Synthesis and structures of new compounds based on tetrahedral rhenium chalcocyanide cluster anions [Re4Q4(CN)12]4− (Q = S or Se) and [Cu(bipy)2]2+ cations

The reactions of the rhenium chalcocyanide cluster salts K₄[Re₄Q₄(CN)₁₂]·6H₂O (Q = S or Se) with Cu²⁺ cations coordinated by the bidentate ligand 2,2′-bipyridyl (bipy) produced two new cluster compounds, [Cu(NH₃)(bipy)₂]₂[Re₄S₄(CN)₁₂]·bipy·3.25H₂O (1) and [{Cu(bipy)₂}₂Re₄Se₄(CN)₁₂]·bipy·8.5H₂O (2). The structures of these complexes were solved by X-ray diffraction. Compound 1 is ionic. Compound 2 is molecular. In the structures of both compounds, there are staking interactions between the {Cu(bipy)₂}²⁺ cationic moieties and the solvate 2,2′-bipyridyl molecules. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1875–1878, November, 2006.     

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.     

Synthesis,crystal structure,and thermal stability of ionic cluster compounds (phenH)4[Re4Q4(CN)12]·nH2O (Q = S,Se, n = 6; Q = Te,n = 10)

Three new salts of tetrahedral rhenium chalcocyanide cluster anions [Re₄Q₄(CN)₁₂]^4? (Q = S, Se, Te) and 1,10-phenanthroline-1-ium cations, (phenH)₄[Re₄S₄(CN)₁₂]·6H₂O (1), (phenH)₄[Re₄Se₄(CN)₁₂]·6H₂O (2), and (phenH)₄[Re₄Te₄(CN)₁₂]·10H₂O (3), have been synthesized by reactions of K₄[Re₄Q₄(CN)₁₂]·nH₂O with 1,10-phenanthroline in the presence of Nd³⁺ in an acidic aqueous medium (pH 4). 1 and 2 exhibit similar 2-D layered supramolecular architectures based on hydrogen bonds between water molecules, CN-groups of cluster anions, and phenH⁺ cations. The latter are involved in π–π and C–H?π stacking interactions, connecting the adjacent layers with each other. Complex 3 demonstrates a 3-D framework based on hydrogen bonds between water molecules and CN-groups, π–π and C–H?π interactions. Notably short O···Te contacts of 3.40 and 3.50 Å are found in the structure of 3. The thermal properties of 1–3 have been investigated by TG-DTG.     

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.     

New Method for the Synthesis of Octahedral Rhenium Chalcocyanide Cluster Complexes [{Re6(μ3-Q)8}(CN)6]4– (Q = S,Se, Te)

Russian Journal of Coordination Chemistry - A new method is proposed for the synthesis of the octahedral rhenium chalcocyanide cluster complexes [{Re6(μ3-Q)8}(CN)6]4– (Q = S, Se, Te)...     

New cyano-bridged complexes based on tetrahedral rhenium chalcocyanide clusters,Cu<Superscript>2+</Superscript> cations,and polydentate amines

Three new cyano-bridged compounds, viz., [{Cu(en)}{Cu(NH₃)(en)}Re₄Se₄(CN)₁₂]·{5H₂O (1), [{Cu(dien)}₂Re₄Te₄(CN)₁₂]·9H₂O (2), and [{Cu(trien)}₂Re₄Se₄(CN)₁₂]··5H₂O (3), were synthesized by the reactions of the tetrahedral rhenium chalcocyanide cluster complexes K₄[Re₄Q₄(CN)₁₂] ((Q = Se or Te) with copper(II) cations in aqueous solutions containing ethylenediamine (en), diethylenetriamine (dien), or triethylenetetraamine (trien), respectively. Complex 1 has a ladder-tubular-like polymeric structure, in which two infinite chains are linked to each other by Re-CN-Cu bridges, compound 2 has a polymeric chain structure, and compound 3 has a molecular structure. The structures of all complexes were established by X-ray diffraction analysis.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2040–2044, October, 2004.     

Specific interactions in metal salts and complexes with cluster boron anions BnH n2? (n = 6, 10, 12)

Specific interactions that appear in metal salts and complexes with cluster boron anions B _n H _n ²⁻ (n = 6, 10, 12) have been discussed. These interactions, as well as chemical bonds, involve vertices, edges, or faces of boron polyhedra. Specific interactions have a considerable effect on the structure of compounds, making a significant contribution to the formation of the unit cell and forming supramolecular assemblies. Compounds containing B _n H _n ²⁻ cluster anions shed new light onto the nature of specific interactions owing to their many-center character and great variety.     

Efficient Olefin Epoxidation by Robust Re4 Cluster‐Supported MnIII Complexes with Peracids: Evidence of Simultaneous Operation of Multiple Active Oxidant Species,MnVO,MnIVO,and MnIII?OOC(O)R

Two new tetranuclear chalcocyanide cluster complexes, [{Mn(saloph)H₂O}₄Re₄Q₄(CN)₁₂]?4 CH₃OH? 8 H₂O (saloph=N,N′‐o‐phenylenebis(salicylidenaminato), Q=Se ( 1 ‐Se), Te ( 2 ‐Te)), have been synthesized by the diffusion of a methanolic solution of [PPh₄]₄[Re₄Q₄(CN)₁₂] into a methanolic solution of [Mn(saloph)]⁺. The structure of 2 ‐Te has been determined by X‐ray crystallography. These rhenium cluster‐supported [Mn^III(saloph)] complexes have been found to efficiently catalyze a wide range of olefin epoxidations under mild experimental conditions in the presence of meta‐chloroperbenzoic acid (mCPBA). Olefin epoxidation by these catalysts is proposed to involve the multiple active oxidants Mn^V?O, Mn^IV?O, and Mn^III? OOC(O)R. Evidence in support of this interpretation has been derived from reactivity and Hammett studies, H₂¹⁸O‐exchange experiments, and the use of peroxyphenylacetic acid as a mechanistic probe. Moreover, it has been observed that the participation of Mn^V?O, Mn^IV?O, and Mn^III? OOC(O)R can be controlled by changing the substrate concentration. This mechanism provides the greatest congruity with related oxidation reactions that employ certain Mn complexes as catalysts.     

Reactions of Rhenium and Technetium Nitrido Complexes with ER3 Fragments (E = B,Ga, Al,C, P; R = H,Alkyl, Aryl)

Terminal ‘N^3—’ ligands in rhenium and technetium nitrido complexes are sufficiently nucleophilic to react with Lewis acids under formation of nitrido‐bridged compounds. The reactivity of the nucleophilic centre and the nature of the formed compounds are strongly dependent on the Lewis acid and the composition of the metal complex used. Air‐stable compounds with Re≡N‐ER₃ bridges are formed when ER₃ is BR₃ (R = H, Cl, Br, Ethyl, Phenyl, C₆F₅), BCl₂Ph, GaCl₃, CPh₃⁺, or PPh₃. The six‐co‐ordinate rhenium(V) complexes [ReNX₂(PMe₂Ph)₃] (X = Cl, Br), [ReN(X)(Et₂dtc)(PMe₂Ph)₂] (Et₂dtc^— = diethyldithiocarbamate) and [ReN(Et₂dtc)₂(PMe₂Ph)] have been proved to be excellent starting materials for this type of reactions, whereas the five‐co‐ordinate precursors [ReNCl₂(PPh₃)₂], [ReN(Et₂dtc)₂], [ReN{Ph₂P(S)NP(S)Ph₂}₂] or [ReNCl₄]^— only react with the most reactive Lewis bases of the examples mentioned above such as BCl₂Ph or B(C₆F₅)₃. The rhenium‐nitrido bond lengths remain almost unchanged by the adduct formation, whereas a significant decrease of the trans‐influence of the nitrido complexes has been observed as can be seen by a shortening of the corresponding bond lengths or dimerization of five‐co‐ordinate precursors. Electrophilic attack of the Lewis acid to a donor atom of the equatorial co‐ordination sphere of the rhenium complex results in the formation of ‘underco‐ordinate’ metal centres which resemble to di‐, tri or tetrameric units with asymmetric nitrido bridges between each two rhenium atoms. EPR spectroscopy is an excellent tool to reflect the formation of nitrido bridges at the paramagnetic (d¹) [ReNX₄]^— core (X = F, Cl, Br, NCS). The spectral parameters derived for the products of reactions of [ReNCl₄]^— with various boron compounds indicate an increase of the covalency of the equatorial Re‐L bonds as a consequence of the formation of a nitrido bridge. The tendency for the formation of nitrido bridges with Lewis acids is significantly lower for technetium compounds compared to their rhenium analogues. Only a few examples with BH₃ and BPhCl₂ have been established.     

Air‐Stable,Well‐Soluble AI2[Nb6Cl18] Cluster Compounds (AI = Organic Cation): A New Route for Preparation,Single‐Crystal Structures,Properties, and ESI‐Mass Spectra

Five niobium cluster compounds of the A^I₂[Nb₆Cl₁₈] type (A^I = organic cation: [nPr₄N]⁺, [nBu₄N]⁺, [BMIm]⁺, [Ph₄P]⁺, and [PPN]⁺) are obtained through treatment of [Nb₆Cl₁₄(H₂O)₄] · 4H₂O with excess of thionyl chloride in the presence of an organic chloride, A^ICl. Single‐crystal structure studies show that the compounds consist of discrete cations and cluster [Nb₆Cl₁₈]^2– anions. The cluster unit of the hydrated cluster starting material is oxidized by two electrons. Powder diffraction studies and NMR spectroscopic measurements show all compounds to crystallize without co‐crystallized solvent molecules. They are air and water stable. The solubility in organic solvents changes to a great extent on changing the type of cation. The ESI‐MS spectra of [nPr₄N]₂[Nb₆Cl₁₈] and [Ph₄P]₂[Nb₆Cl₁₈] show the pseudomolecular peak of the anionic cluster as well as additional signals, which involve simultaneously chloride mass loss and reduction processes.     

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 $ P\bar 1 triclinic space group with the unit cell parameters: a = 9.997(2) ?, b = 10.423(2) ?, c = 11.714(2) ?, α = 100.92(3)°, β = 111.87(3)°, γ = 98.05(3)°, V = 1082.1(4) ?³, Z = 1, d _calc = 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.     

Neue Rheniumkomplexe mit Trichalkogenido- und Tetrachalkogenido-Chelatliganden

New Rhenium Complexes Containing Trichalcogenido and Tetrachalcogenido Chelate Ligands The reactions of Cp*ReCl₄ with polychalcogenide salts such as Na₂S₄ or (NEt₄)₂Se₆ lead initially to the violet trichalcogenido chelate complexes Cp*ReCl₂(E₃) (E = S ( 3a ), Se ( 3b )) which, due to their functional chloro ligands, can be used as intermediates for further reactions. Upon hydrolysis in moist solvents or aminolysis with tert. butylamine 3a, b are converted into the tetrachalcogenido chelate complexes Cp*Re(O)(E₄) (E = S ( 4a ), Se ( 4b )) and Cp*Re(N^tBu)(E₄) (E = S ( 5a ), Se ( 5b )), respectively. X-Ray structure analyses were carried out for the three mononuclear cyclo-oligoselenido compounds 3b–5b . It appears that the size of the Se^2?_n chelate ring (n = 3 or 4) essentially depends on steric factors within the coordination sphere of rhenium.     

First example of the cluster ammine complex [Re6Se7Br(NH3)6]3+: synthesis and structure of the [Re6Se7Br(NH3)6][Re6Se7BrBr6]·12H2O salt

The reaction of Cs₃[Re₆Se₇BrBr₆] with aqueous ammonia afforded the octahedral rhenium ammine cluster complex cation [Re₆Se₇Br(NH₃)₆]³⁺. This cation crystallized as the [Re₆Se₇Br(NH₃)₆][Re₆Se₇BrBr₆]·12H₂O compound. The crystal structure of this compound was established. The presence of the NH₃ ligands in the coordination environment about the Re atom was confirmed by thermogravimetry, vibrational spectroscopy, and high-resolution mass spectrometry. The resulting compound is the first example of salts composed of the cluster cation and cluster anion possessing the same {Re₆Se₇Br} cluster core.     

New fac-tricarbonyl rhenium(I) semicarbazone complexes: synthesis,characterization, and biological evaluation

Expanding our previous work on salicylaldehyde semicarbazone metal complexes as prospective anti-trypanosomal agents, five new fac-Re^I(CO)₃-containing complexes with ligands of this semicarbazone series were synthesized and characterized. An atypical coordination mode of these potentially tridentate ligands through only the carbonylic oxygen and the azomethine nitrogen (the so-called N,O fashion) was demonstrated by IR spectroscopy and supported by theoretical calculations. Three of the compounds showed moderate in vitro anti-Trypanosoma cruzi activity and increased activity with respect to the corresponding free ligands. The brominated ligands, 5-bromo-2-hydroxybenzaldehyde semicarbazone (L2) and 5-bromo-2-hydroxy-3-methoxybenzaldehyde semicarbazone (L5), led to the most active rhenium(I) complexes. These compounds are among the few reported examples of rhenium complexes bearing in vitro activity against T. cruzi.     

Synthesis, structure, and thermal transformations of double complex salts [Au(C4H13N3)Cl][MCl6]· nH2O (M = Ir, Pt; n = 0–2)

Double complex salts [Au(C₄H₁₃N₃)Cl][MCl₆]·nH₂O (M = Ir, Pt; n = 0–2) were synthesized. According to X-ray diffraction data, compounds with n = 1.5 are isostructural; the crystal structure is composed of the complex cations [Au(dien)Cl]²⁺ (dien is diethylenetriamine), the complex anions [MCl₆]²⁻, and water molecules of crystallization. Thermolysis of the double complex salts under hydrogen and helium was studied. The formation of nonequilibrium solid solutions based on Ir in the Au-Ir system and based on Pt in the Au-Pt system was demonstrated. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 416–421, March, 2006.     

Unique (3,12)-Connected Inorganic Lanthanide Cluster Polymer Based on Octahedral Hexanuclear Europium Hydroxide Clusters and Sulfate Anions: Synthesis,Structure, and Luminescence

Abstract  

A (3,12)-connected 3D inorganic luminescent lanthanide hydroxide cluster polymer [Eu₆(μ₆-O) (μ₃-OH)₈(H₂O)₆(SO₄)₄] _n (1) has been hydrothermally synthesized and characterized. The structure can be considered to be constructed by linking 12-connected octahedral hexanuclear lanthanide oxido/hydroxide clusters with 3-connected inorganic SO₄ ²⁻ anions. Presently, it is the first 3D inorganic lanthanide cluster polymer based on octahedral hexanuclear lanthanide cluster with the highest connected binodal network topology. 1 displays red luminescent emission and exhibits the characteristic transitions of the Eu³⁺ ion with a decay lifetime of 196.25 μs in the solid state at room temperature.     

Coordination compounds of electron-deficient boron cluster anions BnH n2? (n = 6, 10, 12)

This survey concerns the coordination ability of B _n H _n ²⁻ (n = 6, 10, 12) boron cluster anions and their derivatives in complex formation. Boron cluster anions form four types of compounds: salts of organic cations and alkali-metal cations, including Cat₂B _n H _n , where specific interactions can be observed between a cation Cat and a boron cluster anion; salts of protonated anions CatB₆H₇ and CatB₁₀H₁₁, analogues of Cat[MB _n H _n ] complexes, where an extra hydrogen atom appears bound with the BBB face of a boron polyhedron and performs as a hard acceptor; metal complexes with outer-sphere boron cluster anions where specific ligand-ligand interactions may be observed between a boron cluster anion and an inner-sphere ligand; and true metal complexes with boron cluster anions that enter the inner coordination sphere. The last case characterizes closo-hydroborate anions as polydentate ligands whose denticity can vary widely under the effect of substituents or other ligands in the complex.     

Synthesis and X-ray crystal structures of new trirhenium nonachloride chalcogenide clusters

The acetone adduct of trirhenium nonachloride, Re₃Cl₉ (acet)₃, where acet=acetone, reacts in acetone solution at room temperature with tetrabutylammonium chalcogenides [N(C₄H₉)₄]₂E, where E=S, Se and Te, producing the tetrabutylammonium salts of the new cluster anions [Re₃ (μ₃-E) (μ₂-Cl)₃Cl₆]²−. In the crystallographically determined structures of these compounds, triangles of rhenium atoms are capped by single chalcogen atoms, giving anions of near C_3v symmetry. The compound where E=S is also formed in the reaction of Re₃Cl₉ with [N(C₄H₉)₄]₂ [MoS₄] by sulfide transfer.     

Synthesis,structure, and luminescence of rhenium(I) complexes with substituted bipyridines

Two new rhenium(I) complexes chelated by a substituted 2,2′-bipyridine with general formula Re(CO)₃LCl, where L?=?6?-(2″-methoxyphenyl)-2,2′-bipyridine (L₁ ) and 6?-(4″-diphenylaminophenyl)-2,2′-bipyridine (L₂ ), are synthesized and characterized by IR, NMR, and elemental analysis. Structure of 1 was determined by single-crystal X-ray crystallography, revealing that rhenium is six-coordinate octahedral. The electrochemical, photophysical, and thermal properties of the two rhenium(I) complexes were investigated. Electroluminescent devices were fabricated by doping 1 in polymer blend host of poly(vinylcarbazole) and 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole using simple solution spin-coating technique. The device exhibits a maximum current efficiency of 2.97?cd?A^?1 and peak brightness in excess of 2390?cd?m^?2.     

Cs10Tl6SiO4, Cs10Tl6GeO4, and Cs10Tl6SnO3 – First Oxotetrelate Thallides,Double Salts Containing “Hypoelectronic” [Tl6]6– Clusters

Cs₁₀Tl₆TtO₄ (Tt = Si, Ge) and Cs₁₀Tl₆SnO₃ were synthesized by the reaction of appropriate starting materials at 623–673 K, followed by fast cooling or quenching to room temperature, in arc‐welded tantalum ampoules. According to single‐crystal X‐ray analyses, the compounds crystallize in new structure types (Cs₁₀Tl₆TtO₄ (Tt = Si, Ge), P2₁/c and Cs₁₀Tl₆SnO₃, Pnma), consisting of [Tl₆]^6– clusters, which can be characterized as distorted octahedra compressed along one of the fourfold axes of an originally unperturbed octahedron, and [SiO₄]^4–, [GeO₄]^4– or [SnO₃]^4– anions. The oxotetrelate thallides can be regarded as “double salts”, which consist of Cs₆Tl₆ on one side and respective oxosilicates, ‐germanates and ‐stannates on the other, showing almost not any direct interaction between the two anionic moieties, as might be expressed e.g. by the formula [Cs₆Tl₆][Cs₄SiO₄]. In contrast to the silicon and germanium compounds, where the oxidation state of the tetrel atom is unambiguously 4+, for the threefold coordinated tin atom in Cs₁₀Tl₆SnO₃ an oxidation state of 2+ has to be assumed. Thus, the latter reveal further evidence that the so called “hypoelectronic” [Tl₆]^6– cluster does not require additional electrons and is intrinsically stable. The distortion of [Tl₆]^6– can be understood in terms of the Jahn–Teller theorem. According to magnetic measurements all title compounds are diamagnetic.