Rhenium Cluster Complexes Research Articles

Comprehensive study of hexarhenium cluster complex Na4[{Re6Te8}(CN)6] – In terms of a new promising luminescent and X-ray contrast agent

Octahedral rhenium cluster complexes may have considerable potential as therapeutic and diagnostic drugs due to their luminescent and X-ray contrast properties, as well as their ability to generate singlet oxygen upon photoirradiation. However, their potential biological effects and toxicity in vitro and in vivo are rather far from being understood. Thus, the aim of our research was to study cytotoxicity, intracellular localization and cellular uptake/elimination kinetics in vitro, biodistribution and acute intravenous toxicity in vivo of a complex Na4[{Re6Te8}(CN)6] as the promising compound for biomedical application. The results have demonstrated that the complex penetrates through cell membranes with the maximum accumulation in cells in 24h of incubation and have low toxic effects in vitro and in vivo. The median lethal dose (LD50) of intravenously administrated Na4[{Re6Te8}(CN)6] is equal to 1082±83mg/kg. These findings will be useful for future development of cluster-based agents for different biomedical applications.

Structure of ionic cluster complex [{Er(H2O)2(phen)2(μ-OH)}2][Re4Te4(CN)12]•13H2O

The rhenium cluster complex [{Er(H2O)2(phen)2(μ-OH)}2][Re4Te4(CN)12]•13H2O (1) was synthesized and structurally characterized. The structure of the salt was determined by single-crystal X-ray diffraction analysis. Compound 1 contains a new dimeric cationic fragment [{Er(H2O)2(phen)2(μ-OH)}] 2 4+ .

Cellular internalization and morphological analysis after intravenous injection of a highly hydrophilic octahedral rhenium cluster complex - a new promising X-ray contrast agent.

The octahedral cluster compound Na2 H8 [{Re6 Se8 }(P(C2 H4 CONH2 )(C2 H4 COO)2 )6 ] has been shown to be highly radio dense, thus becoming a promising X-ray contrast agent. It was also shown that this compound had low cytotoxic effect in vitro, low acute toxicity in vivo and was eliminated rapidly from the body through the urinary tract. The present contribution describes a more detailed cellular internalization assay and morphological analysis after intravenous injection of this hexarhenium cluster compound at different doses. The median lethal dose (LD50 ) of intravenously administrated compound was calculated (4.67 ± 0.69 g/kg). Results of the study clearly indicated that the cluster complex Hn [{Re6 Se8 }(P(C2 H4 CONH2 )(C2 H4 COO)2 )6 ]n-10 was not internalized into cells in vitro and induced only moderate morphological alterations of kidneys at high doses without any changes in morphology of liver, spleen, duodenum, or heart of mice. Copyright © 2016 John Wiley & Sons, Ltd.

Synthesis, structure and luminescence properties of new chalcogenide octahedral rhenium cluster complexes with 4-aminopyridine [{Re6Q8}(4-NH2-py)6]2+

Two new cationic octahedral rhenium cluster complexes [{Re6Q8}(4-NH2-py)6]2+ (Q=S, Se; 4-NH2-py = 4-aminopyridine) were synthesized by reactions of cesium salts of cluster anions [{Re6Q8}Br6]4−/3− with molten 4-aminopyridine. Both complexes were separated as salts with Br− as counterions and the structure of [{Re6S8}(4-NH2-py)6]Br2·6DMF was revealed by X-ray single-crystal diffraction analysis. The compounds were characterized by elemental analysis, energy dispersive X-ray, IR, NMR, and luminescence spectroscopies.

Crystal structure of the ionic cluster complex (2,2′-bipyH2)2[Re4Se4(CN)12]·(2,2′-bipy)·7H2O

A rhenium cluster complex (2,2′-bipyH2)2[Re4Se4(CN)12] · (2,2′-bipy)·7H2O (1) is obtained and characterized. The compound crystallizes in a monoclinic space group C2/c with the unit cell parameters: a = 16.9191(6) A, b = 18.7458(6) A, c = 19.0139(5) A, β = 108.568(1)°, V = 5716.6(3) A3, Z = 4, d x = 2.291 g/cm3. The crystal structure is a packing of bipyridylium cations (2,2′-bipyH2)2+, cluster anions [Re4Se4(CN)12]4−, bipyridyl molecules, and crystal water molecules, which are linked together by a system of hydrogen bonds.

A family of octahedral rhenium cluster complexes trans-[{Re6Q8}(PPh3)4X2] (Q = S or Se, X = Cl, Br or I): Preparation and halide-dependent luminescence properties

Four new octahedral rhenium cluster complexes trans-[{Re6Q8}(PPh3)4X2] (Q=S, Se; X=Cl, I) were synthesized by reaction of cesium salts of cluster anions [{Re6Q8}X6]4−/3− with molten triphenylphosphine. The compounds were characterized by elemental and X-ray structural analyses. Emission spectra and photophysical characteristics for all new compounds and earlier described trans-[{Re6Q8}(PPh3)4Br2] were obtained showing a dependence of the emission maximum wavelength, quantum yield and lifetime values from cluster ligand environment.

Polymerisable octahedral rhenium cluster complexes as precursors for photo/electroluminescent polymers

Re-containing cluster complexes have been developed and polymerised to generate photo/electroluminescent materials, which can be used to construct PLEDs.

Synthesis, structure and DFT calculations of the first bioctahedral chalcohalide rhenium cluster complex (Et4N)4(Me2NH2)2[Re12CS17Br6

The first example of dodecanuclear chalcohalide rhenium cluster complex, (Et4N)4(Me2NH2)2[Re12CS17Br6] (1), has been synthesized by reaction of polymeric cluster solid Re12CS17 with excess of Et4NBr in boiling DMF. The compound was characterized by a set of methods, including IR and UV–Vis spectroscopy, elemental analysis, EDS, mass-spectrometry, single-crystal X-ray diffraction analysis, and quantum-chemical calculations. The crystal structure presents an interesting case of 1D supramolecular architecture based on notably short Br⋯Br interactions of 3.432Å between the terminal bromide trans-ligands of adjacent [Re12CS17Br6]6− cluster anions. The DFT calculations performed for the [Re12CS17Br6]6− anion showed good agreement between calculated and experimental data.

Biodistribution of Rhenium Cluster Complex K4[Re6S8(CN)6] in the Body of Laboratory Rats

We studied the biodistribution of luminescent octahedral rhenium cluster complex K4[Re6S8(CN)6], a promising agent for photodynamic therapy. It was shown that rhenium complex [Re6S8(CN)6](4-)is mainly accumulated in the liver, the central organ of metabolism, and can be excreted by the kidneys. The cluster complex was also accumulated in the spleen in significant amount, which makes it a promising agent for creation of preparations for diagnostics and treatment of lymphoproliferative disorders. The mean lethal dose of the cluster complex was 0.38 g/kg.

Crystal structure of the ionic bioctahedral cluster complex [Ni(NH3)6]2.5NH4[Re12CS17(CN)6]·8.5H2O

A rhenium cluster complex [Ni(NH3)6]2.5·NH4[Re12CS17(CN)6]·8.5H2O is obtained and structurally described. The compound crystallizes in the triclinic space group P-1 with the unit cell parameters: a = 11.0856(13) A, b = 15.242(2) A, c = 21.232(3) A, α = 90.158(4)°, β = 97.439(4)°, γ = 90.051(4)°, V = 3557.3(8) A3, Z = 2, dcalc = 3.287 g/cm3. The crystal structure represents a packing of [Ni(NH3)6]2+ and NH4+ cations, [Re12CS17(CN)6]6− cluster anions, and crystallization water molecules bound by a system of hydrogen bonds.

Novel crystal structures of potassium salts of chalcohydroxo cluster complexes [Re6Q8(OH)6]4− (Q = S or Se)

Potassium salts of chalcohydroxo rhenium cluster complexes [Re6Q8(OH)6]4− (Q = S or Se) with the composition K4[Re6S8(OH)6]·4H2O (1) and K4[Re6Se8(OH)6]·5H2O (2) are produced by evaporation of the corresponding strongly alkaline aqueous solutions. The composition of the compounds is determined by the single crystal X-ray diffraction study. The compounds crystallize in the triclinic space group P\(\bar 1\) with the following unit cell parameters: a = 8.408(2) A, b = 9.096(2) A, c = 9.222(2) A, α = 95.110(4)°, β = 107.085(4)°, γ = 113.026(4)°, V = 603.5(3) A3, Z = 1, dx = 4.689 g/cm3 (for 1) and a = 8.782(3) A, b = 9.155(4) A, c = 9.325(4) A, α = 105.481(7)°, β = 109.266(6)°, γ = 99.104(6)°, V = 656.6(4) A3, Z = 1, dx = 5.305 g/cm3 (for 2).

Preparation of a Family of Hexanuclear Rhenium Cluster Complexes Containing 5-(Phenyl)tetrazol-2-yl Ligands and Alkylation of 5-Substituted Tetrazolate Ligands

The preparation of two new families of hexanuclear rhenium cluster complexes containing benzonitrile and phenyl-substituted tetrazolate ligands is described. Specifically, we report the preparation of a series of cluster complexes with the formula [Re(6)Se(8)(PEt(3))(5)L](2+) where L = benzonitrile, p-aminobenzonitrile, p-methoxybenzonitrile, p-acetylbenzonitrile, or p-nitrobenzonitrile. All of these complexes undergo a [2 + 3] cycloaddition with N(3)(-) to generate the corresponding [Re(6)Se(8)(PEt(3))(5)(5-(p-X-phenyl)tetrazol-2-yl)](+) (or [Re(6)Se(8)(PEt(3))(5)(2,5-p-X-phenyltetrazolate)](+)) cluster complexes, where X = NH(2), OMe, H, COCH(3), or NO(2). Crystal structure data are reported for three compounds: [Re(6)Se(8)(PEt(3))(5)(p-acetylbenzonitrile)](BF(4))(2)•MeCN, [Re(6)Se(8)(PEt(3))(5)(2,5-phenyltetrazolate)](BF(4))•CH(2)Cl(2), and [Re(6)Se(8)(PEt(3))(5)(2,5-p-aminophenyltetrazolate)](BF(4)). Treatment of [Re(6)Se(8)(PEt(3))(5)(2,5-phenyltetrazolate)](BF(4)) with HBF(4) in CD(3)CN at 100 °C leads to protonation of the tetrazolate ring and formation of [Re(6)Se(8)(PEt(3))(5)(CD(3)CN)](2+). Surprisingly, alkylation of the phenyl and methyl tetrazolate complexes ([Re(6)Se(8)(PEt(3))(5)(2,5-N(4)CPh)](BF(4)) and [Re(6)Se(8)(PEt(3))(5)(1,5-N(4)CMe)](BF(4))) with methyl iodide and benzyl bromide, leads to the formation of mixtures of 1,5- and 2,5-disubstituted tetrazoles.

Structure of a new molecular rhenium cluster complex: trans-{[Ni(NH3)5]2×[Re6Se8(CN)4(OH)2]}·6H2O

Counter-diffusion of the aqueous solution of Cs2.75K1.25[Re6Se8(CN)4(OH)2] and a water-ammonia solution of NiCl2 afforded crystals of a rhenium cluster complex trans-{[Ni(NH3)5]2[Re6Se8(CN)4(OH)2]}·6H2O. The structure of the complex is determined by single crystal X-ray diffraction. In the structure, nickel atoms have an octahedral coordination environment involving nitrogen atoms of five NH3 ligands and one CN ligand of the cluster anion. The anion has two bridging CN ligands in the trans-positions

Electron vacancy localization in a single-molecular switch based on a twelve-nuclear rhenium cluster

Data of 13C NMR and quantum chemical methods is used to show that a change in the oxidation degree of 12-nuclear rhenium cluster complexes [Re12CS17(CN)6]n− from n = 6 to n = 8 leads to electron vacancy localization on the rhenium atoms surrounding the central carbon atom.

Sugar‐Decorated Dendritic Nanocarriers: Encapsulation and Release of the Octahedral Rhenium Cluster Complex [Re6S8(OH)6]4−

The encapsulation of a nanometer-sized octahedral anionic rhenium cluster complex with six terminal hydroxo ligands [Re(6)S(8)(OH)(6)](4-) in maltose-decorated poly(propylene amine) dendrimers (POPAM, generation 4 and 5) has been investigated. Ultrafiltration experiments showed that maximal loading capacity of the dendrimers with the cluster complex is achieved after about ten hours in aqueous solution. To study the inclusion phenomena, three different methods have been applied: UV/Vis, time-resolved laser-induced fluorescence spectroscopy (TRLFS), and laser-induced liquid bead ion desorption mass spectrometry (LILBID-MS). From the results obtained, it could be concluded that: a) the hydrolytic stability of the rhenium cluster complex is significantly enhanced in the presence of dendritic hosts; b) the cluster anions are preferentially bound inside the dendrimers; c) the number of cluster complexes encapsulated in the dendrimers increases with rising dendrimer generation. On average, four to five cluster anions can preferentially be captured in the interior of sugar-coated dendritic carriers. An asymptotic progression of the release of cluster complexes from the loaded dendrimers was observed under physiologically relevant conditions (isotonic sodium chloride solution: approximately 93 % within 4 days for loaded POPAM-G4-maltose; approximately 86 % within 4 days for loaded POPAM-G5-maltose). These encapsulation and release properties of maltose-decorated nanocarriers imply the possibility for the development of the next generation of dendritic nanocarriers with specific targeting of destined tissue for therapeutic treatments.

Cover Picture: Sugar-Decorated Dendritic Nanocarriers: Encapsulation and Release of the Octahedral Rhenium Cluster Complex [Re6S8(OH)6]4− (Chem. Asian J. 12/2010)

Cover Picture: Sugar-Decorated Dendritic Nanocarriers: Encapsulation and Release of the Octahedral Rhenium Cluster Complex [Re6S8(OH)6]4− (Chem. Asian J. 12/2010)

Dodecanuclear rhenium cluster complexes with an interstitial carbon atom: Synthesis, structures and properties of two new compounds K 6[Re 12CS 17(OH) 6]·4H 2O and Na 12Re 12CS 17(SO 3) 6·48.5H 2O

The dodecanuclear rhenium anionic complex with terminal hydroxo ligands [Re 12CS 17(OH) 6] 6− was obtained by the reaction of K 6[Re 12CS 17(CN) 6]·20H 2O with molten KOH at 300 °C. The cluster complex was crystallized as a potassium salt from aqueous solution. The reaction between K 6[Re 12CS 17(OH) 6]·4H 2O and Na 2S 2O 4 in water under reflux results in the formation of the complex Na 12[Re 12CS 17(SO 3) 6]·48.5H 2O. Both new compounds were characterized by single-crystal X-ray diffraction, elemental analyses and IR spectroscopy. The electronic structure of [Re 12CS 17(OH) 6] 6− was also elucidated by DFT calculations.

Crystal Structure of (H3O)4[(C2H5)4N]6 [Th2Cl4(H2O)12O]3[Re4Se4(CN)12

Crystals of the rhenium cluster complex (H3O)4[(C2H5)4N]6[Th2Cl4(H2O)12O]3[Re4Se4(CN)12]4 are obtained in an acidic (HCl) aqueous solution by the reaction of cluster salt K4[Re4Se4(CN)12]·6H2O with ThCl4 and (C2H5)4NCl. Single crystal X-ray analysis shows that the title compound is ionic and crystallizes in the cubic crystal system (a = 22.7322(3) A, V = 11746.93(27) A3, Z = 2, I4 3m space group, R = 0.0350). It contains [Th2Cl4(H2O)12O]2+ cations with two thorium atoms bonded to each other through the bridging oxygen atom forming an angle of 180° in the structure.

ChemInform Abstract: Tellurium-Containing Rhenium Cluster Complexes

Synthetic procedures as well as the structures and some properties of tetrahedral and octahedral tellurium-containing rhenium cluster complexes are reported. Crystal chemistry of various types of structure is discussed.

A new hexanuclear rhenium cluster complex with six terminal acetate ligands: Synthesis, structure, and properties of K 4[Re 6S 8(CH 3COO) 6]·8H 2O

A room-temperature reaction between [Re 6S 8(OH) 6] 4− and acetic acid in an aqueous solution resulted in the substitution of all terminal hydroxo groups by acetate ligands, affording a new hexanuclear anionic rhenium cluster complex [Re 6S 8(CH 3COO) 6] 4−. The complex was isolated as a potassium salt with the composition of K 4[Re 6S 8(CH 3COO) 6]·8H 2O ( 1) and characterized by X-ray single-crystal diffraction and elemental analyses, IR, 1H NMR, UV–Vis, and luminescence spectroscopies.