Ammonium Perrhenate Research Articles

Synthesis of cyclopentadienyltricarbonylrhenium(I) carboxylic acid from perrhenate

The cyclopentadienyltricarbonylrhenium(I) carboxylic acid 1, (η 5-C 5H 4COOH)Re(CO) 3, can be quickly prepared from ammonium perrhenate NH 4ReO 4. The synthetic pathway involves the use of mild conditions to reduce perrhenate to Re 2(CO) 10 followed by a thermal reaction of Re 2(CO) 10 with cyclopentadiene carboxylic acid in mesitylene. The yield from perrhenate is 35%. From pure Re 2(CO) 10, 1 can be obtained with a very good yield of 95%. This new and rapid synthetic pathway may be suitable for the preparation of radiopharmaceuticals.

Synthesis and Characterization of Rhenium Phosphinothiolate Complexes. Crystal and Molecular Structures of [HNEt3][Re{P(C6H4S)3}2], [ReOCl{OP(C6H5)2(C6H4S)}{(P(C6H5)2(C6H4S)}], [Re2O5{P(C6H5)2(C6H4S)}2], and [ReOCl{OP(C6H5)2(2-SC6H3-3-SiMe3)}2

The reactions of ammonium perrhenate, HCl(aq), and the phosphinothiol ligands (2-HSC6H4)P(C6H4X)2, where X = H or SH [abbreviated P−(SH)x (x = 1, 3)], in alcohol have led to the isolation of a series of rhenium complexes containing the {M(P−Sx)2} core, represented by [Re{P(C6H4S)3}{P(C6H4S)2(C6H4SH)}] (1), [ReOCl{OP(C6H5)2(C6H4S)}{P(C6H5)2(C6H4S)}] (3), and [ReOCl{OP(C6H5)2(2-SC6H3-3-SiMe3)}2] (5). The reaction of 1 with NEt3 results in the formation of [HNEt3][Re{P(C6H4S)3}2] (2) by deprotonation of a thiol ligand. The reaction of ammonium perrhenate with P−(SH) also led to the isolation of the binuclear species [ReOCl{OP(C6H5)2(2-SC6H3-3-SiMe3)}2] (4). Crystal data: 2, C43H42NP2S6Cl2Re, monoclinic, P21/c, a = 14.2484(2) A, b = 15.3108(1) A, c = 19.5121(2) A, β = 90.366(1)°, V = 4256.56(8) A3, Z = 2, 26 410 reflections, R = 0.0605; 3, C36H28O2P2S2ClRe,triclinic, P1, a = 9.3427(1) A, b = 11.9075(1) A, c = 16.8504(1) A, α = 98.177(1)°, β = 104.132(1)°, γ = 109.000(1)°, V = 1667.79(2) A3, Z = 2, 7567 refl...

Rhenium recovery from Sarcheshmeh molybdenite concentrate

Rhenium, in the form of ammonium perrhenate was recovered from Sarcheshmeh molybdenite concentrates by roasting the concentrates with slaked lime. The effect of the roasting parameters, such as roasting temperature, roasting materials and gas composition was investigated. The roasted materials were leached with water in order to separate the water-soluble calcium perrhenate and the water-insoluble compounds, calcium molybdate and calcium sulfate, that were formed during roasting. Impure rhenium-bearing solution was passed through a column of strong anionic quaternary resin (Dow IRA 410) for selective absorption of rhenium ions from the solution. Stripping of the column was carried out with hypochloric acid. The resultant perrhenic acid solution was exposed to hydrogen sulfide gas in order to precipitate rhenium heptasulfide. To produce ammonium perrhenate, the sulfide was decomposed by ammonia in the presence of hydrogen peroxide. The solution was evaporated and ammonium perrhenate crystals were formed.

On the formation of (CH 3) 4Re 2O 4 from methyl trioxorhenium complex CH 3ReO 3 under non-alkylating conditions

Attempts to deprotonate and alkylate at oxygen methyltrioxorhenium complex (MTO) by means of nitrogen ylides PhC(O)CH −N +R 1R 2R 3 led unexpectedly to the known dinuclear Re(VI) complex Me 4Re 2O 4 in 30% (R 1 = R 2 = R 3 = Et) and 72% (R 1 = Me, R 2R 3 = (CH 2) 5) yield, and to the corresponding ammonium perrhenates ReO 4 −PhC(O)CH 2N +R 1R 2R 3. Both complexes could be fully characterized by their spectroscopic data and by X-ray crystallography.

Synthesis and Structural Characterization of Mixed‐Ligand Oxorhenium(V) Complexes Containing Bidentate Dithioethers and Monothiolato Ligands

AbstractNeutral oxorhenium(V) complexes with dithioether ligands of the general formula [ReOX3(RS[CH2]2SR)], × = Cl, Br, R = nBu, Et, Bzl were synthesized. Ammonium perrhenate reacts in concentrated hydrochloric acid with dithiaalkanes (RS[CH2]2SR, R =nBu, Et, Bz) dissolved in glacial acetic acid to give octahedral complexes of the type [ReOCl3(RS[CH2]2SR)] (1a–c). In concentrated hydrobromic acid, nBu–S(Ch2)2S–nBu leads to the corresponding tribromo complexes (2). The X‐ray structure of shows a distorted octahedron with facial coordination of the bromide ligands. The sulfur atoms are cis coordinated to the terminal oxygen. Dissolution o f1a (R = nBu) in methanol leads to the substitution of the chloride trans to the oxo ligand by a meth oxy group. The resultant complex [ReOCl2(MeO) (nBu–S[CHL2]2S–nBu)] (3) is stable and can be isolated from methanolic solution, but changes to the μ‐oxo‐bridged dirhenium complex μ‐oxobis[dichloro(5,6‐dithiadidodecane)oxorhenium(V)] (4) when dissolved in other organic solvents. 1a reacts with an excess of benzenethiol by substitution of two chlorides to give the mixed‐ligand complex bis(benzenethiolate)chloro(5,8‐dithiadodecane)oxorhenium(V) (5a). The related 4‐methylbenzenethiolato complex 5b was synthesized starting from the μ‐oxo complex 4. X‐ray crystal structure determination of 5b shows the equatorial arrangement of the sulfur atoms. The trans position to the oxygen atom is occupied by a chloride ion.

ESR investigation of the phosphorous-rhenium center in γ-irradiated phosphate-doped ammonium perrhenate

Single crystals of ammonium perrhenate (NH 4ReO 4) doped with PO 3− 4 and γ-irradiated at RT (300 K) give rise to paramagnetic centers which could be recorded both at RT and 77 K. The radical has been identified as a pseudo V k center, namely a PO 2− 4 radical associated with ReO − 4. The g-tensor and the hyperfine A -tensor are found to be axially symmetric and are discussed in detail.

ESR investigation of the phosphorous-rhenium center in γ-irradiated phosphate-doped ammonium perrhenate

Single crystals of ammonium perrhenate (NH 4ReO 4) doped with PO 3− 4 and γ-irradiated at RT (300 K) give rise to paramagnetic centers which could be recorded both at RT and 77K. The radical has been identified as a pseudo V k center, namely a PO 2− 4 radical associated with ReO − 4. The g-tensor and the hyperfine A-tensor are found to be axially symmetric and are discussed in detail.

New rhenium centers in ammonium and potassium perrhenates

Single crystals of ammonium perrhenate (NH 4ReO 4) and potassium perrhenate (KReO 4) when γ-irradiated at 77 K gave new paramagnetic centers. The paramagnetic centers formed at 77 K are identified as ReO 3 and O − in both the samples. However, when temperature variation studies were carried out, it was found that these centers dissociate into ReO and O − 3 at about 230 K. The g-tensor and hyperfine ( A) tensor for all the centers observed in both the systems are found to be isotropic.

A computer simulation study of the disorder in ammonium perrhenate

Ammonium scheelites (of which ammonium perrhenate is an example) show several anomalies in their behaviour (including thermal contraction of the a lattice parameter, large thermal expansion of the c lattice parameter, enhanced nuclear quadrupolar relaxation, increased specific heat) which has been attributed to the onset of orientational disorder of the ammonium ions. Unlike in the ammonium halides there is no actual phase transition. Extensive molecular dynamics simulations of this material are reported. The model shows anomalies in the thermal expansion which are associated with a broadening and shift of the orientational distribution of the ammonium ions. There is no evidence of more than one preferred orientation. The ammonium ions also begin to jump between the twelve equivalent orientations, and we present evidence that this is primarily by rotation about one of the bonds. The activation energy for this agrees well with experiment. Angular and linear velocity-time correlation functions for the ammonium ion show rapid dephasing at higher temperatures, which is consistent with the observed broadening of the corresponding lines in the Raman spectrum. The origin of the anomalous thermal expansion is discussed in terms of various contributions to the entropy of the crystal.

Synthesis and Characterization of Nitrido(tetra‐tert‐butylphthalocyaninato)‐ rhenium(V) and Nitrido(phthalocyaninato)rhenium(V)

Abstract4‐tert‐Butylphthalodinitrile (1) reacts with ammonium perrhenate, NH4ReO4, to yield nitrido(tetra‐tert‐butylphthalocyaninato)rhenium(V), (tBu)4PcReN (2), which is characterized by IR, UV/Vis, CV, MS, 1H and 13C NMR, and elemental analysis. It shows good solubility in common organic solvents. In solution 2 is assumed to be monomeric whereas in the solid state also dimers or higher aggregates are present. From the NMR spectra it is concluded that different constitutional isomers of 2 are formed but not in the expected ratio of a statistical distribution. By analogy with 2, the already known nitrido(phthalocyaninato)rhenium(V), PcReN (3), is prepared for comparison.

Selective Recovery of Rhenium from Gas-Scrubbing Solutions of Molybdenite Roasting Using Direct Precipitation and Separation on Resins

Abstract Rhenium, a by-product of molybdenum's extractive metallurgy, can be recovered from acidic gas-scrubbing solutions by using the techniques of direct precipitation and separation on resin. Direct precipitation is achieved by using tetraphenylphosphonium bromide (φ4P). This technique yields an organometallic precipitate containing more than 25% Re and less than 1% Mo and Se. The reaction is fast and selective, with a stoichiometry φ4P/Re = 1/1. Separation on resins is achieved with a weak base anionic resin of the tertiary amine type. By using the reflux method, the weakly coadsorbed molybdenum and selenium are removed by a concentrated sulfuric acid solution containing rhenium. Rhenium is then selectively eluted by an ammoniacal solution from which pure ammonium perrhenate is crystallized.

Hydrogenation of oleic acid to 9‐octadecen‐1‐ol with rhenium‐tin catalyst

A new supported bimetallic catalyst, rhenium‐tin, is able to reduce oleic acid to 9‐octadecen‐1‐ol (cis andtrans isomers) with appreciable yield under mild hydrogenation conditions. This paper reports investigations on the effects of catalyst preparation methods, types of support, catalyst raw materials, mole ratio of the metals, activation and reaction conditions on the activity and selectivity of the catalyst. Catalyst derived from the combination of ammonium perrhenate and stannic chloride on alumina gave the best performance, and the presence of tin in the catalyst is essential for the preservation of the olefinic bond of the oleic acid during hydrogenation.

Thermal effects in the structure of ammonium perrhenate

The structure of ND 4 ReO 4 has been determined by neutron powder diffraction at 20 K intervals from 20 to 240 K and at 298 K. At 20 K the N-D bond distance is 1.025 (2) A, the Re-O bond distance is 1.733 (2) A and the D---O interionic distance is 1.878 (2) A. The thermal expansion is normal at low temperatures, but becomes anomalous above about 90 K. The anion orientation changes by 3.2 o over the whole temperature range while the cation orientation changes by 28 o , and at the higher temperatures the deuterium thermal ellipsoid becomes highly elongated in the direction perpendicular to the N-D bond

Metallcarbonyl‐Synthesen, XXI. Einfache Synthese eines präparativ nützlichen Alkoxy(carbonyl)metallats

Metal Carbonyl Syntheses, XXI. – Straightforward Synthesis of a Synthetically Useful Alkoxy(carbonyl)metallateAnionic methoxy complexes are formed upon carbonylation of ammonium perrhenate in methanol at 230–240°C. Thus, the dinuclear ionic complex [N(CH3)4][Re2(CO)6(μ‐OCH3)3] (2) results in 80% yield at CO pressures of ca. 100 bar, while the trinuclear derivative [N(CH3)4][Re3(CO)9(μ3‐OCH3)3(μ3‐OCH3)] (3) is due to lower pressure conditions (ca. 50 bar); 2 yields the bis(carbene) complex 4 of formula fac‐Re(CO)3L2I upon treatment with a bis(imidazolium) iodide, thus demonstrating that carbonylrhenium chemistry not necessarily depends on the availability of Re2(CO)10.

Thermochemistry of ammonium and rubidium perrhenates, and the effect of hydrogen bonding on the solubilities of ammonium salts

The standard enthalpies of formation of ammonium and rubidium perrhenate have been determined, and the difference between them, 132.8 ± 1.5 kJ mol–1 is, as previously predicted, consistent with the observed barrier to ammonium ion rotation of 9–10 kJ mol–1. New thermodynamic properties are proposed for the perrhenate ion, including Sm⊖(ReO4–, aq)= 198.1 ± 3 J K–1 mol–1, and derived values consistent with these are ΔfHm⊖(NH4ReO4, s)=–975 kJ mol–1, ΔfHm⊖(RbReO4, s)=–1 108 kJ mol–1, and Sm⊖(RbReO4, s)= 182 J K–1 mol–1. As with several other anions which provide relatively little resistance to ammonium ion rotation, the solubility of the ammonium salt exceeds that of the rubidium compound. This may be attributable to hydrogen bonding of the ammonium ion in aqueous solution.

Raman spectroscopic studies of the effects of tin promotion on a rhenium/alumina dismutation catalyst

Raman spectroscopic studies have been carried out on a rhenium/alumina catalyst, active in metathesis reactions. Raman data comparing the state of the rhenium on the fresh catlyst (freshly activated and following air exposure), and on catalyst promoted with tetramethyltin are presented.The ammonium perrhenate impregnated alumina catalyst precursor contains a tetrahedral oxidic rhenium species in a hydrated state. When the precursor is activated, a reduction in the number of attached hydroxyl groups and a distortion of the tetrahedral rhenium moiety occurs. The extent of hydration of the rhenium phase is therefore an important parameter determining metathesis activity. There is no evidence for the presence of a surface rhenium heptoxide phase.An extra Raman band at 777 cm–1, observed following tetramethyltin promotion, is attributed to a Re–Sn vibration. This Re–Sn interaction may be responsible for the observed promotional effect.

ChemInform Abstract: Reduction of Ammonium Pertechnetate and Ammonium Perrhenate with CO: Synthesis of M2(CO)10 (M: Tc, Re) and Crystal and Molecular Structure of the Trinuclear Cyano‐Bridged Derivative Re3(CN)3(CO)12.

AbstractThe decacarbonyl (III) and (VI) are obtained by CO reduction of (I) and (V), respectively, under high pressure and high temperature.

Atomic absorption determination of traces of elements in ammonium perrhenate of high purity

Methods for the determination of traces of As, Bi, Ca, Cd, Co, Cu, Cr, Fe, In, K, Mg, Mn, Mo, Na, Ni, Pb, Se, Si, Sb, Sn, Te, Tl, V and Zn in ammonium perrhenate of 99.99% –99.999% purity grade are proposed. Na, K, Ca, Mg and Si are determined directly in the aqueous sample solution, while the remaining elements, except Mo, are determined after preliminary extractive separation of their dithiocarbamate complexes at two different pH-values (8-9 and 5–6). Mo is separated from the matrix by extraction with α-benzoinoxime. The analaysis is carried out by FAAS or ETAAS, depending on the concentration of the corresponding trace elements. The recovery factor is checked for impurity amounts of 1 μg/ml and 0.2 μg/ml, respectively.

EXAFS-XANES studies of Re oxide-alumina and Cr oxide-silica catalysts

Extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) spectra were obtained for chromium(VI) oxide species on silica, ammonium perrhenate on alumina and for their various products after calcination in dry air. After impregnation, the Cr oxide species at low loading correspond to Cr-O tetrahedra occurring as near-neighbour clusters on the surface, while at high loading a Cr 2O 7-like molecular structure is retained within gross clumps of Cr-containing material; after calcination at 525°C, significant clusters of Cr oxides remain at the surface. For ammonium perrhenate on alumina, ReO 4 tetrahedra prevail at high loading in structures resembling crystalline NH 4ReO 4, while at 2.5% Re loading the supported Re adopts a cluster structure close to that of Re 2O 7, perhaps as a thin layer, even after low temperature drying. After calcination, the higher Re-loading materials still retain a perrhenate-like structure and do not suffer simple decomposition to produce rhenium(VII) oxide.

Novel rhenium catalysts (chlorides and/or alkoxides dispersed on inorganic supports) for metathesis: A comparison with ammonium perrhenate precursors

The trans-/cis- ratios in 9-octadecene, 2, monoester, 1, and dimethyl 9-octadecenedioate, 3, produced in the metathesis of methyl oleate, cis-1, are measured against time for a series of rhenium-supported precursors (ReO x /γ-alumina or ReO x /silica-alumina 25% SiO 2 and 75% SiO 2). These trans-/cis- ratios show a marked dependence on the nature of the support. An explanation is proposed in terms of specific support interactions. The effect of the precursors is also considered. Easily accessible inorganic chloro complexes such as potassium hexachlororhenate(IV), K 2ReCl 6], and/or lsrhenium pentachloriders (see text), Re 2Cl 10, are used to prepare bifunctional heterogeneous catalysts which catalyze both double bond isomerization and metathesis of 1-octene at room temperature. Activation of the catalysts can be achieved by thermal treatments in nitrogen, the final temperature being in the range 300–360°C. Several chemical species of rhenium are evidenced by XPS analysis for the active catalysts. It should be emphasized that the XPS spectral differences between the catalysts prepared with K 2[ReCl 6] and those obtained with Re 2Cl 10 on silica-alumina (75% SiO 2) are correlated with the different catalytic reactivities. These novel rhenium catalysts can be modified to generate ‘tailor-made catalysts’.