Tetrahydrofuran Complex Research Articles

Synthese und Charakterisierung neuer Acetylenkomplexe des Mangans und Rheniums

The reaction of the photochemically-generated tetrahydrofuran complexes Cp′(CO) 2M(thf) (Cp′  η 5-C 5H 5, η 5-C 5H 4Me, η 5-C 5Me 5; M  Mn, Re) with various alkynes R 1C 2R 2 (R 1, R 2  H, Me, Ph) yields are acetylene complexes Cp′(CO) 2MR 1C 2R 2. These compounds were identified from their IR, 1H NMR, 13C NMR and mas spectra.

Interaction site enthalpies of the phenol–tetrahydrofuran hydrogen-bond complex in various solvents

Enthalpies of solution of several solutes in cyclohexane, benzene, toluene, p-xylene, carbon tetrachloride and 1,1,2,2-tetrachloroethane have been measured. They permitted a determination of the interaction site enthalpies of phenol (Ph) and tetrahydrofuran (THF) molecules with the solvents mentioned above. Spencer's additive model of solute–solvent interaction was used. These interaction site enthalpies were used to calculate the enthalpies of PH–THF complex formation [ΔH(complex)] and transfer enthalpies [ΔHtr(complex)] of this complex from cyclohexane to other solvents used. A good agreement between the calculated and experimental values of ΔH(complex) and ΔHtr(complex) shows the correctness of the simple model of molecular interactions being used.

Preparation and crystal structures of tetrakis(methyltrihydroborato)uranium(IV)bis(tetrahydrofuranate) and tetrakis(methyltrihydroborato)uranium(IV)tetrahydrothiophenate

The U(IV) complexes, U(BH 3CH 3)·20C 4H 8 and [U(BH 3CH 3) 4·SC 4H 8] 2, have been prepared and their structures determined. Crystals of (BH 3CH 3) 4U·20C 4H 8 are orthorhombic, Aba2, with a=12.911(3), b=16.072(4), c=10.116(4) Å, at 23 °C. For Z=2 the calculated density is 1.574 g/cm 3. Crystals of [(CH 3BH 3) 4U·SC 4H 8] 2 are monoclinic, P2 1/ c, with a=12.054(2), b=16.372(3), c= 18.545(3) Å and β=108.82(2)° at 23 °C. For Z=4 the calculated density is 1.694 g/cm 3. The structures were refined by full-matrix least-squares to a conventional R factor of 0.028, [1378 data, F 2>;2σ( F 2)] for the tetrahydrofuran complex, and 0.038 [2732 data, F 2>;2σ F 2] for the tetrahydrothiophen plex. The tetrahydrofuran complex is monomolecular with the uranium atom on a two-fold axis and coordinated to four methyltrihydroborato and two tetrahydrofuran ligands; the UB distances are 2.55(2)and 2.58(2) Å, and the UO distance is 2.485(6) Å. The tetrahydrothiophene complex is a dimer in which two sulfur atoms bridge the uranium atoms of two tetra(methyltrihydroborato)uranium(IV) molecules; the UB distances range from 2.468(2) to 2.591(2) Å, and the US distances are 3.120(4) and 3.239(5) Å; the SS and UU distances in the bridge are 3.477(5) and 5.374(1) Å, respectively.

Main group-conjugated organic anion chemistry. 1. Synthesis of magnesium anthracene, silylated anthracenes, or fluoranthene tetrahydrofuran and tertiary amine complexes and of magnesium cyclooctatetraene: x-ray structure of [MgL(TMEDA)].cntdot.[MgL(THF)2] (L = 9,10-bis(trimethylsilyl)anthracene)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMain group-conjugated organic anion chemistry. 1. Synthesis of magnesium anthracene, silylated anthracenes, or fluoranthene tetrahydrofuran and tertiary amine complexes and of magnesium cyclooctatetraene: x-ray structure of [MgL(TMEDA)].cntdot.[MgL(THF)2] (L = 9,10-bis(trimethylsilyl)anthracene)Teresa. Alonso, Stephen. Harvey, Peter C. Junk, Colin L. Raston, Brian. Skelton, and Allan H. WhiteCite this: Organometallics 1987, 6, 10, 2110–2116Publication Date (Print):October 1, 1987Publication History Published online1 May 2002Published inissue 1 October 1987https://doi.org/10.1021/om00153a014RIGHTS & PERMISSIONSArticle Views866Altmetric-Citations37LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (938 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

ChemInform Abstract: Selective Reduction of the Formylated Bile Acids to the Corresponding Formylated Bile Alcohols Analogs.

AbstractThe derivatives (I) of cholic acid or bile acid are converted to the corresponding steroid alcohols (II) by selective reduction with borane/ tetrahydrofuran complex.

Alkylidynephosphines : syntheses and reactivity

In the past, different methods have been utilized for the preparation of alkylidynephosphines. Whereas, however, small amounts of thermally instable derivatives might be obtained from reactions in the gas phase, the synthesis of phosphines which are stable under an inert atmosphere, as for instance those with a tert-butyl or a 1-adamantyl substituent at the carbon atom of the PEC group, is best started with tris (trimethylsilyl) phosphine itself or with the more reactive lithium bis (trimethylsilyl) phosphide.2 tetrahydrofuran complex. Treatment of either compound with acyl halides results in the formation of acylbis (trimethylsilyl) phosphines which, at room temperature, rearrange to the corresponding trimethylsilyl [1-(trimethylsiloxy) alkylidene] isomers. As traces of hydrogen halide accelerate the conversion of tris (trimethylsilyl) phosphine to the triacyl derivatives, the use of the lithium phosphide is strongly recommended in all cases where impure acyl halides are used. In the presence of small amounts of solid sodium hydroxide suspended in an etherial solvent, the thus prepared trimethyl[1-(trimethylsiloxy)-alkylidene]phosphines eliminate hexamethyldisiloxane to yield the required alkylidyne compounds. Running the decomposition without a solvent at a higher temperature, Regitz and coworkers were able to improve this method further.

Spectrophotometric Determination of Iron(III) as Azide Complexes in Aqueous Tetrahydrofuran

Abstract A simple, sensitive and alternative method for the spectrophotometric determination of iron(III) has been established. The procedure is based on the formation of iron-azide complexes in 60% (v/v) tetrahydrofuran/ water medium. The high sensitivity obtained in this method is due to the use of an interesting absorption band not previously reported in the literature. In the recommended conditions, absorbances for the ferric complexes are measured at 400 nm where the molar absorptivity is 1.52 × 104 1 mol−1 cm−1. The organic solvent used increases the sensitivity and the stability of the measurements. The precision is shown by the average deviation of about 0.3%. This system obeys Beer's law and is suitable for iron(III) determination in the concentration range from 0.6 to 3.2 mg 1−1 (ppm). The best experimental conditions were determined studying the different factors involved. The influence of various diverse ions was also studied.

Acidities of arenetricarbonylchromium(0) complexes in tetrahydrofuran

The measurement of acidities of arenetricarbonylchromium(0) complexes in tetrahydrofuran reveals the acid-strengthening effect of complexation to be 6–7 p K units and the p K of benzene to be 41.

Unusually Coordinated Phosphorus Compounds; 71. Adamant-1-ylmethylidynephosphine, A New, Stable Phosphaalkyne

The reaction of tris[trimethylsilyl]phosphine (4a) as well as of the lithium bis[trimethylsilyl]phosphide·; tetrahydrofuran complex (4b) with 1-adamantoyl chloride (5) results in the formation of the phosphaalkene 7 in 67% or 96% yield, respectively. Subsequent sodium hydroxide or tetra-n-butylammonium fluoride-catalysed elimination of hexamethyldisiloxane from 7 at 20/90 °C gives rise to the phosphaalkyne 8 in 83 or 71% yield. The phosphaalkyne 8 undergoes smooth [3 + 2]cycloaddition reactions with 1,3-dipoles such as the nitrile oxide 9, the diazo compounds 12a-c, and the azide 15 to produce the phospholes 11,14a-c, and 16, respectively. The phosphaalkene 7 reacts with the dipoles 9 and 12a to give the same cycloadducts 11 and 14a, respectively. In these two reactions, the primary adducts undergo spontaneous (10 → 11) or sodium hydroxide-catalysed (13 → 14a) elimination of hexamethyldisiloxane.

Preparation of urea-poly(tetrahydrofuran) complexes and their application for fractionation of oligomers

The synthesis of the urea channel inclusion complexes of poly(tetrahydrofuran)) (PTHF) is described. These complexes could be obtained in the form of single crystals forM n ≤ 1700 g/mol of PTHF as the guest, and they exhibit a hexagonal unit cell (a=8.20(2) A,c=11.05(3) A) very similar to the wellknown urea-n-alkane complexes. X-ray investigations, elemental analysis and density measurements suggest an all trans zig-zag conformation of the polymer chain. The formation of the complexes was exploited for the purpose of fractionation of PTHF, making use of the correlation between temperature of crystallization andM n of the included polyether chain. The distribution and the molecular weights of the fractions, obtained by extractive crystallization, were determined by reversed phase HPLC analysis and vapour pressure osmometry (VPO). Narrow fractions with Mw/Mn=1.02 were obtained from commercial PTHF samples. Successive fractionation was applied also on product mixtures from oligomer synthesis, as demonstrated for the separation of the dodecamer H-(o-(CH2)4-)12OH.

Organoboron compounds: CDVII. Reaction of 1-boraadamantane with phosphorus ylides: synthesis of 4-alkyl-3-borahomoadamantanes

Alkylidenetriphenylphosphoranes react with the tetrahydrofuran complex of 1-boraadamantane to form stable adducts. The adducts rearrange to compounds of the 4-alkyl-3-borahomoadamantane series.

Resonance Raman studies of carbon monoxide binding to iron "picket fence" porphyrin with unhindered and hindered axial bases. An inverse relationship between binding affinity and the strength of iron-carbon bond.

The stretching frequency of the iron-carbon bond, v(Fe-CO), is a direct measure of the iron-carbon bond strength when there is no change in the Fe-C-O geometry. Here we report resonance Raman detection of v(Fe-CO) frequencies in the CO complexes of iron (II) alpha, alpha, alpha, alpha-mesotetrakis(o-pivalamidophenyl)porphyrin, FeII(TpivPP), with trans ligands of varying strength: N-methylimidazole (N-MeIm), 1,2-dimethylimidazole (1,2-Me2Im), pyridine (py), and tetrahydrofuran (THF). It was found that the weaker the iron-trans ligand bond, the stronger the iron-carbon bond. Comparisons of sterically hindered (1,2-Me2Im) and unhindered (N-MeIm) bases are of particular interest because of their implication in the phenomenon of hemoglobin cooperativity and the mechanisms of protein control of heme reactivity. While the CO binding affinity of FeII(TpivPP)(1,2-MeIm) is approximately 400 times lower than that of FeII(TpivPP)(N-MeIm), the v(Fe-CO) frequency for the former (at 496 cm-1) is higher than that for the latter (at 489 cm-1). This example shows that the CO binding affinity cannot be directly correlated with the strength of the iron-carbon bond. Comparison of the CO binding to FeII(TpivPP)(THF) and FeII(TpivPP)(N-MeIm) reveals a similar relationship; the v(Fe-CO) frequency (at 527 cm-1) in FeII(TpivPP)(THF)(CO) is 38 cm-1 higher than that in FeII(TpivPP)(N-MeIm)(CO), but the CO binding affinity is lower for the THF complex.

Kinetics and thermodynamics of dissociation of nickel(II)–isoquinoline complexes in tetrahydrofuran. Effect of trace water on ligand substitution kinetics

Rate constants and associated activation parameters for the dissociation of (solv)5Ni(isoquin)2+(solv = solvent, isoquin = isoquinoline) were determined in tetrahydrofuran (THF) over the range 15 to 35 °C by stopped-flow spectrophotometry. Comparison of the enthalpy of activation [Formula: see text] for the dissociation of (solv)5Ni(isoquin)2+ in THF with previous results in other solvents reveals that the linear relation between [Formula: see text] for the dissociation of this ion in the various solvents and the Gutmann donicity can be extended to THF. From this relation the donor number of THF is found to be 18.8 ± 0.5, in agreement with the value 19.3 reported from other methods. Dissociation of (solv)5Ni(isoquin)2+ in THF is controlled by an Id-type mechanism, as was previously observed in other protic and aprotic solvents. The rate of dissociation in THF is strongly affected by the free-water concentration in the medium.

Synthesis and properties of tetrahydrofuran complexes of chromium(III). [Cr(THF)3X3] (X = Cl, Br, I), [Cr(THF)2X4]- (X = Cl, Br, I, NCS), and "[Cr(THF)6](BF4)3"

Synthesis and properties of tetrahydrofuran complexes of chromium(III). [Cr(THF)3X3] (X = Cl, Br, I), [Cr(THF)2X4]- (X = Cl, Br, I, NCS), and "[Cr(THF)6](BF4)3"

Infrared and Raman spectroscopy of uranyl (hexafluoroacetylacetonate) 2 adducts in the vapor and condensed phases

The vapor phase mid-infrared spectra and solution phase far-infrared and Raman spectra have been measured for a series of volatile uranyl (hexafluoroacetylacetonate) 2 adducts. Using 18O-isotopic labelling and correlations with spectra of adducts possessing trifluoroacetylacetonate and acetylacetonate ligands, a more complete set of assignments has been made, especially for the low-frequency metal-ligand vibrations. The tetrahydrofuran (THF) complex is unusual in that the UO 2 symmetric stretch possesses anomalously high infrared intensity, which is ascribed to perturbation of the UO 2 moiety by steric interactions with the α-CH 2 group of the adduct.

Polymer‐supported dinitrogen complexes of manganese. Coordination of molecular nitrogen in solid‐gas phase reaction under mild conditions

AbstractA copolymer (PC‐1) was synthesized from a mixture of 1,2‐and 1,3‐isomers of tricarbonyl‐(methylvinylcyclopentadienyl)manganese (1) and styrene (St) crosslinked with 1,4‐divinylbenzene, and a membrane (PM–1) consisting of the 1/St copolymer. A polymer‐supported dinitrogen complex (PC‐4) was prepared from the tetrahydrofuran (THF) complex of PC‐1 and molecular nitrogen in a solid‐gas phase reaction under moderate conditions. The dinitrogen complex membrane (PM–4) was readily obtained directly from PM‐1 by a “one‐step reaction” on UV light irradiation under normal pressure of nitrogen at room temperature. A prominent feature of polymer‐supported dinitrogen complexes, PC‐4 and PM‐4, is their high stability as compared with the corresponding low molecular weight analogues. The coordinated nitrogen can be substituted by carbon monoxide in a PC‐4/THF mixture. The mechanism of nitrogen co‐ordination to PC‐1 and PM‐1 was investigated by means of IR and/or absorption spectrometry.

Photochemical behavior of a uranyl bis(hexafluoroacetylacetonate)-tetrahydrofuran complex. 1

Electronic excitation of solutions of the THF adduct of uranyl hexafluoroacetylacetonate results in production of a U/sup 4 +/ product. Spectral and wet-chemical analyses suggest it is U((CF/sub 3/CO)/sub 2/CH)/sub 4/. It is proposed that it occurs through the intermediacy of a hypothetical U/sup 4 +/-peroxide complex, an isomer of UO/sub 2//sup 2 +/. The excited uranyl interacts with oxygen which acts as a fluorescence quenching agent.

ChemInform Abstract: HARD LIGANDS AS DONORS TO SOFT METALS. PART 3. CATIONIC BIS(SOLVENT) COMPLEXES OF PALLADIUM(II); CATIONS FOR CATALYSIS

AbstractBehandelt man den Dichlorokomplex (I) mit 2 Äquivalenten eines Silbersalzes in Gegenwart eines schwachen Lösungsmittelliganden, so bilden sich die kationischen Komplexe (II).

Hydride transfer reactions in the series of 1-boraadamantane “ate”-complexes

Lithium 1-alkyl-1-boraadamantanates, obtained from lithium alkyls and the tetrahydrofuran complex of 1-boraadamantane, afford 7-methylene-3-alkyl-3-borabicyclo[3.3.1]nonanes when treated with acetyl chloride. With the use of selectively deuterated lithium [7-D]-1,3,5-trimethyl-1-boraadamantanate, it is shown that the reaction involves the elimination of deuteride ion from the β-carbon atom.

Synthesis and structure of Co[Tl(SCN) 2] 2 and its derivatives

The binuclear mixed-metal tetrathiocyanate complex Co[Tl(SCN) 2] 2 was synthesized and was reacted with certain Lewis bases. It was observed that the Lewis bases (solvents) with a dielectric constant less than 24.3 and a donor number less than 17 do not have any effect on the Lewis acid, that those with a donor number in the range 17–30 form polymeric bridged complexes and that those with a donor number above 30 and a dielectric constant below 36 form cationic-anionic complexes. The complexes were characterized by elemental analysis, conductance measurements, magnetic susceptibility measurements and IR and electronic spectral studies. These investigations indicate that the tetrahydrofuran, dimethylformamide, dimethylsulphoxide, methanol, ethanol and acetone complexes are polymeric bridged complexes, that the triphenylphosphine complex is monomeric and that the pyridine, aniline, nicotinamide, 2,2′-bipyridyl and 1,10-phenanthroline complexes are cationic-anionic. Quantitative softness values E ° n and E ° m indicate that all the ligands prefer to coordinate with cobalt rather than with thallium.