generates the organophosphine MeP(C13H9)2, which on reaction with methyl iodide produces the phosphonium species [Me2P(C13H9)2]I in 74% yield. In the solid state, H···I contacts of <3.3 A help generate a layered structure in which the fluorenyl rings are nearly parallel. On subsequent reaction of [Me2P(C13H9)2]I with either KH or K[N(SiMe3)2], the corresponding neutral phosphoylide, Me2P(C13H9)(C13H8), forms in 67% yield and was structurally characterized. The phosphonium iodide [Me2P(C13H9)2]I was allowed to react with Ae[N(SiMe3)2]2 (Ae = Ca, Ba), and the product from the reaction with the calcium complex was structurally identified as the salt [CaI(thf)5][Me2P(C13H8)2]. The anion, which is outside the coordination sphere of the calcium, represents the first structurally authenticated example of a free phosphonium diylide. The P−C(ylidic) bond length of 1.748(4) A reflects some partial multiple bond character. 1H and 31P NMR spectra suggest that t...