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The β- emitter, rhenium-188 (188Re), has long been recognized as an attractive candidate for targeted cancer radionuclide therapy (TRNT). This transition metal shares chemical similarities with its congener element technetium, whose nuclear isomer technetium-99m (99mTc) is the current workhorse of diagnostic nuclear medicine. The differences between these two elements have a significant impact on the radiolabelling methods and should always receive critical attention. This review aims to highlight what needs to be considered to design a successful radiopharmaceutical incorporating 118Re. Some of the most effective strategies for preparing therapeutic radiopharmaceuticals with 188Re are illustrated and rationalized using the concept of the inorganic functional group (core) and a simple ligand field theoretical model combined with a qualitative definition of frontiers orbitals. Of special interest are the Re(V) oxo and Re(V) nitrido functional groups. Suitable ligands for binding to these cores are discussed, successful clinical applications are summarized, and a prediction of viable future applications is presented. Rhenium-188 decays through the emission of a high energy beta particle (2.12 MeV max energy) and a half-life of 16.9 h. An ideal biological target would therefore be a high-capacity target site (transporters, potential gradients, tumour microenvironment) with less emphasis on saturable targets such as overexpressed receptors on smaller metastases. ispartof: MOLECULES vol:28 issue:3 ispartof: location:Switzerland status: published

Cationic metal-organic framework (MOF) materials are widely used in the anion separation field, but there are few reports of pyrimidyl ligands as building units. In this work, three new cationic MOFs based on pyrimidyl as functional group ligands were synthesized for the removal of radioactive pertechnetate from aqueous solution. The pyrimidyl ligands were designed by incorporating pyrimidyl units into the skeletons of benzene, triphenylamine, and tetraphenylethylene, respectively. Taking advantage of multiple coordination sites of pyrimidyl groups, three cationic MOFs (ZJU-X11, ZJU-X12, and ZJU-X13) with diverse structures were solvothermally synthesized using silver ion as the metal node. Scanning electron microscopy-energy-dispersive spectroscopy mapping demonstrated that these three cationic MOFs could capture ReO4- via anion exchange, but the sorption capabilities were distinctly different. With 95% removal toward ReO4-, ZJU-X11 showed the strongest anion-exchange competence among the three MOFs. According to the results of batch experiments, ZJU-X11 could achieve sorption equilibrium within 10 min, remove 518 mg of ReO4- per 1 g of ZJU-X11, remove most of ReO4- after four recycles, and maintain satisfactory selectivity in the presence of excess competing anions, which is one of the best MOF materials for removing ReO4-/TcO4- among the three cationic MOFs. This work indicates that the pyrimidyl group is a promising multiple site to build versatile cationic MOFs.

In this communication experimental and theoretical results are reported affording strong evidence that interactions between electron rich atoms and the metal of tetroxide anions of group 7 elements are a new case of attractive and σ-hole interactions. Single crystal X-ray analyses, molecular electrostatic potentials, quantum theory of atoms-in-molecules, and noncovalent interaction plot analyses show that in crystalline permanganate and perrhenate salts the metal in Mn/ReO4- anion can act as electron acceptors, the oxygen of another Mn/ReO4- anion can act as the donor and supramolecular anionic dimers or polymers are formed. The name matere bond (MaB) is proposed to categorize these noncovalent interactions and to differentiate them from the classical metal-ligand coordination bond.

The effective removal of radioactive 99TcO4- anion from nuclear wastewater remains a very difficult unsolved problem. Functional adsorbent materials with high stability, anion-exchange capacity, excellent selectivity, and recyclability are much needed to solve this problem. In this work, we designed two stable cationic metal-organic frameworks (MOFs)-Zr-tcbp-Me and Zr-tcpp-Me-for possible use as adsorbent materials to remove 99TcO4-. Both compounds were synthesized by solvothermal reactions of the tetracarboxylate ligand with zirconium salt, followed by postsynthetic modification (N-methylation). The crystallinity of both zirconium-based MOFs can be well retained under harsh conditions, and they exhibit high adsorption capacity and selectivity toward ReO4- anion, a nonradioactive analogue of 99TcO4-. Zr-tcbp-Me and Zr-tcpp-Me demonstrate the highest framework stability toward acidity among all previously reported cationic MOFs that have been tested for perrhenate removal from wastewater.

99Tc is one of the most abundant radiotoxic isotopes in used nuclear fuel with a high fission yield and a long half-life. Effective removal of pertechnetate (TcO4-) from an aqueous solution is important for nuclear waste separation and remediation. Herein, we report a series of facilely obtained benzene-linked guanidiniums that could precipitate TcO4- and its nonradioactive surrogate ReO4- from a high-concentration acidic solution through self-assembly crystallization. The resulting perrhenate and pertechnetate solids exhibit exceptionally low aqueous solubility. The benzene-linked guanidiniums hold one of the highest TcO4- removal capacities (1279 mg g-1) among previously reported materials and possess a removal percentage of 59% for ReO4- in the presence of Cl- over 50 times. The crystallization mechanism was clearly illustrated by the single-crystal structures and density functional theory calculations, indicating that TcO4- is captured through a charge-assisted hydrogen bonding interaction and stabilized by π-π stacking layers. In addition, the removal process is easily recycled and no toxic organic reagents are introduced. This work provides a green approach to preliminarily separate TcO4- from high-level nuclear wastes.

Re2O7 in hexafluoroisopropyl alcohol provides access to cationic intermediates from alcohols through the intermediacy of perrhenate esters. This manuscript describes the application of the system to the formation of a number of weakly basic heterocyclic systems through dehydration reactions and intramolecular nucleophilic addition. The influence of the substrate structure on the reaction rates and stereocontrol is discussed with respect to intermediate ion pairs.

The strength of hydrogen bonding to and structure of hydrated oxometallate ions in aqueous solution have been studied by double difference infrared (DDIR) spectroscopy and large-angle X-ray scattering (LAXS), respectively. Anions are hydrated by accepting hydrogen bonds from the hydrating water molecules. The oxygen atom of the permanganate and perrhenate ions form weaker and longer hydrogen bonds to water than the hydrogen bonds in bulk water (i.e., they act as structure breakers), while the oxygen atoms of the chromate, dichromate, molybdate, tungstate, and hydrogenvanadate ions form hydrogen bonds stronger than those in bulk water (i.e., they act as structure makers). The oxometallate ions form one hydration shell distinguishable from bulk water as determined by DDIR spectroscopy and LAXS. The hydration of oxoanions results in X–O bond distances ca. 0.02 Å longer than those in unsolvated ions in the solid state not involved in strong bonding to counterions. The oxygens of oxoanions with a central atom from the second and third series in the periodic table and the hydrogenvanadate ion hydrogen bind three hydrating water molecules, while oxygens of oxoanions with a heavier central atom only form hydrogen bonds to two water molecules., The strength of the hydrogen bonding to and the structure of hydrated oxometallate ions in aqueous solution have been studied by double difference infrared spectroscopy and large-angle X-ray scattering, respectively.

New coordination compounds of iron(II) sulfate, hexafluorosilicate, and perrhenate with 2,6-bis(benzimidazole-2-yl)pyridine (L), namely, [FeL2]SO4 ∙ H2O (I), [FeL2]SiF6 ∙ H2O (II), and [FeL2](ReO4)2 ∙ 1.5H2O (III) have been synthesized. The complexes have been studied by static magnetic susceptibility, electronic (diffuse reflectance), IR, and Mossbauer spectroscopy, and X-ray diffraction. The μeff(T) study of dehydrated complexes I–III (1–3) within the range 80–520 K has shown the spin transition 1А1 ⇔ 5Т2. A two-stage transition is observed in complex 1, whereas one-stage transitions occur in complexes 2 and 3. The forward spin transition temperatures (Тс↑) of complexes 1–3 are 423 and 503, 476, 362 K, respectively. Complex 3 sustains an abrupt spin transition with a hysteresis in the μeff(T) curve (ΔT = 21 K).

The anions pertechnetate, TcO4-, and perrhenate, ReO4-, exhibit very similar chemical and physical properties. Revealing and understanding disparities between them enhances fundamental understanding of both. Electrospray ionization generated the gas-phase proton bound dimer (TcO4-)(H+)(ReO4-). Collision induced dissociation of the dimer yielded predominantly HTcO4 and ReO4-, which according to Cooks' kinetic method indicates that the proton affinity (PA) of TcO4- is greater than that of ReO4-. Density functional theory computations agree with the experimental observation, providing PA[TcO4-] = 300.1 kcal mol-1 and PA[ReO4-] = 297.2 kcal mol-1. Attempts to rationalize these relative PAs based on elementary molecular parameters such as atomic charges indicate that the entirety of bond formation and concomitant bond disruption needs to be considered to understand the energies associated with such protonation processes. Although in both the gas and solution phases, TcO4- is a stronger base than ReO4-, it is noted that the significance of even such qualitative accordance is tempered by the very different natures of the underlying phenomena.

The structures and dynamics of quinuclidinium perrhenate, which is the first example of a plastic/ferroelectric crystal, were investigated by molecular dynamics simulation. Our simulation results s...

Counterions have a significant effect on the efficiency of the deoxydehydration (DODH) reaction. Four perrhenate salts, Z+ReO4− (Z = Na+, K+, NH4+, and Bu4N+), were tested in the DODH reaction of a vicinal diol in the presence of PPh3 as the reductant. In addition, a new perrhenate salt, (2-ppyH)[ReO4] (2-ppyH+ = 2-phenylpyridinium cation), has been synthesized and characterized by X-ray crystallography and utilized as an efficient catalyst in the DODH reaction. Since so far computational studies related to the influence of the counterion in the different steps of the DODH mechanism are scarce, we have carried out a comparative investigation of the counterion effect using density functional theory (DFT) calculations. The DODH mechanism of the conversion of phenyl-1,2-ethanediol to styrene in the presence of the five perrhenate salts mentioned above, as well as bare perrhenate (ReO4−) was studied from an energetic point of view. The catalytic tests and concomitant DFT computations confirmed the general mechanistic aspect in which the counterion plays an active role in all stages of the reaction mechanism including intermediate structures, Gibbs free energy changes (ΔG°g and ΔG°sol), transition states, and activation barrier energies. The role of counterion type has been considered in three key steps of the reaction mechanism, including the proton-transfer from diol to oxo-ligand in the rhenium moiety, the nucleophilic attack of the P atom from PPh3 on the oxo-ligand, the dissociation of the OPPh3 ligand, and the olefin extrusion from the Re(V)-diolate intermediate for each perrhenate salt. The crucial roles played by the counterion in terms of structure arrangement during transition states and the activation energy barriers are finally discussed.

The standard (p° = 0.1 MPa) molar enthalpies of sublimation, at 298.15 K, of methyltrioxorhenium(VII), Δ sub H m o [CH3ReO3] = 70.2 ± 0.4 kJ mol−1, and dirhenium decacarbonyl, Δ sub H m o [Re2(CO)10] = 97.4 ± 0.9 kJ mol−1, corresponding to well characterized crystalline phases, were determined by Calvet microcalorimetry. These results, along with structural information obtained in this work by single crystal X-ray diffraction for CH3ReO3, or previously reported for Re2(CO)10, tetramethylammonium perrhenate(VII), [N1111][ReO4], and hexamethylrhenium(VI), Re(CH3)6, were used to extend our previously developed all-atom force field for organometallic compounds, to rhenium species. The new parametrization was able to reproduce the enthalpies of sublimation and unit cell parameters of the test set with maximum absolute deviations of 3.3 kJ⋅mol−1 and

Heat capacity for 1-hexyl-3-methyl imidazolium perrhenate ionic liquid [C6MIM][ReO4] in the temperature range from 79 to 396 K has been measured by a fully automated adiabatic calorimeter. For [C6MIM][ReO4], glass transition temperature, the melting temperature, standard molar heat capacity, enthalpy and entropy of solid–liquid phase transition were determined to be (202.164 ± 0.405) K, (226.198 ± 0.265) K, (480.702 ± 0.013) J K−1 mol−1, (15.665 ± 0.195) kJ mol−1 and (69.250 ± 0.780) J K−1 mol−1, respectively. In addition, the thermodynamic characteristics and solid–liquid phase change behavior of [C6MIM][ReO4] were compared with the ones of [C7MIM][ReO4] reported in the literature. The thermodynamic functions (HT− H298.15), (ST− S298.15) and (GT− G298.15), for the compound in the experimental temperature range were calculated.

The ionic liquid 1-(2-methoxyethyl)-3-ethyl imidazolium perrhenate [C22O1IM][ReO4] was prepared in the laboratory firstly, and its structure was confirmed by 1H NMR and 13C NMR. The heat capacities were precisely measured in the temperature range from 78 to 392 K by means of a fully automated adiabatic calorimeter. For [C22O1IM][ReO4], the melting temperature, standard molar heat capacity, molar enthalpy, and molar entropy of solid–liquid phase transition were determined to be (211.826 ± 0.130) K, (142.31 ± 0.34) J K−1 mol−1, (14.382 ± 0.046) kJ mol−1, and (67.93 ± 0.22) J K−1 mol−1, respectively. And the experimental values of molar heat capacities were fitted to a polynomial equation using least square method in the appropriate temperature ranges. The thermodynamic functions (HT − H298.15) and (ST − S298.15) were also obtained from the heat capacity data in the experimental temperature range with an interval of 5 K.

Rhenium and molybdenum are valuable metals present in the earth's crust in very low concentration and are increasingly used in industry thanks to their multiple properties, but due to the harmful aspects of the production process, there is a need to develop systems of concentration or purification of salts of these elements. For this work a PEG/Na2MoO4 aqueous two phase system (ATPS) was used for the partition of ReO4- anion. By using a central composite design, the effects of PEG concentration, sodium molybdate concentration, temperature, pH and their possible interaction on the partition coefficient were studied, also to estimate the optimal configuration of the factors that influence the process. At the same time, experimental density, sound velocity and isentropic compressibility were also obtained for top and bottom phases. The results showed that the optimal conditions for the partition of ReO4− anion using the ATPS formed by PEG and Na2MoO4 were 14.7 wt% PEG 4000, 16.3 wt% Na2MoO4, 35 °C and pH 6. For these conditions, the partition coefficient (K) obtained was up to 17.8 ± 0.78. The order of factors with high significance on the partition coefficient was: Na2MoO4 concentration > PEG concentration > temperature > pH > interaction between Na2MoO4 and PEG concentrations; the effect of these parameters mainly is related with the speciation, salting-out effect and hydrophobicity. The influence of these factors on the density, and sound velocity of the top phase was minimal, unlike its influence on the properties of the bottom phase, not isentropic compressibility and effect of PEG and Na2MoO4 concentrations on sound velocity. The evaluation of the partitioning behavior was made by experimental design, applying statistical regression analysis and analysis of variance (ANOVA). The statistical models for partition coefficient and for phase densities (and the other properties) as function of parameters with significant effects were obtained, and also a good correlation between experimental and correlated data was observed (R-Squared = 0.9379, ReO4− partition coefficient; 0.9882, bottom phase; and 0.9836 upper phase). This work is oriented to the possible application in stripping of a top phase provided for a co-extraction of rhenium and molybdenum by ATPS in acidic media or in solutions with high contend of Mo such as those provided by pressure oxidative leaching of molybdenite in basic media.

Supramolecular recognition of perrhenate is a challenging task due to therelatively large size and low charge density of this anion. In this work, we design and synthesize a family of helix-like synthetic receptors that can bind perrhenate by forming hydrogen bonds with all four oxygen atoms of the anion. Among the investigated rigid helix-forming subunit derived from 1,1′-ferrocenedicarboxylic acid, 1,3-phenylenediacetic acid and 2,2′-(ethyne-1,2-diyl)dibenzoic acid, the latter one shows the best selectivity for perrhenate recognition. However, the receptor based on 1,1′-ferrocenedicarboxylic acid demonstrates selectivity to bind chloride in a 1:2 fashion. The properties of the receptors are investigated in the acetonitrile solution by using NMR, UV–Vis, and in the solid state by single crystal X-ray analysis.

A series of new dimethyl-sulfoxide-containing pertechnetates and perrhenates of tetravalent U, Np, and Pu were synthesized and structurally characterized by the X-ray diffractometry. In all the synthesized compounds, the actinide atoms were coordinated by eight DMSO molecules with or without an extra XO4- anion in the coordination sphere. This resulted in the square antiprismatic or capped square antiprismatic coordination of An atoms. Three or four XO4- anions play the role of outer-sphere anions. The electron and IR spectra of the compounds correlated with their crystal structure.

The synthesis, structures, and characterization of two new families of trivalent lanthanide perrhenate complexes, [Ln(ReO4)(H2O)4Cl]Cl·H2O (Ln = La – Nd) (1) and [Ln(ReO4)3(H2O)2] (Ln = Tb, Ho, Er) (2), along with the expansion of a third known family, [Ln(ReO4)3(H2O)4] (Ln = Tm, Lu, Y) (3), is presented. Complex 1 is a purely inorganic member of a rare class of compounds known as cationic materials. Single crystal X-ray diffraction analysis reveals that 1 crystallizes in the P21/m space group and is comprised of two-dimensional (2D) sheets constructed from LnO4(H2O)4Cl monocapped square antiprismatic (CN = 9) lanthanide cations, 2 crystallizes in the C2 space group and is a three-dimensional (3D) structure constructed from two unique LnO6(H2O)2 square antiprismatic (CN = 8) lanthanide cations, and 3 crystallizes in the P21/n space group and is comprised of one-dimensional chains constructed from LnO4(H2O)4 square antiprismatic (CN = 8) lanthanide cations. This work provides a comprehensive study on essentially the entire lanthanide series (sans Pm) and its complexation with perrhenate at room temperature. The structural features of these complexes exhibit properties influenced by contracting ionic radii and increasing hardness upon traversing the lanthanide series.

A widely used oxidizing agent in organic chemistry with an assumed structure of “[Ag(py)2]MnO4” and its perchlorate and perrhenate analogues are studied. Their synthesis in pure form is challenging...

Low-temperature heat capacities of the 1-heptyl-3-methyl imidazolium perrhenate ionic liquids have been measured by a high-precision automated adiabatic calorimeter over the temperature range from 78 to 400 K. In this report, the standard molar heat capacity was determined to be 679.438 J K−1 mol−1. The melting temperature at 207.873 ± 0.374 K has been discovered by the heat-capacity curve. The experimental values of molar heat capacities were fitted to two polynomial equations of heat capacities (Cp,m) by least square method. Meanwhile, the thermodynamic functions (HT − H298.15), (ST − S298.15), and (GT − G298.15) were also calculated in the temperature range from 298.15 to 400 K with the interval of 5 K.

In this work, batch experiments were carried out to explore the sorption properties for perrhenate (ReO4 −, a surrogate for TcO4 −) by two types of commercial bifunctional anion-exchange resins (Purolite A530E and A532E). It is found that these two bifunctional anion-exchange resins could rapidly remove ReO4 − from aqueous solution within 150 min and the maximum sorption capacity for ReO4 − reached as high as 707 and 446 mg/g for Purolite A530E and A532E, respectively. The sorption properties were independent of pH over a wide range from 1 to 13. More importantly, both Purolite A530E and A532E exhibited excellent selectivity for the removal of ReO4 − in the presence of large excess of NO3 − and SO4 2−. Finally, the removal percentage of ReO4 − by these two resins could be >90% and 80%, respectively, from the Hanford low-level waste melter off-gas scrubber simulant stream. Such high selectivity of Purolite A530E and A532E for the removal of ReO4 − might be due to the presence of the long-chain group of –[N(Hexyl)3]+, which favored hydrophobic and large anions such as ReO4 −/TcO4 − rather than NO3 −.

A newly designed Ru(II) probe, C1 containing iodotriazole (halogen bond unit) and pendent pentafluorophenyl (π-acidic) moiety shows superior dihydrogen phosphate sensing property over perrhenate and other inorganic anions. A supramolecular polymeric chain formation by the probe through halogen bond and anion-π interactions with dihydrogen phosphate is established by solid-state structural studies. On the contrary, C1 forms a dimeric aggregation via halogen bonding interaction with perrhenate. Macroscopic investigations, such as DLS, TEM, and SEM also show the formation of supramolecular polymeric aggregated structures with phosphates, however, such aggregation is not observed in the case of perrhenate. Polymeric aggregation of C1 with phosphate is additionally supported by DOSY NMR spectroscopy. Thus, the combined cooperative action of anti-electrostatic anion–anion (phosphate-phosphate), anion-π (phosphate-π of C6F5) and halogen-bonding (phosphate and C-I of probe C1) interactions are responsible for dihydrogen phosphate induced supramolecular polymeric aggregation. Finally, the formation of larger supramolecular self-assembly in presence of dihydrogen phosphate leads to selective sensing and higher binding towards the ion over perrhenate and other inorganic anions.

Rhenium is a valuable metal in very low concentration and it is being increasingly used in industry due to its multiples properties, mainly in the aeronautics and oil industries. For this work, the PEG/CuSO 4 aqueous two phase system (ATPS) was used for the partition of perrhenate anion. For the partition tests the NH 4 ReO 4 salt was used. The effects of temperature, pH, salt concentration, PEG concentration and their interactions on the partition were analyzed by using experimental design 2 k . Moreover, density, kinematic viscosity and sound velocity were determined for the top and bottom phases. The optimal conditions obtained by the model for the perrhenate partition in the ATPS formed by PEG and CuSO 4 were 13.7% PEG 4000 ( w /w), 13% CuSO 4 (w/w) and 35 °C, obtaining a distribution coefficient, K ReO4- , of 7.72 ± 0.31. Also, an increase of K ReO4- with increasing PEG and CuSO 4 concentration was observed, i.e. their effects are significant on the perrhenate partition. On the other hand, the effects of temperature and pH do not have high significance on the partition. Of all the studied parameter, the pH had less significance on the partition. Thus, to simplify the statistical model the pH was not considered in the model. For both phases, only density is inversely proportional to pH. With exception of the sound velocity of bottom phase all properties for both phases are inversely proportional to temperature. Moreover, all properties are proportional with the PEG and CuSO 4 concentrations in both phases. The partitioning behavior was evaluated by an experimental design, applying statistical regression analysis and analysis of variance (ANOVA). The statistical model for distribution coefficient as function of the parameters with significant effects was obtained. A good agreement between experimental and correlated data was observed (R-Squared = 0.930).

For the first time the standard formation enthalpy of Bi 12.5 Nd 1.4 In 0.1 ReO 24.5 has been determined by solution calorimetry by combining the solution enthalpies of Bi 12.5 Nd 1.4 In 0.1 ReO 24.5 , 1.4NdCl 3 + 0.1InCl 3 0.1InCl 3 mixture in 2 M HCl and literature data. The lattice energy for Bi 12.5 Nd 1.4 In 0.1 ReO 24.5 has been calculated using Born-Haber cycle. The dependence of lattice energy for Bi 12.5 R 1.5 ReO 24.5 (R – rare earth element) from radius of rare earth metal was constructed. It was established that dependence was linear and had form: U lat = −129450 + 45070 r R . Linear character of experimentally obtained dependence was explained using modified variant of Kapustinskii formula obtained by us as following: U = A + Br R .

Heat capacities of sulfate, perrhenate, chloride, and iodide sodalites with the ideal formula Na8Al6Si6O24X2 (X = SO4, ReO4, Cl, I) were measured from 2 K to 300 K using a Quantum Design Physical Property Measurement System (PPMS). From the heat capacity data, the standard thermodynamic functions were determined. All four sodalites undergo a phase transition below room temperature for which thermodynamic parameters were determined. Additionally, the heat capacity of one of the constituent compounds (NaReO4) was measured.

Rhenium(VII) and molybdenum(VI) extraction with kerosene solutions of α-branched tertiary carboxylic Versatic acids derivatives containing hydrazide C(O)NHNH2 and C(O)NHNCH3)2 fragments instead of carboxyl group has been studied. Optimal extraction conditions have been determined depending on H2SO4, HCl, and extractant concentrations and composition of extracted complexes has been established. The mechanism of extraction and back extraction of perrhenate ion with ammonia solutions has been suggested.

A series of new pertechnetate, perrhenate, and perchlorate compounds of hexavalent U, Np, and Pu containing isonicotinic acid were synthesized. Their crystal structures were determined by X-ray diffractometry. In all compounds, actinide atoms are found in pentagonal bipyramidal surroundings. They are coordinated by 2 to 4 isonicotinic acid molecules which exist in zwitterionic form as a result of N atom protonation. If only 2 or 3 isonicotinic acid molecules are present in the surroundings of an actinide (An) atom, TcO4– or ReO4– anions act as monodentate ligands. Otherwise, XO4– play the role of outer sphere anions. Electron and IR spectra of the compounds correlate with their crystal structure.

Rhenium is an element that exhibits a broad range of oxidation states. Synthesis paths of selected rhenium compounds in its seventh oxidation state, which are common precursors for organic reaction catalysts, were presented in this paper. Production technologies for copper perrhenate, aluminum perrhenate as well as the ammonia complex of cobalt perrhenate, are thoroughly described. An ion exchange method, based on Al or Cu metal ion sorption and subsequent elution by aqueous perrhenic acid solutions, was used to obtain perrhenates. The produced solutions were neutralized to afford the targeted aluminum perrhenate and copper perrhenate products in high purity. The developed technologies allow one to manage the wastes from the production of these perrhenates as most streams were recycled. Hexaamminecobalt(III) perrhenate was produced by a newly developed method enabling us to produce a high purity compound in a reaction of spent hexaamminecobalt(III) chloride solution with a perrhenic acid. All prepared compounds are the basis for precursor preparation in organic catalysis.

Water-stable [Co3(tib)2(H2O)12](SO4)3 (BUC-17) was hydrothermally synthesized by adding formic acid as a modulator. The as-prepared BUC-17, whose zeta potentials were positive in pH 4.0–10.0, was used as potential adsorbent to capture ReO4− ions. The corresponding kinetics behavior and equilibrium isotherm fitted well to the pseudo-second-order and Langmuir model, in which the maximum sorption capacity of BUC-17 was 401.9 mg ReO4− g−1 sorbent at 298 K. Additionally, BUC-17 demonstrated outstanding removal activity in wide range of pH (4.0 – 10.0) and high salinity. The fixed-bed column packed with BUC-17 powder could continuously eliminate ReO4− solution, which provided the possibility to accomplish potentially large-scale application. At last, the adsorption mechanism was proposed, which was the synergism of electrostatic interactions and ion exchange between SO42− and ReO4−.

Two novel ether-based perrhenate ionic liquids [C22OnIm][ReO4](n = 1,2) were synthesized and characterized. The static properties and transport properties were measured, and the extended properties were calculated and investigated in the certain temperature range. Using the six anions of [ReO4]−, [OAc]−, [DCA]−, [NTF2]−, [SCN]− and [TfO]− as the reference ions, the values of cationic parachor for [C22OnIm]+ (n = 1,2) were obtained for the first time. The predicted values of parachor, surface tension and refractive index of 7 kinds of ionic liquids were obtained by the cationic parachor values, which are correlated quite well with their matching experimental ones. The ether-functionalization of cation could decrease the viscosity of ILs, especially 2-ethoxyethyl (2O2) group.

For the first time the heat capacities of phase Bi12.5Nd1.4In0.1ReO24.5 have been measured in the temperature range of 175–550 K. Differential scanning calorimetry has been used for measurements. The temperature dependence of heat capacity is well described by a polynomial Cop,m (T) = 542.62 + 1.5107 T – 1.0402 · 10−3 T2 – 2.7875 · 106/T2. On the basis of smoothed heat capacities the enthalpy and entropy increments were calculated (T = 175–550 K).

Aqueous solution was simulated by ammonium perrhenate and sodium sulfate in sulphuric acid system according to waste water from metallurgy process of copper and molybdenum. Molalities of perrhenate after extraction were measured at ionic strength from 0.2 to 2.0 mol kg−1 at temperature range 278.15 K to 303.15 K, using tri-n-octylamine as extractant. Optimization condition of extraction was determined in this sulphuric acid medium. The standard extraction constants K0 at various temperatures were obtained by method of polynomial approximation. Thermodynamic quantities for the extraction process were calculated.

The X-ray in-situ study of [Cu(NH3)4](ReO4)2 complex salt is carried out on heating up to 500 K. The product obtained at this temperature is a new crystalline phase [Cu(NH3)2(μ-ReO4)2] n with the following unit cell parameters: a = 14.7523(3) A, b = 5.8559(1) A, c = 5.6290(1) A, β = 111.387(1)°, V = = 452.799(2) A3, space group C2/m, Z = 2, d x = 4.386 g/cm3. The coordination polyhedron of the Cu atom is a distorted octahedron formed by two nitrogen atoms (Cu–N 2.195 A), and four oxygen atoms (Cu–О 2.306 A). The structure consists of infinite [Cu(NH3)2(μ-ReO4)2] n chains, the shortest N(H)…O distances between the chains being 2.82 A.

Acyclic tetraazametal gold(III) perrhenate complex [Au(C9H19N4)](ReO4)2 is synthesized. The 3D crystal structure of the complex is stabilized by weak secondary interactions (N–H…O, C–H…O, С–H…Au hydrogen bonds, and Au…O contacts). The translation sublattice method shows that the motif of the mutual arrangement of cations can be considered to be pseudohexagonal. The product of the thermal decomposition of [Au(C9H19N4)](ReO4)2 in a hydrogen atmosphere is a mixture of nanocrystalline phases (HCP phases based on Re and Au) with the coherent scattering region of 24 nm and 34 nm, respectively.

Analogous to the non-linear optical properties of L-alaninium perrhenate ionic crystals with three-dimensional hydrogen bonds, we have synthesized various chiral bimetallic assemblies, [CuL2][Ni(CN)4]·2H2O (Cu(II)–Ni(II)), [CuL2]3[Co(CN)6]2·5H2O·4DMSO (Cu(II)–Co(III)), [CuL2]2[Fe(CN)6]·10H2O (Cu(II)–Fe(II)), [CuL2]2[CrO4]2·5H2O (Cu(II)–Cr(VI)) and [CuL2]2[MoO4]2·3H2O·2DMSO (Cu(II)–Mo(VI)) (L = (1R,2R)-diphenylethylenediamine), determined their crystal structures at different temperatures; measured their spectroscopic and magnetic properties and confirmed their non-linear optical properties. One-dimensional Cu(II)–Ni(II) crystallizes in the P1 space group and exhibits no NLO properties. However, two-dimensional Cu(II)–Co(III) crystallizes in the P21 space group and three-dimensional Cu(II)–Fe(II) crystallizes in the C2 space group; both exhibit NLO properties. Moreover, the complexes Cu(II)–Cr(VI) and Cu(II)–Mo(VI) crystallize in polar crystals of P21 symmetry involving two-dimensional hydrogen bonding and exhibit NLO properties. These Cu(II)–Cr(VI) and Cu(II)–Mo(VI) crystals are so flexible that they exhibit anisotropic thermal negative expansion. Therefore, their second-harmonic generation efficiency makes them potentially useful as new materials for non-linear optics.

The crystal structure of Cu+Re7+O4 is capable of a quasi-reversible incorporation of C3H7OH molecules. A room-temperature reaction between CuReO4 and C3H7OH under oxidizing conditions leads to the formation of a novel metal-organic hybrid compound Cu2+(C3H7OH)2(ReO4)2. Upon heating under reducing conditions, this compound transforms back into CuReO4, albeit with ReO2 and metallic Cu as by-products. The crystal structure of Cu(C3H7OH)2(ReO4)2 solved from single-crystal X-ray diffraction (Pbca, a=10.005(3) A, b=7.833(2) A, and c=19.180(5) A) reveals layers of corner-sharing CuO6-octahedra and ReO4-tetrahedra, whereas isopropyl groups are attached to both sides of these layers, thus providing additional connections within the layers through hydrogen bonds. Cu(C3H7OH)2(ReO4)2 is paramagnetic down to 4 K because the spatial arrangement of the Cu2+ half-filled orbitals prevents magnetic superexchange. The paramagnetic effective moment of 2.0(1) μB is slightly above the spin-only value and typical for Cu2+ ions.

It is significant for environment and human health to develop new materials for the sorption of radioactive technetium. We report herein a novel method to synthesize surface ion-imprinted magnetic microspheres for efficient capture of technetium ions. Specifically, perrhenate anion as the structural surrogate for pertechnetate anion, was employed as template to prepare ion-imprinted magnetic microsphere by “one-pot” radical polymerization and quaternization. The sorption behavior is closely related with the surface chemical composition: the more nitrogen content, the higher sorption efficiency. The sorption is an exothermic spontaneous sorption process and kinetically followed pseudo-second-order model. A sorption capacity of 62.8 mg of Re/g could be achieved at 298.15 K and pH = 6. Compared with non-imprinted composites, imprinted microspheres showed higher selectivity, faster kinetics, and larger sorption capacity of perrhenate ions. This work may provide a promising approach for the efficient sorption of pertechnetate.

Perrhenate of the tetraazamacrocyclic complex of gold(III) [Au(C14H22N4)]ReO4 is synthesized. The crystal structure of the compound is determined by single crystal X-ray diffraction. The crystallographic data are as follows: а = 7.733(2) A, b = 11.368(2) A, c = 11.685(2) A, α = 116.23°, β = 104.26°, γ = 94.96°; V = 870.3(3) A3, space group P(–1), Z = 2, dcalc = 2.647 g/cm3, R = 0.0245. The packing of the complex is comprised of double stacks of cations and chains of anions linked into two-dimensional layers due to weak intermolecular interactions (non-classical hydrogen bonds C–H…O, C–H…Au, C–H…π and the Au…Au contacts). The thermal decomposition of the obtained compound in the hydrogen atmosphere is studied. According to the powder X-ray diffraction data, the product of the reduction of the synthesized salt is a mixture of nanocrystalline phases of Re and Au with the coherent-scattering regions of 17 nm and 13 nm respectively.

By controlling the extent of hydrolysis during the self-assembly process of a zwitterionic-based ligand with uranyl cations, we observed a structural evolution from the neutral uranyl-organic framework [(UO2)2(TTTPC)(OH)O(COOH)]·1.5DMF·7H2O (SCU-6) to the first cationic uranyl-organic framework with the formula of [(UO2)(HTTTPC)(OH)]Br·1.5DMF·4H2O (SCU-7). The crystal structures of SCU-6 and SCU-7 are layers built with tetranuclear and dinuclear uranyl clusters, respectively. Exchangeable halide anions are present in the interlaminar spaces balancing the positive charge of layers in SCU-7. Therefore, SCU-7 is able to effectively remove perrhenate anions from aqueous solution. Meanwhile, the H2PO4(-)-exchanged SCU-7 material exhibits a moderate proton conductivity of 8.70 × 10(-5) S cm(-1) at 50 °C and 90% relative humidity, representing nearly 80 times enhancement compared to the original material.

Oxo–rhenium compounds, such as perrhenate salts, have demonstrated preferable activity in catalyzing the deoxydehydration (DODH) reaction in the presence of reductants. Here, the first computational details of the reported DODH mechanisms are presented using the density functional theory (DFT) (M06/6-311+G(d,p)/LANL2DZ) to investigate the conversion of a vicinal diol into the corresponding alkene by ReO4– as a catalyst. The DFT studies were carried out to evaluate the DODH mechanisms, from the energy point of view, for the conversion of phenyl-1,2-ethanediol to styrene by perrhenate anion in the presence of PPh3 as a reductant through a detailed comparison of two potential pathways including pathway A and pathway B. Pathway A includes the sequence of condensation of oxo–Re(VII) with diol before the reduction of Re(VII) to Re(V), whereas pathway B involves the reduction of oxo–Re(VII) to oxo–Re(V) before the condensation process. In pathway B, two basic routes (B1 and B2) are possible, which can take place...

Aqueous solution was simulated by ammonium perrhenate and sodium sulfate as impurties in sulphuric acid system. Molalities of perrhenate after extraction were measured at impurity ionic strength from 0.2 to 2.0 mol × kg−1 in aqueous phase at 278.15 K, 283.15 K, 288.15 K, 293.15 K, 298.15 K, and 303.15 K using N235. The best extraction condition was determined in this sulphuric acid medium. Standard extraction constants K0 at various temperatures were obtained by polynomial approximation method. Some microcosmic phenomena were investigated in the extraction process.

The acetonitrile solution of NH 4 ReO 4 added to methanol/acetonitrile solution of Cu(NO 3 ) 2 with bis(pyrazol-1-yl)methane leads to the blue heterobimetallic [Cu(bpzm) 2 ][ReO 4 ] 2 ( 1 ) complex in which perrhenate is linked via oxygen with copper(II) ion. The reaction with bis(3,5-dimethylpyrazol-1-yl)methane under the same conditions gave [Cu(bdmpzm) 2 ][NO 3 ]·[ReO 4 ]·CH 3 CN ( 2 ) complex in which perrhenate exists as counterion. Both complexes were structurally characterized and in solid state by IR, UV–Vis–NIR spectroscopy and magnetic susceptibility measurements. The magnetic data indicated paramagnetism of both complexes with the weak magnetic short-range interactions and without frustration of the spins below 2 K.

Carbon-supported rhenium–palladium catalysts (Re–Pd/C) effectively transform aqueous perchlorate, a widespread drinking water pollutant, via chemical reduction using hydrogen as an electron donor at ambient temperature and pressure. Previous work demonstrated that catalyst activity and stability are heavily dependent on solution composition and Re content in the catalyst. This study relates these parameters to changes in the speciation and molecular structure of Re immobilized on the catalyst. Using X-ray spectroscopy techniques, we show that Re is immobilized as ReVII under oxic solution conditions, but transforms to a mixture of reduced, O-coordinated Re species under reducing solution conditions induced by H2 sparging. Under oxic solution conditions, extended X-ray absorption fine structure (EXAFS) analysis showed that the immobilized ReVII species is indistinguishable from the dissolved tetrahedral perrhenate (ReO4–) anion, suggesting outer-sphere adsorption to the catalyst surface. Under reducing sol...

A series of imidazolium perrhenate ionic liquids (IPILs) have been synthesized and used as efficient catalysts for the oxidation of sulfides to sulfones with aqueous hydrogen peroxide under mild conditions. Various sulfones are obtained in good to excellent yields. IPILs are stable and can be reused at least ten times without detectable activity loss. Furthermore, this system provides a reasonably environmentally benign chemical process in terms of potential industrial application.

The crystal structure was determined and the physicochemical properties were studied for tetrapropylammonium pertechnetate and perrhenate. Pr4NMO4 (M = Tc, Re) are isostructural and crystallize as colorless prismatic crystals in the orthorhombic system, space group Pna21, Z = 4. For M = Tc at 25°C, a = 13.22(4) A, b = 12.35(3) A, c = 10.13(4) A; for M = Re at −120°C, a = 13.169(2) A, b = 12.311(2) A, c = 10.107(1) A. The Re-O distances are 1.677(12), 1.704(5), 1.719(4), and 1.739(11) A. Each anion in this structure has four neighboring cations with Re…N distances of 5.06–5.34 A. The solubility product of Pr4NTCO4 is (6.19 ± 0.50) × 10−5 mol2/L2. The Gibbs energy of dissolution of [(C3H7)4N]TcO4 in dilute aqueous solutions is 24.0 ± 0.5 kJ/mol. The association constant K1 for (Pr4N+)…(TcO4−) in water and aqueous solutions is 10.8 ± 0.7 L/mol. The solubility of Pr4NTcO4 increases with the solution acidity, similarly to the solubility of Bu4NTcO4. Upon precipitation of Pr4NTcO4 from model solutions containing (2.0–7.5) × 10−2 mol/L Tc in 3–4 M HNO3, (2.0–7.5) × 10−8 mol/L 239PuO2(NO3)2, and 5.7 mCi/L 106Ru(NO)(NO3)3, the technetium decontamination factors from 239Pu and 106Ru were (0.5–1.5) × 102 and (6.0–7.5) × 102, respectively.

The silver complex with phenazine [Ag(Phz)2(H2O)]ReO4 (Phz is C12H8N2) has been synthesized, and its crystal structure has been determined. The crystals are triclinic: space group \(P\bar 1\), a = 9.587(1) A, b = 10.875(1) A, c = 11.668(1) A, α = 104.98(1)°, β = 103.87(1)°, γ = 92.94(1)°, V = 1132.6(2) A3, Z = 2, ρcalc = 2.160 g/cm3. The structure is composed of the [Ag(Phz)2(H2O)]+ silver cationic complexes and ReO4− anions. The Ag+ ion is coordinated by two nitrogen atoms of independent phenazine molecules and the water oxygen atoms and has a T-shaped coordination (Ag-Nav 2.223 A, Ag-Ow 2.498(8) A). Phenazine, being an electron-donor ligand, forms columns due to π-π stacking interaction between the aromatic groups. The water molecules form hydrogen bonds with the oxygen atoms of water molecules of neighboring complexes and with oxygen atoms of the ReO4− anions.

Heteropolymetallic complexes [(salen)Ti(ReO 4 ) 2 ] ( 1 ) and [{(salen)Ti(ReO 4 )} 2 (μ-O)] ( 2 ) are easily obtained in high yields via reaction of [(salen)TiCl 2 ] and [{(salen)TiCl 2 } 2 (μ-O)] with (Me 3 SiO)ReO 3 , respectively (where, salen = (S,S)- N , N ′-bis(3,5-di- tert -butylsalicylidene)cyclohexane-1,2-diamine dianion). The structure of complex 2 was established by single-crystal X-ray diffraction. The tetrahedral geometry of the ReO 4 − anion links the dititanium unit of {(salen)Ti} 2 (μ-O) in the axial positions. The Re–O–Ti bridge angles range from 146.1(2) to 162.6(2) with a Re⋯Ti separation of 3.780 A. Complexes 1 and 2 are capable of catalytic oxidation of sulfides with t BuOOH.

By using quantum chemical calculations, the most probable structures of the anionic complex species dodecabenzylbambus[6]uril–ClO4−, dodecabenzylbambus[6]uril–MnO4−, dodecabenzylbambus[6]uril–TcO4− and dodecabenzylbambus[6]uril–ReO4− were derived. In these four complexes, each of the considered anions, included in the macrocyclic cavity, is bound by 12 weak hydrogen bonds between methine hydrogen atoms on the convex face of glycoluril units and the respective anion. Further, the corresponding interaction energies of the investigated four anionic complexes were calculated; the absolute values of these calculated energies increase in the series of ReO4− < TcO4− < MnO4− < ClO4−.

The efficient removal of pertechnetate (TcO4(-)) anions from liquid waste or melter off-gas solution for an alternative treatment is one of the promising options to manage (99)Tc in legacy nuclear waste. Safe immobilization of (99)Tc is of major importance because of its long half-life (t1/2 = 2.13 × 10(5) yrs) and environmental mobility. Different types of inorganic and solid-state ion-exchange materials have been shown to absorb TcO4(-) anions from water. However, both high capacity and selectivity have yet to be achieved in a single material. Herein, we show that a protonated version of an ultrastable zirconium-based metal-organic framework can adsorb perrhenate (ReO4(-)) anions, a nonradioactive surrogate for TcO4(-), from water even in the presence of other common anions. Synchrotron-based powder X-ray diffraction and molecular simulations were used to identify the position of the adsorbed ReO4(-) (surrogate for TcO4(-)) molecule within the framework.