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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.

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.

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.

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.

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.

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.

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.

We describe a multidentate tripodal ligand in which three pendant arms carrying di(2-picolyl)amine units are linked to the ortho positions of a tris(o-xylyl) scaffold, providing N(CH[subscript 2]-o-C[subscript 6]H[subscript 4]CH[subscript 2]N(CH2py)[subscript 2])[subscript 3] (L). Reaction of L with CuCl[subscript 2] in the presence of hexafluorophosphate anion afforded blue cubes of [(CuCl)[subscript 3]L](PF[subscript 6])[subscript 3]·5H[subscript 2]O (1). Crystallographic studies of 1 revealed that the three symmetry-related arms each coordinate a {Cu[superscript II]Cl} unit, and two molecules of 1 are connected to one another through a Cu(μ-Cl)[subscript 2]Cu bridge, extending the molecular structure to form a two-dimensional (2-D) layer. These 2-D layers pack in an ABCABC... fashion with PF[subscript 6]– anions located in between. Reaction of 1 with a stoichiometric amount of perrhenate ion afforded blue plates of [(CuCl)[subscript 3]L](PF[subscript 6])(ReO[subscript 4])[subscript 2]·3H[subscript 2]O (2). Compound 2 has the same lattice structure as 1, but the tricopper unit backbone now traps one ReO[subscript 4]– anion through Coulombic interactions. In addition, three molecules of 2 are bridged by a perrhenate ion, forming a Cu[subscript 3](μ[superscript 3]-ReO[subscript 4]) cluster, to give a different 2-D structure displaying a rare tridentate bridging ReO[subscript 4]– mode. Thus, in addition to classic perrhenate trapping through weak Coulombic interactions, 2 represents an exceptional example in which the ReO[subscript 4]– anion is immobilized in an extended framework through tight covalent interactions. The interlamellar PF[subscript 6]– anions in 1 can be exchanged with other anions including perrhenate, perchlorate, or periodate. The structural similarity between perrhenate and pertechnetate makes these materials of potential interest for pertechnetate trapping.

The reaction of lanthanide nitrates with cucurbit[n]urils (CBn, n = 5, 6, 7) under hydrothermal conditions in the presence of perrhenic acid and, for some of them, other reactants such as KNO(3) yielded 14 new complexes which were crystallographically characterized and present some original features. Four of the five complexes with CB5 are capsules closed by a lanthanide ion (Ce, Sm, Gd) on one side and potassium on the other and have an encapsulated bridging nitrate ion, but the fifth is a monodimensional polymer with both bidentate portals of CB5 complexed to ytterbium. All eight CB6 complexes (Ce, Pr, Sm, Gd, Yb, Lu) and the single ytterbium complex of CB7 (the first lanthanide complex of CB7 to be characterized) involve perrhenate encapsulation, in a form which is either bridging the lanthanide ions coordinated at each tridentate portal, or terminal when the CB is bidentate and the cation is further from the portal, or even noncoordinating in one case. The orientation of the cation in the cavity varies depending upon its coordination mode, as well as the nature of the shortest contacts in the cavity. Some original architectures are described, in particular a sinuous chain, ribbonlike assembly in a cerium complex of CB6 and a novel samarium-CB6 sandwich complex. The ubiquitous encapsulation of ReO(4)(-) in CB6 and CB7 may open new perspectives for the investigation of anion complexation by these macrocycles.

Heterobimetallic complexes of a vanadium(V) and rhenium(VII) combination connected by a mu-oxido bridge [LVO(mu-O)ReO 3].H 2O [H 2L = N, N'-ethylene bis(salicylideneimine) (H 2salen) and its methoxy derivative] ( 1, 2) are reported. The compounds have been prepared by a single-pot synthesis in which the precursor [V (IV)OL] complexes are allowed to be oxidized aerially in the presence of added perrhenate. The oxidized [V (V)OL] (+) species accommodate the ReO 4 (-) anion in their vacant coordination site, trans to the terminal oxido group, providing the complexes 1 and 2. The later generates a binuclear oxovanadium(V) compound [H 2en][(TBC)VO(mu-TBC) 2OV(TBC)].5H 2O ( 3) when treated with tetrabromocatechol. Single crystal X-ray diffraction analysis and (1)H NMR spectroscopy have been used to establish their identities. In compound 2, the Re(1)-O(11)-V(1) bridge angle is barely linear [170.2(3) degrees ] with a Re...V separation of 3.9647(9) A. The redox behavior of 1 and 2 are quite interesting, each undergoing two reductions both in the positive potential range at E 1/2 = 0.59 (process I) and E 1/2 = 0.16 V (process II) versus Ag/AgCl reference (corresponding potentials are 0.59 and 0.18 V for 2). Process I has a single-electron stoichiometry involving the [VO(salen)] part of the complexes as established by combined coulometry-Electron Paramagnetic Resonance (EPR) experiments which provide an eight-line isotropic EPR pattern at room temperature ( = 1.967; = 87 x 10 (-4) cm (-1)), characteristic of an unpaired electron being coupled to a vanadium nuclear spin ( (51)V, I = 7/2). The almost linear V-O-Re bridge in 1 and 2 allows this unpaired electron to interact effectively with the neighboring Re nuclear spin, leading to familiar " two-line pattern" superhyperfine coupling ( A ( (185,187)Re) = 20.7 x 10 (-4) cm (-1)). Process II, on the other hand, is based on a Re(VII/VI) electron transfer as confirmed by differential pulse and normal pulse voltammetric experiments.

Compound cis,fac-[Mo(eta3-allyl)(CO)2(Hdmpz)3]BAr'4 (1) (Hdmpz = 3,5-dimethylpyrazole, Ar' = 3,5-bis(trifluoromethyl)phenyl) undergoes rapid substitution of one of the pyrazole ligands by anions, including the low nucleophilic ReO4-, a reaction that afforded [Mo(OReO3)(eta3-allyl)(CO)2(Hdmpz)2] (2), structurally characterized by X-ray diffraction. The new compounds fac-[Mn(CO)3(Hdmpz)3]BAr'4 (4a) and fac-[Mn(CO)3(HtBupz)3]BAr'4 (4b) (HtBupz = 3(5)-tert-butylpyrazole) also undergo pyrazole substitution with most anions, and the product from the reaction with nitrate was crystallographically characterized. Compounds 4a,b were found to be substitutionally stable toward perrhenate, and the adducts [Mn(CO)3(Hdmpz)3].[ReO4] (7a) and [Mn(CO)3(HtBupz)3].[ReO4].[Bu4N].[BAr'4] (7b), crystallographically characterized, display hydrogen bonds between one of the perrhenate oxygens and the N-H groups of two of the pyrazole ligands. The structurally similar adduct [Re(CO)3(Hdmpz)3].[ReO4] (8) was found to result from the interaction of [Re(CO)3(Hdmpz)3]BAr'4 with perrhenate. The reaction of [Re(OTf)(CO)5] with 3,5-dimethylpyrazole (Hdmpz) afforded [Re(CO)5(Hdmpz)]OTf (9). The reaction of 9 with Hdmpz and NaBAr'4 yielded [Re(CO)4(Hdmpz)2]BAr'4 (10), which was found to be unstable toward chloride anion. In contrast, the new compound fac,cis-[Re(CO)3(CNtBu)(Hdmpz)2]BAr'4 (11) is stable in solution in the presence of different anions. Binding constants for 11 with chloride, bromide, and nitrate are 1-2 orders of magnitude lower than those found for these anions and rhenium tris(pyrazole) hosts, indicating that the presence of the third pyrazole ligand is crucial. Compounds fac-[Re(CO)3(HPhpz)3]BAr'4 (14) (HPhpz = 3(5)-phenylpyrazole) and fac-[Re(CO)3(HIndz)3]BAr'4 (15) (HIndz = indazole) are, in terms of anion binding strength and selectivity, inferior to those with dimethylpyrazole or tert-butylpyrazole ligands.

This work is part of an effort to develop chelating agents for stable binding and easy conjugation of Re-188 to biologically interesting structures. Starting from the well-known in vivo stability of [(188)ReO(DMSA)(2)](-), we want to exploit this coordination system for the design of (188)ReO(V) chelates, which are stable toward reoxidation to perrhenate and toward ligand exchange under all conditions of radiopharmaceutical development. Therefore, a new type of tetradentate ligand has been synthesized by bridging two molecules of N,N'-diisobutyl-2,3-dimercaptosuccinamide with N-(3-aminopropyl)propane-1,3-diamine. The resulting stereoisomeric tetrathiolato S(4) ligand of composition ((i)()Bu)(2)N(O)C-C(SH)-C(SH)-C(O)NH-(CH(2))(3)-NH-(CH(2))(3)-NHC(O)-C(SH)-C(SH)-C(O)N((i)Bu)(2) forms anionic five-coordinate oxorhenium(V) complexes by a ligand-exchange reaction of NBu(4)[ReOCl(4)] in methanol. In the absence of a base, the compounds were isolated as "betaine", [ReO(S(4))], with the protonated nitrogen of the bridge serving as an internal "counterion". Two representatives have been fully characterized in both the solid and solution states and found to adopt the expected square-pyramidal coordination geometry. The equatorial plane is formed by four thiolate sulfur atoms, whereas the oxygen occupies the apical position. The orientation of the metal oxo group is exo in relation to the carbamido groups in both isomers. Both complexes are stereoisomeric regarding the junction of the triamine chain.

We report the synthesis, structural, and spectroscopic characterization of a series of uranium(IV)-perrhenato complexes. Three isostructural complexes with general formula [U(ReO4)4(L)4] (where L = tri-n-butylphosphine oxide/TBPO (2), triethyl phosphate/TEP (3), or tri-iso-butyl phosphate/TiBP (4)), have been synthesized, both through the photoreduction of ethanolic {UO2}2+ solutions and also via a novel U(IV) starting material, U(ReO4)4.5H2O (1). Compound 1 has also been used in the preparation of [U(ReO4)4(TPPO)3(CH3CN)].2CH3CN (5) and [U(ReO4)(DPPMO2)3(OH)][ReO4]2.2CH3CN (6), where TPPO represents triphenylphosphine oxide and DPPMO2 represents bis(diphenylphosphino)methane dioxide. All six complexes have been spectroscopically characterized using NMR, UV-vis-NIR, and IR techniques, with 2, 3, 5, and 6 also fully structurally characterized. The U atoms in compounds 2-6 all exhibit eight-coordinate geometry with up to four perrhenate groups in addition to three (DPPMO2 and TPPO) or four (TEP, TiBP, TBPO) coordinated organic ligands. In the case of compounds 5 and 6, the coordination of eight ligands to the U(IV) center is completed by the binding of a solvent molecule (CH3CN) and OH-, respectively. Solid-state physical analysis (elemental and thermogravimetric) and infrared spectroscopy are in agreement with the structural studies. The crystallographic data suggest that the strength of the U(IV)-O-donor ligand bonds decreases across the series R3PO > [ReO4]- > (RO)3PO. Solution-state IR and 31P NMR spectroscopy appear to be in agreement with these solid-state results.

Reaction between cationic units of carboxylate-bridged diruthenium complexes [Ru(2)(mu-O(2)CR)(4)](+) (R = Me, CMePh(2), CMe(3), CH(2)CH(2)OMe, C(Me)=CHEt, C(6)H(4)-p-OMe, Ph) and tetrabutylammonium perrhenate gives complexes with different arrangements in the solid state. Thus, the compounds Ru(2)(mu-O(2)CR)(4)(ReO(4)) [R = Me (1), CMePh(2) (2), CMe(3) (3), CH(2)CH(2)OMe (4), C(Me)=CHEt (5), C(6)H(4)-p-OMe (6), Ph (7)] have polymeric structures with the diruthenium units linked by perrhenate ligands in the axial positions. The structures of complexes 3.THF and 4 were established by single-crystal X-ray diffraction. The tetrahedral geometry of the ReO(4)(-) anion permits the formation of a chain close to the linearity. In contrast to the polymeric chains observed in complexes 1-7, the reaction of [Ru(2)(mu-O(2)CPh)(4)](+) with NBu(4)ReO(4) also affords the compounds Ru(2)(mu-O(2)CPh)(4)(ReO(4))(H(2)O) (8) and NBu(4)[Ru(2)(mu-O(2)CPh)(4)(ReO(4))(2)] (9) depending on the reaction conditions. The structure of 8 consists of cationic and anionic units, [Ru(2)(mu-O(2)CPh)(4)(H(2)O)(2)](+) and [Ru(2)(mu-O(2)CPh)(4)(ReO(4))(2)](-), linked by hydrogen bonds, which give a three-dimensional net. The structure of complex 9.0.5H(2)O has an anionic unit similar to that of 8, whose counterion is NBu(4)(+). The Ru-Ru bond distances are slightly longer in [Ru(2)(mu-O(2)CPh)(4)(ReO(4))(2)](-) than in the polymeric compounds Ru(2)(mu-O(2)CR)(4)(ReO(4)). The magnetic behavior owes to the existence of zero-field splitting (ZFS) and a weak antiferromagnetic coupling. The experimental data are fitted with a model that considers the ZFS effect using the Hamiltonian (D) = SDS. The weak antiferromagnetic coupling is introduced as a perturbation, using the molecular field approximation.

Technetium-99 (beta-, t(1/2) = 2.15 x 10(5) years) is produced in a 6% fission yield from fission reactors. Technetium-99 continues to be of major concern at various nuclear sites because of its mobility in its most common chemical form during the reprocessing cycle and in the environment. Under these oxic aqueous environments the chemical form of Tc is typically Tc(VII)O4-, which is difficult to remove. Methods for pertechnetate removal to date have mixed results and pose further environmental concerns. Utilization of new cyclotriveratrylene host materials for the extraction of pertechnetate from 0.9% saline into nitromethane has shown high selectivity and efficiency. A deep-cavity host, tris[cyclopentadienyliron(II) arene]cyclotriguiasylene (2), has shown95% extraction of pertechnetate and perrhenate into nitromethane from saline in the presence of competing anions, outperforming previously reported materials.

Neutral and asymmetrical hydrazido(3-)rhenium(V) heterocomplexes of the type [Re(eta(2)-L(4))(L(n))(PPh(3))] (eta(2)-L(4) = NNC(SCH(3))S; H(2)L(1) = S-methyl beta-N-((2-hydroxyphenyl)ethylidene)dithiocarbazate, 1, H(2)L(2) = S-methyl beta-N-((2-hydroxyphenyl)methylidene)dithiocarbazate, 2) are prepared via ligand-exchange reactions in ethanolic solutions starting from [Re(V)(O)Cl(4)](-) in the presence of PPh(3) or from [Re(V)(O)Cl(3)(PPh(3))(2)]. The distorted octahedral coordination sphere of these compounds is saturated by a chelated hydrazido group, a facially ligated ONS Schiff base, and PPh(3). Reduction-substitution reactions starting from [NH(4)][Re(VII)O(4)] in acidic ethanolic mixtures containing PPh(3) and H(2)L(n) (or its dithiocarbazic acid precursor H(3)L(4)) produce another example of chelated hydrazido(3-) rhenium(V) derivative, namely [Re(eta(2)-L(4))Cl(2)(PPh(3))(2)], 3. On the contrary, the N-methyl-substituted dithiocarbazic acid H(2)L(3) reacts with perrhenate to give the known nitrido complex [Re(N)Cl(2)(PPh(3))(2)]. Rhenium(V) complexes incorporating the robust eta(2)-hydrazido moiety represent key intermediates helpful for the comprehension of the reaction pathway which generates nitridorhenium(V) species starting from oxo precursors. An essential requirement for the stabilization of such chelated hydrazido-Re(V) units is the triple deprotonation at the hydrazine nitrogens, thereby providing efficient pi-electron circulation in the resulting five-membered ring. The thermal stability of these units is affected by the nature of the anchoring donor, thione sulfur ensuring stronger chelation than nitrogen and oxygen. The eta(2)-hydrazido complexes are characterized by conventional physicochemical techniques, including the X-ray crystal structure determination of 1 and 3.

[ReO(ppme)X] (where ppme(2-) is 2,5-diazo-N,N'-dimethylhexyl-1,6-bis(phenylphosphinate), X = Br0.3Cl0.7) has been synthesized via a substitution reaction and structurally characterized. The coordination geometry is a distorted octahedron and one phosphinate coordinates cis and the other trans to the oxo O atom. This coordination mode is conserved in all [ReOppmeX] complexes synthesized in this study. [ReO(ppme)Cl] has been prepared by a reduction/complexation reaction from [NH4][ReO4]. [ReO(ppme)Cl] reacts with thiocyanate and benzene thiolate forming [ReO(ppme)X] (X = (-)NCS, (-)SC6H5), but the one-pot synthesis of the respective ternary thiolate complexes from perrhenate was not successful. The reduction/complexation reaction of a thiol, H2ppmeCl4, and perrhenate resulted in the formation of [H3ppme][ReO(SR)4], the reaction of which with [ReO(ppme)Cl] does not lead to [ReO(ppme)SR] in high yields.

The reaction of uranyl and lanthanide nitrates with cucurbit[6]uril (CB6) in the presence of perrhenic acid and under hydrothermal conditions yields the novel heterometallic uranyl-lanthanide molecular complexes [UO2Ln(CB6)(ReO4)2(NO3)(H2O)7](ReO4)2 (Ln = Sm, Eu, Gd, Lu). Both metal cations are bound to carbonyl groups of the same CB6 portal, one for UO2(2+) and two for Ln3+. The uranium atom is also bound to one monodentate perrhenate ion and three aquo ligands, while the lanthanide is bound to one monodentate perrhenate and one nitrate ions, and four aquo ligands. Not only are these complexes rare examples of ReO4(-) bonding to f element ions, but the perrhenate bound to Ln is included in the CB6 cavity, thus providing the first case of inclusion of a tetrahedral oxoanion in this macrocycle.

The reduction of perrhenate, molybdate and pertechnetate with 2-hydrazinopyridine dihydrochloride in methanol has led to the preparation of a class of complexes containing the {M(eta(1)-NNC(5)H(4)NH(x)())(eta(2)-HNNH(y)()C(5)H(4)N)} core, represented by [TcCl(3)(NNC(5)H(4)NH)(HNNC(5)H(4)N)] (2), [ReCl(3)(NNC(5)H(4)NH)(HNNC(5)H(4)N)] (3), and [MoCl(3)(NNC(5)H(4)NH)(HNNHC(5)H(4)N)] (6). The reaction of 3 with NEt(3) results in the formation of [HNEt(3)][[ReCl(3)(NNC(5)H(4)N)(HNNC(5)H(4)N)].H(2)O (4) by deprotonation of the pyridine nitrogen site. Similarly, the reduction of perrhenate with 2-hydrazino-2-imidazoline hydrobromide has led to the preparation of the analogous [ReCl(3)(NNC(3)H(4)N(2)H)(HNNHC(3)H(4)N(2)H)] (5). Reaction of 3 with pyridine-2-thiol and pyrimidine-2-thiol yields two structurally characterized derivatives with a modified {Re(eta(1)-NNC(5)H(4)N)(eta(2)-HNNC(5)H(4)N)} core, [Re(C(5)H(4)NS)(2)(NNC(5)H(4)N)(HNNC(5)H(4)N)] (8) and [Re(C(4)H(3)N(2)S)(2)(NNC(5)H(4)N)(HNNC(5)H(4)N)] (9), respectively. Reaction of 6 with pyrimidine-2-thiol led to the isolation of the analogous [Mo(C(4)H(3)N(2)S)(2)(NNC(5)H(4)N)(HNNHC(5)H(4)N)] (11) and the seven-coordinate monohydrazine core complex [Mo(C(4)H(3)N(2)S)(3)(NNC(5)H(4)N)].CH(2)Cl(2) (12). In similar fashion, the reaction of 2 with pyridine-2-thiol yielded a complex structurally analogous to 8, [Tc(C(5)H(4)NS)(2)(NNC(5)H(4)N)(HNNC(5)H(4)N)] (7). Crystal data for 3, C(10)H(10)Cl(3)N(6)Re: triclinic, Po, a = 7.527(2) A, b = 7.599(2) A, c = 13.118(3) A, alpha = 106.55(3) degrees, beta = 90.28(3) degrees, gamma = 93.83(3) degrees, V = 717.4(4) A(3), Z = 2. For 4, C(16)H(27)Cl(3)N(7)ORe: orthorhombic, P2(1)2(1)2(1), a = 7.503(2) A, b = 10.3643(2) A, c = 30.1590(5) A, V = 2345.20(6) A(3), Z = 2. For 5, C(6)H(12)Cl(3)N(8)Re: monoclinic, P2(1)/n, a = 9.093(2) A, b = 11.105(2) A, c = 14.295(3) A, beta = 94.71(3) degrees, V = 1438.6(7) A(3), Z = 4. For 6, C(10)H(11)Cl(3)N(6)Mo: monoclinic, P2(1)/c, a = 15.366(3) A, b = 7.804(2) A, c = 12.378(3) A, beta = 95.92(3) degrees, V = 1476.4(5) A(3), Z = 4. For 7, C(20)H(17)N(8)S(2)Tc: monoclinic, P2(1), a = 8.827(2) A, b = 9.278(2) A, c = 13.304(3) A, beta = 98.92(3) degrees, V = 1076.5(5) A(3), Z = 2, 2564 reflections. For 8, C(20)H(17)N(8)S(2)Re: monoclinic, P2(1), a = 8.848(2) A, b = 9.190(2) A, c = 13.293(3) A, beta = 98.89(3) degrees, V = 1067.9(5) A(3), Z = 2. For 9, C(18)H(15)N(10)S(2)Re: monoclinic, P2(1), a = 8.796(2) A, b = 9.008(2) A, c = 13.208(3) A, beta = 97.90(3) degrees, V = 1036.6(5) A(3), Z = 2. For 12, C(18)H(15)N(9)S(3)Cl(2)Mo: monoclinic, P2(1)/n, a = 10.52900(10) A, b = 15.1116(3) A, c = 15.8193(3) A, beta = 108.4790(10) degrees, V = 2387.23(7) A(3), Z = 4. Complexes 2 and 3 serve as models for the binding of Tc(V)-oxo and Re(V)-oxo species to hydrazinonicotinamide (HYNIC)-conjugated chemotactic peptides. Furthermore, since the use of the pyrimidinethiol coligand in the {(99m)Tc-HYNIC-peptide} radiochemical species results in favorable pharmacokinetics, the thiolate derivatives 8 and 9 provide models for possible modes of interaction of metal-hydrazine cores with coligands in the radiopharmaceutical reagents.

Crystals of the layered metal organic framework solid Pb[B(Im)4](NO3)(nH2O) can undergo exchange of the nitrate for perrhenate, a model for pertechnetate, forming Pb[B(Im)4](ReO4). We can monitor this reaction by 207Pb solid-state NMR and can isolate single crystals of the resultant material through growth in the presence of an excess of perrhenate. Such a synthetic metal-organic framework solid represents a new candidate for pertechnetate-sequestering materials.

Heterometallic cerium(IV) perrhenate, permanganate, and molybdate complexes containing the imidodiphosphinate ligand [N(i-Pr2PO)2](-) have been synthesized, and their reactivity was investigated. Treatment of Ce[N(i-Pr2PO)2]3Cl (1) with AgMO4 (M = Re, Mn) afforded Ce[N(i-Pr2PO)2]3(ReO4) (2) or Ce2[N(i-Pr2PO)2]6(MnO4)2 (3). In the solid state, 3 is composed of a [Ce2{N(i-Pr2PO)2}6(MnO4)](+) moiety featuring a weak Ce-OMn interaction [Ce-OMn distance = 2.528(8) Å] and a noncoordinating MnO4(-) counteranion. While 3 is stable in the solid state and acetonitrile solution, it decomposes readily in other organic solvents, such as CH2Cl2. 3 can oxidize ethylbenzene to acetophenone at room temperature. Treatment of 1 with AgBF4, followed by reaction with [n-Bu4N]2[MoO4], afforded [Ce{N(i-Pr2PO)2}3]2(μ-MoO4) (4). Reaction of trans-Ce[N(i-Pr2PO)2]2(NO3)2 (5), which was prepared from (NH4)2Ce(NO3)6 and K[N(i-Pr2PO)2], with 2 equiv of [n-Bu4N][Cp*MoO3] yielded trans-Ce[N(i-Pr2PO)2]2(Cp*MoO3)2 (6). 4 can catalyze the oxidation of methyl phenyl sulfide with tert-butyl hydroperoxide with high selectivity. The crystal structures of complexes 3-6 have been determined.

We report the synthesis and structural characterization of [UO(2)(ReO(4))(DPPMO(2))(2)][ReO(4)] and [UO(2)(Cl)(DPPMO(2))(2)][Cl] (where DPPMO(2) = bis(diphenylphosphino)methane dioxide). In both complexes, the linear uranyl dication is coordinated to two bidentate DPPMO(2) ligands in the equatorial plane with one coordinated and one non-coordinated anion (either perrhenate or chloride). We have also prepared the pertechnetate analogue, and, through (31)P and (99)Tc NMR, we have shown that the cation, [UO(2)(TcO(4))(DPPMO(2))(2)](+), is stable in solution.

A new method for the synthesis of low to intermediate oxidation state rhenium complexes containing a bifunctional ligand has been developed. Reaction of [ReO(4)](-) with substituted phenylhydrazines and triphenylphosphine in acetonitrile in the presence of HCl allows the isolation of [ReCl(2)(NNC(6)H(4)-4-R)(NCCH(3))(PPh(3))(2)] (where R = OCH(3), Cl, or CO(2)CH(3)). The substituted hydrazine acts as both a reductant and source of a monodentate diazenide ligand. The compounds have all been characterized in the solid state by X-ray crystallography and in the solution state by NMR, electrospray mass spectrometry, and HPLC. Cyclic voltammetry measurements show that the mono-diazenide complexes undergo a reversible oxidation.

The complexes of ReO 2 + and ReO(OH) 2+ with 1,4,8,11-tetraazacyclotetradecane (cyclam) and 1,4,8,11-tetraazacyclotetradecan-2-one (O 1 cyclam) have been synthesized and characterized. The complexes were prepared by ligand exchange reactions of the macrocycles with a variety of starting compounds including ReOCl 3 (PPh 3 ) 2 and ReO 2 (en) 2 Cl. The ReO(OH) 2+ complexes have been structurally characterized.

The rhenium(V) oxo oxalate complex (HBpz 3 )ReO(C 2 O 4 ) (HBpz 3 =hydridotris(1-pyrazolyl)borato) has been synthesized in three steps from potassium perrhenate. It has been characterized spectroscopically and its molecular structure determined by X-ray crystallography. When irradiated with UV light, the oxo oxalate complex undergoes an internal redox reaction, predominantly lining carbon dioxide and generating a reactive rhenium complex.

Electrochemical oxidation of Pd(tmp), in the presence of the perrhenate ion affords the new molecular conductor [Pd(tmp)] 2 [ReO 4 ]. The compound is composed of partially oxidized (+1/2) Pd(tmp) cations stacked metal-over-metal and surrounded by chains of ReO 4 anions. Single-crystal room-temperature conductivity along the needle axis averages 30 Ω −1 cm −1 and may be fit to an expression that describes a semiconductor with temperature-dependent carrier mobility. ESR measurements confirm the tmp ligand as the site of oxidation

Electrochemical oxidation of (5,10,15,20-tetramethylporphyrinato) copper (II), Cu (tmp), in the presence of the perrhenate ion affords the new molecular conductor [Cu(tmp)] 2 [ReO 4 ]. The compound is composed of partially oxidized (+1/2) Cu (tmp) cations stacked metal-over-metal and surrounded by chains of ReO 4 anions

Perrhenatoiron(III) tetraphenylporphyrin has been isolated as its toluene solvate and characterized by using magnetic susceptibility, IR and Mossbauer spectroscopy, and single-crystal X-ray diffraction. Space group P1

The reaction between Re2(C6H5NCOCH3)4Cl2 and water in air yields a blue compound [Re4(C6H5NCOCH3)6(Cl)(μ-O)(μ-OH)(MeOH)3][ReO4]2. It crystallizes in a triclinic cell with a = 12.356(3) A, b = 14.820(6) A, c = 20.064(6) A, α = 103.38(3)°, β = 91.61(2)°, γ = 110.37(2)°, V = 3327(2) A3, and Z = 2. The X-ray crystallography revealed an unprecedented tetranuclear structure together with two perrhenate ions. The tetranuclear dication is formed by two quadruply bonded dirhenium units linked through an oxygen ligand and a hydroxy ligand. One unit uses two rhenium atoms and the other unit uses only one rhenium atom to form a Re−Re−O−Re−OH five-membered ring. The formula of this compound was further confirmed by mass spectral analysis.

A new layered compound (Sb4O5)(ReO4)2 was prepared by thermal decomposition of SbOReO4·2H2O. The structure contains cationic layers of (Sb4O5)2+ in which each antimony atom is coordinated by three oxygen atoms in a trigonal-pyramid geometry. Tetrahedral perrhenate ions are between these cationic layers.

The full kinetic pH profile for the base-promoted decomposition of MTO to CH(4) and ReO(4)(-) was examined with the inclusion of new data at pH 7-10. Spectroscopic and kinetic data gave evidence for mono- and dihydroxo complexes: MTO(OH(-)) and MTO(OH(-))(2). Parallel unimolecular eliminations of methane from these species account for the rate-pH profile; the respective rate constants are MTO(OH(-)), k = 4.56 x 10(-)(5) s(-)(1) and MTO(OH(-))(2), k = 2.29 x 10(-)(4) s(-)(1) at 25 degrees C. Some kinetic data were acquired with electrospray mass spectrometry to monitor the buildup in the concentration of perrhenate ions. Reliable signals for each of the isotopomers of ReO(4)(-) were obtained by this method with initial MTO concentrations of 160mgr;M.

Complexes of technetium with diphosphonate ligands are widely used for the imaging and diagnosis of bone disease and most especially metastatic bone cancer. Analogous complexes of radioactive rhenium ((186)Re) with the ligand H(4)HEDP, 1,1-hydroxyethylidenediphosphonate, have been shown to be effective palliatives for the treatment of the intense pain associated with metastatic bone cancer. We have synthesized several of these analogs using nonradioactive Re and have structurally characterized them using EXAFS (extended X-ray absorption fine structure) spectroscopy. One complex synthesized via the substitution reaction of HEDP with trans-[(py)(4)(O)(2)Re]Cl in absolute ethanol appears to be the 1:1 salt of the tris-HEDP complex anion with the starting Re cation, [(py)(4)(O)(2)Re][Re(H(2)HEDP)(3)]. Three other materials, all synthesized via reduction of perrhenate by stannous chloride in the presence of excess H(4)HEDP ligand, are quite different in structure from the material formed by substitution. The principal difference is that each of these contains Re-Re bonds and is formulated as oligomers. The material with a large excess of reductant has Re-Re bonds of ca. 2.4 Å and is best modeled as a linear tetramer of rhenium atoms bridged by HEDP ligands which also bind an equivalent number of tin atoms with additional HEDP ligands. It is formulated as Li(x)()[Re(4)(OH)(2)Sn(4)(HEDP)(12)]. The material formed with the least amount of reducing agent is best modeled as a triangular cluster of rhenium atoms bicapped by two HEDP ligands and bridged to three tin atoms by HEDP to form a complex Li(x)()[Re(3)Sn(3)(HEDP)(8)]. It also has Re-Re bonds but of a significantly longer distance, ca. 2.8 Å. A material with an intermediate amount of reducing agent, prepared in a manner most closely resembling the medically effective palliative agent, appears to contain a mixture of these, and perhaps other, oligomers.

Le compose du titre cristallise dans le groupe d'espace P3c1. Affinement de la structure jusqu'a 0,031. Re(II) montre une geometrie de coordination grossierement octaedrique

The results of studies to monitor the rate of reaction of perrhenates and pertechnetates with various radical species, to spectrophotometrically characterize the Tc(VI) and Re(IV) transients produced by reaction with the hydrated electron, and to obtain information about the rate and mechanism of decay of these transients are reported. The Re(VI) transient was found to be more reactive than the Tc(VI) transient. The perrhenate was also found to react with OH, while no such reaction is noted for the pertechnetate. 28 refs.

A partir de [Os(N)R 2 Cl 2 ] − ou [Ru(N)R 2 Cl 2 ] − ou R=Me ou CH 2 SiMe 3 et AgSO 4 ou K 2 CO 3 ou AgReO 4 on prepare les complexes [Os(N)R 2 (SO 4 )], [Os(N)R 2 (ReO 4 ) 2 ] [Os(N)R 2 (CO 3 ) 2 ] et [Ru(N)R 2 Cl 2 ]