Octahedral Cluster Complexes Research Articles

MoII Cluster Complex‐Based Coordination Polymer as an Efficient Heterogeneous Catalyst in the Suzuki–Miyaura Coupling Reaction

The design and preparation of highly active heterogeneous palladium catalysts is attracting ever‐increasing attention. In this paper, we report on the self‐assembly of palladium centers and an octahedral molybdenum cluster complex bearing phosphine terminal ligands. This leads to a coordination polymer exhibiting high catalytic activity in the Suzuki–Miyaura cross‐coupling reaction. The coordination polymer achieved a turnover number of 15800 in a reaction of deactivated aryl bromides with phenylboronic acid. Because metal clusters represent rare building blocks for the preparation of heterogeneous palladium catalysts, this work points to new structural motives that can be utilized to develop highly active heterogeneous catalysts.

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.

Studying the Effect of a Composition of the Cluster Core in High-Radiopacity Cluster Complexes of Rhenium on Their Acute Toxicity In Vivo.

An in vivo study was performed to evaluate the dependence of acute toxicity of high-radiopacity and luminescent octahedral cluster complexes of rhenium after intravenous injection on a composition of the cluster core. Changes in mouse body weight, water and food consumption, degree of intoxication, and morphological changes in the visceral organs were studied after intravenous injection of the following cluster complexes with various internal ligands (S, Se, or Te): Na4[{Re 6 Te 8 }(CN)6], Na4[{Re 6 Se 8 }(CN)6], and Na4[{Re 6 S 8 }(CN)6]. The Na4[{Re 6 S 8 } (CN)6] cluster complex was shown to be the safest for animals.

ChemInform Abstract: Octahedral Clusters with Mixed Inner Ligand Environment: Self‐Assembly, Modification and Isomerism

AbstractReview: 106 refs.

Prospects of molybdenum and rhenium octahedral cluster complexes as X-ray contrast agents

Investigation of new X-ray contrast media for radiography is an important field of science since discovering of X-rays in 1895. Despite the wide diversity of available X-ray contrast media the toxicity, especially nephrotoxicity, is still a big problem to be solved. The octahedral metal-cluster complexes of the general formula [{M6Q8}L6] can be considered as quite promising candidates for the role of new radiocontrast media due to the high local concentration of heavy elements, high tuning ability of ligand environment and low toxicity. To exemplify this, the X-ray computed tomography experiments for the first time were carried out on some octahedral cluster complexes of molybdenum and rhenium. Based on the obtained data it was proposed to investigate the toxicological proprieties of cluster complex Na2H8[{Re6Se8}(P(CH2CH2CONH2)(CH2CH2COO)2)6]. Observed low cytotoxic and acute toxic effects along with rapid renal excretion of the cluster complex evidence its perspective as an X-ray contrast media for radiography.

Octahedral clusters with mixed inner ligand environment: Self-assembly, modification and isomerism

Octahedral cluster complexes of transition metals are associated with halogen or chalcogen inner ligands to form edge-bridged {M6(μ2-X)12} or face-capped {M6(μ3-X)8} cluster cores. The partial exchange of X atoms leading to mixed inner ligand environment invokes a distortion of metallic cluster, reduction of symmetry as well as an isomerism of the cluster cores. This review summarizes preparation methods of mixed ligand cluster complexes with the general formulas [{M6(μ2-X)12}L6] n or [{M6(μ3-X)8}L6] n and their structural features.

Rhenium octahedral clusters in mesoporous MIL-101: luminescence and sorption properties

Rhenium octahedral cluster complexes were immobilized into the cages mesoporous chromium(III) terephthalate MIL-101 in two ways: by the inclusion of anionic clusters as guests and by the coordination of cluster complexes through ditopic organic ligands (4,4′-bipyridyl) to metal atoms of the framework. The influence of the cluster complex—metal-organic matrix type of bonding on luminescence and sorption properties was studied. It was shown that the intensity of luminescence of the hybrid compound in which the cluster complexes are coordinated through ditopic organic ligands is considerably lower than that of the inclusion compound of cluster complexes in the coordination polymer cages.

Crystal structure of a new modification of the cyanide-bridged copper(I) coordination compound [CuCN(bpy)] n

The hydrothermal reaction of CuCN and bpy in the presence of an octahedral cluster complex K2.75Cs1.25[Re6Se8(CN)4(OH)2]·H2O affords a cyanide-bridged chain coordination polymer [CuCN(bpy)]n (bpy — 2,2′-bipyridyl) (1). The structure is monoclinic, space group C2/c, a = 22.848(2) A, b = 7.7182(8) A, c = 14.4331(13) A, β = 127.805(2)°, V = 2010.9(3) A3, Z = 8, dx = 1.623 g/cm3. Copper atoms have a tetrahedral coordination environment formed by N atoms of the bpy molecule as well as N and C atoms of ambidentate bridging CN ligands.

Crystal structure of the octahedral cluster complex trans-[{Re6S8}(pyz)4I2]·2pyz

The cluster complex of the composition trans-[{Re6S8}(pyz)4I2]· 2pyz (pyz is pyrazine) is obtained by the reaction of Cs4[{Re6S8}I6] with molten pyrazine. The compound crystallizes in the triclinic space group \(P\bar 1\) with the following unit cell parameters: a = 9.0562(7) A, b = 10.2502(7) A, c = 12.6783(9) A, α = 98.537(3)°, β = 107.573(2)°, γ = 106.943(3)°, V = 1036.6(1) A3, Z = 1, dcalc = 3.377 g/cm3. The crystal structure is built of trans-[{Re6S8}(pyz)4I2] cluster complexes and uncoordinated pyrazine molecules.

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.

Synthesis and structures of new octahedral heterometal rhenium-osmium cluster complexes

New octahedral anionic heterometal rhenium-osmium cluster complexes [Re5OsSe8(OH)6]3− and [Re4Os2Se8(OH)6]2− were synthesized starting from [Re5OsSe8Cl6]3− and [Re4Os2Se8Cl6]2−, respectively. They were isolated as salts of the compositions Cs3[Re5OsSe8(OH)6] · 11H2O (I), K3[Re5OsSe8(OH)6] · 7H2O (II), and K2[Re4Os2Se8(OH)6] · 3H2O (III). The protonation of the terminal OH ligands of [Re5OsSe8(OH)6]3− in an aqueous solution resulted in crystallization of a neutral complex [Re5OsSe8(H2O)3(OH)3] · 12H2O (IV). The compounds have been characterized by single-crystal X-ray diffraction analysis. The luminescence properties of [Re5OsSe8(OH)6]3− and [Re4Os2Se8(OH)6]2− were studied. In addition, the electronic structures of the complexes were elucidated by DFT calculations.

Synthesis and crystal structure of the octahedral cyano-bridged cluster complex β-[{Ni(NH3)5}2{Re6Te8(CN)6}]·4H2O

The rhenium cyano-bridged cluster complex with a composition of β-[{Ni(NH3)5}2{Re6Te8(CN)6}]−4H2O is obtained and structurally characterized. The compound pound crystallizes in the P\( P\bar 1 \) triclinic space group with the unit cell parameters: a = 9.997(2) A, b = 10.423(2) A, c = 11.714(2) A, α = 100.92(3)°, β = 111.87(3)°, γ = 98.05(3)°, V = 1082.1(4) A3, Z = 1, dcalc = 4.072 g/cm3. The rhenium atoms of the {Re6Te8} cluster core are coordinated by CN ligands to form the [Re6Te8(CN)6]4− cluster; two nitrogen atoms of CN ligands trans-positioned with respect to each other are coordinated to Ni atoms in the {Ni(NH3)5}2+ fragments to form the molecular complexes of [{Ni(NH3)5}2}Re6Te8(CN)6}]. The crystal structure is the H-bonded packing of these molecular complexes and crystallization water molecules.

First molecular octahedral rhenium cluster complexes with terminal As- and Sb-donor ligands

Six new molecular octahedral cluster complexes with the general formulas trans-[{Re6(μ3-Q)8}(EPh3)4Br2] and fac-[{Re6(μ3-Q)7(μ3-Br)}(AsPh3)3Br3] (Q = S or Se and E = As or Sb) were synthesized by the reactions of the cesium salts of the [{Re6(μ3−S)8}Br6]4−, [{Re6(μ3-Se)8Br6]3−, and [{Re6(μ3-Q)7(μ3-Br)}Br6]3− anions with molten triphenylarsine (AsPh3) and triphenylantimony (SbPh3), respectively. The compositions and structures of the resulting complexes were established by single-crystal X-ray diffraction and confirmed by elemental analysis and vibrational spectroscopy. The compositions and structures of the complexes depend on the composition of the cluster core in the starting salts. The luminescence spectra were recorded for powdered samples of all these compounds and the earlier described complexes trans-[{Re6Q8}(PPh3)4Br2] and fac-[{Re6Q7Br}(PPh3)3Br3].

Synthesis, Structures and Properties of Cluster Complexes [H 3 O(Ph 3 PO) 3 ] 2 [Mo 6 Cl 14 ] and [H(Ph 3 PO) 2 ] 2 [Re 6 S 6 Br 8

New cluster compounds [H3O(Ph3PO)3]2[Mo6Cl14] (I) and [H(Ph3PO)2]2[Re6S6Br8] (II) have been prepared by the reaction of a acetonitrile solution of triphenylphosphane oxide Ph3PO with octahedral cluster complexes of molybdenum (H3O)2Mo6Cl14·6H2O and rhenium K2Re6S6Br8, respectively, (with addition of several drops of HBr). The structures and properties of the products were studied by single-crystalX-ray diffraction and NMR and luminescence spectroscopic methods. The compounds studied are characterized by strong hydrogen bonds with O–O distances of 2.45–2.51 Å (I) and 2.34–2.41 Å (II); unusual H-bonded cationic trimers, [H3O(Ph3PO)3]+, were found in compound I. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Synthesis and structure of a new molecular octahedral cluster complex Mo6Se8(Ph3P)6·2H2O

Mo6Se8(Ph3P)6·2H2O cluster complex has been synthesized and its structure has been defined. The compound is triclinic, space group P1¯, with unit cell parameters a = 14.3356(5) A, b = 15.7882(4) A, c = 25.3949(8) A, = 95.9750(10)°, β = 91.1030(10)°, γ= 112.2570(10)°, V = 5279.8(3) A3, Z = 2, ρcalc = 1.772 g/cm3. The complex has a molecular structure. The molybdenum atoms of the {Mo6Se8} cluster nucleus are coordinated by the phosphorus atoms of triphenylphosphine molecules.

Octahedral aqua fluoride rhenium cluster complexes K[Re 6S 8F 3(H 2O) 3] · 7H 2O, H 3O[Re 6Se 8F 3(H 2O) 3] · 7H 2O and [Re 6Q 8F 2(H 2O) 4] · 12H 2O (Q = S, Se): Synthesis and structure

Four new octahedral cluster complexes – K[Re 6S 8F 3(H 2O) 3] · 7H 2O ( 1), H 3O[Re 6Se 8F 3(H 2O) 3] · 7H 2O ( 2) and [Re 6Q 8F 2(H 2O) 4] · 12H 2O (Q = S ( 3), Se ( 4)), have been synthesized using the reaction of rhenium chalcobromide complexes K 4[Re 6S 8Br 6] · 2H 2O and Cs 3[Re 6Se 8Br 6] · H 2O with molten KHF 2 and further crystallization form aqueous solutions under different conditions. All compounds synthesized were characterized by X-ray single-crystal diffraction, chemical analysis, and IR spectra.

Synthesis and crystal structure of the octahedral cluster complex [Th(DMSO)8Cl][Re6Se7Cl7

A cluster complex of the composition [Th(DMSO)8Cl][Re6Se7Cl7] has been obtained by interaction of ThCl4 solution in DMSO with a water solution of K3[Re6Se7Cl7] and KCl. The compound crystallizes in the rhombic space group Pbcm with unit cell parameters a = 12.262(2) A, b = 19.653(6) A, c = 23.603(6) A, V = 5688(2) A3, Z = 4, d calc = 3.282 g/cm3. The structure is built from centrosymmetric cluster anions [Re6Se7Cl7]3− and complex cations [Th(DMSO)8Cl]3+ possessing mirror-plane symmetry, half of the DMSO ligands being doubly disordered.

Octahedral rhenium cluster complexes with organic ligands: Synthesis, structure and properties of [Re 6Q 8(3,5-Me 2PzH) 6]Br 2 · 2(3,5-Me 2PzH) (Q = S, Se)

Two new octahedral cluster complexes – [Re 6S 8(3,5-Me 2PzH) 6]Br 2 · 2(3,5-Me 2PzH) ( 1) and [Re 6Se 8(3,5-Me 2PzH) 6]Br 2 · 2(3,5-Me 2PzH) ( 2), where 3,5-Me 2PzH is 3,5-dimethylpyrazole, have been synthesized using reaction of rhenium chalcobromide complexes Cs 4[Re 6S 8Br 6] · 2H 2O and Cs 3[Re 6Se 8Br 6] · H 2O, respectively, with molten 3,5-dimethylpyrazole. Both compounds synthesized were characterized by X-ray single-crystal diffraction and chemical analysis, IR and luminescent spectra.

(iPr3P)6Rh6H12]2+: a high-hydride content octahedron that bridges the gap between late and early transition metal clusters.

Treatment of [(iPr3P)2Rh(nbd)][Y] {nbd = norbornadiene, Y = B{3,5-(CF3)2C6H3}4- [B(ArF)4] or 1-H-closo-CB11Me11-} with H2 (ca. 4 atm) results in the isolation, in moderate yield, of the octahedral cluster complex [(iPr3P)6Rh6H12][Y]2 1. The cluster (for both anions) has been characterized by NMR, mass spectroscopy, and X-ray crystallography. These show 1 to have 12 edge-bridging hydrogen atoms, and the structure bears more resemblance to clusters of the early transition metals with pi-donor ligands than those of the late transition metals with pi-acceptor ligands. Intermediate complexes on the route to 1, namely, the nonclassical dihydrogen complexes [(iPr3P)2Rh(H)2(eta2-H2)x][B(ArF)4] (x = 1 or 2), have been observed spectroscopically. The high hydride content of 1 makes it a possible model for nanocluster colloidal Rh(0) catalysts that are used in olefin and arene hydrogenation.

Inorganic Coordination Polymers Based on Chalcocyanide Cluster Complexes

The paper reports results of experiments involving design of inorganic coordination polymers based on tetrahedral and octahedral chalcocyanide cluster complexes as building blocks. Various approaches to designing three‐dimensional, layered, and chain‐like structures are discussed. Structures of various types are described, and prospects of further studies in this field are outlined.