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It is known that niobium practically does not form cluster chalcogenide compounds of the {M 6 (μ 3 -Q 8 )} type, which are widespread in the chemistry of group 6 and 7 metals. This work reports the preparation of a series of polymeric and discrete niobium-containing heterometallic clusters based on the {Re 5 Nb(μ 3 -S 8 )} and {Re 5 Nb(μ 3 -Se 8 )} cores. The compounds were prepared by the high-temperature reaction between rhenium and niobium dichalcogenides in a KCN melt. The 1D polymers K 5 [Re 5 NbQ 8 (CN) 5 ] (Q = S or Se), which were formed as a result of the reaction, crystallize in the structural type of K 6 [Mo 6 Se 8 (CN) 5 ], similar to the previously reported heterometallic clusters K 6 [Re 6- x Mo x Q 8 (CN) 5 ] ( x = 2-3). The polymers were solubilized to form discrete anionic clusters [Re 5 NbQ 8 (CN) 6 ] 4- . The structure and properties of the new clusters were investigated using a combination of X-ray diffraction analysis, UV/vis spectroscopy, high-resolution electrospray mass spectrometry, cyclic voltammetry, and DFT calculations. Among other features, the compounds showed high electrochemical activity, being able to form three redox states in solution with reversible transitions. It was found that redox potentials of the isoelectronic octahedral clusters demonstrate a strong cathodic shift in the sequence [Re 5 OsSe 8 (CN) 6 ] 3- > [Re 6 Se 8 (CN) 6 ] 4- > [Re 5 MoSe 8 (CN) 6 ] 5- > [Re 5 NbSe 8 (CN) 6 ] 6- , illustrating the effect of systematic changes in the composition of octahedral cluster cores on their properties.

A series of new cluster compounds with {Re 4 Mo 2 S 8 } and {Re 3 Mo 3 S 8 } cores has been obtained and investigated. The clusters with different Re/Mo ratios were isolated as individual compounds, which made it possible to study their spectroscopic and electrochemical properties. The geometry of the new clusters was studied using a combination of X-ray diffraction analysis, XAS and quantum chemical DFT calculations. It was shown that the properties of the new clusters, such as the number and position of electrochemical transitions, electronic structure and change in geometry with a change in charge, are similar to the properties of clusters based on the {Re 4 Mo 2 Se 8 } and {Re 3 Mo 3 Se 8 } cores described earlier.

This work reports the preparation of new quaternary sulfides Cs 2 Ln 3 CuS 8 (Ln = La-Nd, Sm-Tb), their original crystal and electronic structures, and their magnetic properties. The sulfides were prepared using a reactive flux method from mixtures of Ln 2 S 3 (EuS), Cs 2 S 6 , Cu 2 S, and S. They crystallize in a new type of structure ( C 2/ m space group) and exhibit a layer-like crystal structure, which is a hybrid of those of the ACe 2 CuS 6 series (A = Cs, K) and that of K 2 CeCu 2 S 4 . The values of the optical band gap calculated by the Kubelka-Munk equation are in the range of 1.2-2.62 eV depending on the nature of the Ln ion. The Cs 2 Gd 3 CuS 8 compound displays relatively great magnetic refrigerating properties at cryogenic temperature with the mass entropy change (-Δ S M ) reaching 19.5 J kg -1 K -1 at 3.5 K for Δ H = 5 T.

We have obtained three new rhenium(IV) chalcobromides belonging to the homologous series {Re 4 S 4 }Br 8 (TeBr 2 ) n ( n = 0, 3, 4): a molecular complex {Re 4 S 4 }Br 8 (TeBr 2 ) 4 ( 1 ), a dimeric complex [{Re 4 S 4 }(TeBr 2 ) 3 Br 7 (μ-Br)] 2 ( 2 ), and a two-dimensional (2D) polymeric compound {Re 4 S 4 }Br 8 ( 3 ). Compound 1 is isotypic to the already known {Re 4 Te 4 }(TeBr 2 ) 4 Br 8 , while 2 and 3 exhibit a new type of binding of tetrahedral clusters via μ-Br bridges. Compounds were characterized by X-ray single-crystal diffraction, X-ray powder diffraction, and thermal and elemental analyses. In compound 2 , two tetrahedral cluster cores {Re 4 S 4 } 8+ are linked together forming a dimer through two Re-μ-Br-Re bridges. Calculations of the electron localization function (ELF) showed that there is no covalent interaction between rhenium atoms of neighboring clusters. In compound 3 , each rhenium atom of the {Re 4 S 4 } 8+ core is coordinated by three Br ligands: one terminal Br and two bridging μ-Br ligands. As a result, eight bridging bromine atoms link {Re 4 S 4 } 8+ cluster cores into goffered layers. {Re 4 S 4 }Br 8 is the new stable rhenium(IV) thiobromide, the first discovered in the Re-S-Br system, along with the already known octahedral rhenium(III) thiobromides Re 6 S 4+ x Br 10-2 x ( x = 0-4).

The heterometallic cluster-based compound K 5 [Re 5 MoSe 8 (CN) 6 ] was obtained by high-temperature reaction from a mixture of ReSe 2 and MoSe 2 in molten potassium cyanide. The redox behavior of the [Re 5 MoSe 8 (CN) 6 ] 5- cluster anion was studied by cyclic voltammetry in aqueous and organic media showing two reversible one-electron-redox transitions with E 1/2 of -0.462 and 0.357 V versus Ag/AgCl in CH 3 CN. Aqueous media potentials were found to be noticeably shifted to higher values because of solvation. Chemically accessible potentials allowed us to structurally isolate and characterize the [Re 5 MoSe 8 (CN) 6 ] n ( n = 3-, 4-, and 5-) cluster complex in several charge states with corresponding cluster skeletal electron (CSE) numbers ranging from 24 to 22. The electronic absorption of the [Re 5 MoSe 8 (CN) 6 ] n cluster complex varies significantly upon a change of the CSE number, especially in the visible and near-IR regions. The local cluster core distortion upon electron removal was confirmed by density functional theory calculation, while the overall geometry of the cluster anion remained practically unaltered.

The reaction of the K 4 [{Re 6 S i 8 }(OH) a 6 ]·8H 2 O rhenium cluster salt with pyrazine (Pz) in aqueous solutions of alkaline or alkaline earth salts at 4 °C or at room temperature leads to apical ligand exchange and to the formation of five new compounds: [ trans- {Re 6 S i 8 }(Pz) a 2 (OH) a 2 (H 2 O) a 2 ] ( 1 ), [ cis- {Re 6 S i 8 }(Pz) a 2 (OH) a 2 (H 2 O) a 2 ] ( 2 ), (NO 3 )[ cis- {Re 6 S i 8 }(Pz) a 2 (OH) a (H 2 O) a 3 ](Pz)·3H 2 O ( 3 ), [Mg(H 2 O) 6 ] 0.5 [ cis- {Re 6 S i 8 }(Pz) a 2 (OH) a 3 (H 2 O) a ]·8.5H 2 O ( 4 ), and K[ cis -{Re 6 S i 8 }(Pz) a 2 (OH) a 3 (H 2 O) a ]·8H 2 O ( 5 ). Their crystal structures are built up from trans - or cis -[{Re 6 S i 8 }(Pz) a 2 (OH) a 4-x (H 2 O) a x ] x-2 cluster units. The cohesions of the 3D supramolecular frameworks are based on stacking and H bonding, as well as on H 3 O 2- bridges in the cases of ( 1 ), ( 2 ), ( 4 ), and ( 5 ) compounds, while ( 3 ) is built from stacking and H bonding only. This evidences that the nature of the synthons governing the cluster unit assembly is dependent on the hydration rate of the unit.

Influence of the metal core composition and geometry on the structure, spectroscopic properties and redox potentials was investigated for the first time for heterometallic (Re/Mo) 6 octahedral clusters. The discrete anionic clusters [Re 6-x Mo x Se 8 (CN) 6 ] n- (x=2, 3; n=4, 5) were obtained as individual salts. Their isomeric composition and bond-length distribution were inspected using a combination of single-crystal X-ray structure analysis, NMR, EXAFS, and DFT calculations., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Among the great amount of known lanthanide nanoparticles, reports devoted to chalcogenide ones are deficient. The properties of such nanoparticles remain almost unknown due to the lack of simple and proper synthetic methods avoiding hydrolysis and allowing preparation of oxygen-free lanthanide nanoparticles. A liquid exfoliation method was used to select the optimum strategy for the preparation of quaternary lanthanide sulfide nanoparticles. Bulk KLn 2 CuS 6 (Ln = La-Sm) materials were obtained via a reactive flux method. The crystal structures of three new members of the KLn 2 CuS 6 series were determined for Pr, Nd, and Sm as well as for known KLa 2 CuS 6 . KLn 2 CuS 6 (Ln = La, Pr, Nd) compounds crystallize in the monoclinic C2 /c space group, whereas KSm 2 CuS 6 crystallizes in the orthorhombic Fddd space group. The analysis of their electronic structures confirms that the main bonding interactions occur within the anionic {Ln 2 CuS 6 } - layers. Due to their layered structure, exfoliation of these compounds is possible using ultrasonic treatment in appropriate solvents with the formation of colloidal solutions. Colloidal particles show a plate-like morphology with a lateral size of 100-200 nm and a thickness of 2-10 nm. Highly negative or positive charges found in isopropanol and acetonitrile dispersions, respectively, are associated with high stability and concentration of the dispersions.

Water-soluble salts of anionic [Re 6 Q 8 (CN) 6 ] 4- (Q=S, Se, Te) chalcogenide octahedral rhenium clusters react with γ-cyclodextrin (γ-CD) producing a new type of inclusion compounds. Crystal structures determined through single-crystal X-ray diffraction analysis revealed supramolecular host-guest assemblies resulting from close encapsulations of the octahedral cluster within two γ-CDs. Interestingly, nature of the inner Q ligands influences strongly the host-guest conformation. The cluster [Re 6 S 8 (CN) 6 ] 4- interacts preferentially with the primary faces of the γ-CD while the bulkier clusters [Re 6 Se 8 (CN) 6 ] 4- and [Re 6 Te 8 (CN) 6 ] 4- exhibit specific interactions with the secondary faces of the cyclic host. Furthermore, analysis of the crystal packing reveals additional supramolecular interactions that lead to 2D infinite arrangements with [Re 6 S 8 (CN) 6 ] 4- or to 1D "bamboo-like" columns with [Re 6 Se 8 (CN) 6 ] 4- and [Re 6 Te 8 (CN) 6 ] 4- species. Solution studies, using multinuclear NMR methods, ESI-MS and Isothermal titration calorimetry (ITC) corroborates nicely the solid-state investigations showing that supramolecular pre-organization is retained in aqueous solution even in diluted conditions. Furthermore, ITC analysis showed that host-guest stability increases significantly ongoing from S to Te. At last, we report herein that deep inclusion alters significantly the intrinsic physical-chemical properties of the octahedral clusters, allowing redox tuning and near IR luminescence enhancement., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The search for new multifunctional materials displaying proton-conducting properties is of paramount necessity for the development of electrochromic devices and supercapacitors as well as for energy conversion and storage. In the present study, proton conductivity is reported for the first time in three molybdenum cluster-based materials: (H) 4 [Mo 6 Br 6 S 2 (OH) 6 ]-12H 2 O and (H) 2 [Mo 6 X 8 (OH) 6 ]-12H 2 O (X = Cl, Br). We show that the self-assembling of the luminescent [Mo 6 L 8 i (OH) 6 a ] 2-/4- cluster units leads to both luminescence and proton conductivity (σ = 1.4 × 10 -4 S·cm -1 in (H) 2 [Mo 6 Cl 8 (OH) 6 ]-12H 2 O under wet conditions) in the three materials. The latter property results from the strong hydrogen-bond network that develops between the clusters and the water molecules and is magnified by the presence of protons that are statistically shared by apical hydroxyl groups between adjacent clusters. Their role in the proton conduction is highlighted at the molecular scale by ab initio molecular dynamics simulations that demonstrate that concerted proton transfers through the hydrogen-bond network are possible. Furthermore, thermogravimetric analysis also shows the ability of the compounds to accommodate more or less water molecules, which highlights that vehicular (or diffusion) transport probably occurs within the materials. An infrared fingerprint of the mobile protons is finally proposed based on both theoretical and experimental proofs. The present study relies on a synergic computational/experimental approach that can be extended to other proton-conducting materials. It thus paves the way to the design and understanding of new multifunctional proton-conducting materials displaying original and exciting properties.

Providing several functionalities to a single material is an emerging challenge with many industrial prospects in materials sciences. Self-assembled organic-inorganic hybrid materials endowed with emission properties are part of these new materials. While the inorganic moieties provide emissivity, the organic part confers nanostructuration and processability. Here we describe how columnar arrangements can be obtained by assembling, via electrostatic interactions, isometric anionic inorganic nanoemitters, namely [Re6Se8(CN)6]4-, with imidazolium counter cations bearing triphenylene units. The resulting hybrids combine the emission of both components and energy transfer has been evidenced between both entities. Hole charge mobilities of the hybrid organic-inorganic columnar mesophases were also evaluated by the space charge limited current (SCLC) method.

Cluster compounds based on a new {Re 3 Mo 3 Se 8 } n core were obtained and studied. The polymeric solid K 6 [Re 3 Mo 3 Se 8 (CN) 4 (CN) 2/2 ] (1) containing 24 cluster valence electrons (CVE) was isolated as a result of high-temperature reaction. Water-soluble salts K 5 [Re 3 Mo 3 Se 8 (CN) 6 ]·11H 2 O (2) and Cs 5 [Re 3 Mo 3 Se 8 (CN) 6 ]·H 2 O (3) were prepared from compound 1. Crystal structures of the diamagnetic compounds 2 and 3 contain a cluster anion [Re 3 Mo 3 Se 8 (CN) 6 ] 5- with a 22-electronic core {Re 3 Mo 3 Se 8 } + . Metathesis reaction followed by recrystallization from CH 3 CN yielded paramagnetic salt (Ph 4 P) 4 [Re 3 Mo 3 Se 8 (CN) 6 ]·2CH 3 CN (4) containing the {Re 3 Mo 3 Se 8 } 2+ core with 21 CVE. Cyclic voltammetry of the solution of 4 displayed three quasi-reversible waves with E 1/2 = -0.325, -0.818 and -1.410 V vs. Ag/AgCl electrode indicating the presence of [Re 3 Mo 3 Se 8 (CN) 6 ] 4-/5-/6-/7- transitions. Electronic structure calculations showed that both mer- and fac-isomers of [Re 3 Mo 3 Se 8 (CN) 6 ] n- clusters undergo great distortion when the number of CVE decreases.

Herein, two new octahedral molybdenum cyanide cluster compounds, namely [{Ni(NH 3 ) 6 } 4 {Ni 2 (NH 3 ) 8 } 1 ][Mo 6 Br 6 Q 2 (CN) 6 ] 3 ·12H 2 O, Q = S (1) and Se (2), have been synthesized as single crystals by slow diffusion of a solution of nickel chloride into aqueous ammonia solutions of a K 2 Cs 2 [Mo 6 Br 6 Q 2 (CN) 6 ] molybdenum cyanide cluster-based compound. Both 1 and 2 were structurally characterized by single-crystal X-ray diffraction. They are isostructural and crystallize in the cubic system (Im3[combining macron]m (no. 229); Z = 2, a = 18.147(1) Å, and V = 5976(1) Å 3 and a = 18.188(2) Å and V = 6016(2) Å 3 for 1 and 2, respectively). 1 and 2 are based on the association of [Mo 6 Br i 6 Q i 2 (CN) a 6 ] 4- (Q = S, Se) cluster anions with Ni 2+ dimer-based cubic [Ni 2 (NH 3 ) 8 ] 4+ and octahedral [Ni(NH 3 ) 6 ] 2+ cations. The structure is based on 2-fold interpenetrated [{Ni(NH 3 ) 6 } 4 {Ni 2 (NH 3 ) 8 } 1 ][Mo 6 Br 6 Q 2 (CN) 6 ] 3 frameworks related to each other by [½, ½, ½] translation. The unit cell is based on a body-centered cubic framework of cubic [Ni 2 (NH 3 ) 8 ] 4+ . The [Mo 6 Br i 6 Q i 2 (CN) a 6 ] 4- (Q = S, Se) cluster units are located in the middle of the edges and at the center of the faces of the cell. The [{Ni(NH 3 ) 6 }] 2+ cations are located at the center of the cubes of the a/2 edge. The dimers [Ni 2 (NH 3 ) 8 ] 4+ are stabilized by hydrogen bonds between the cyanide ligands of the cluster unit and the hydrogen atoms of the ammonia molecules. Both compounds exhibit a weak antiferromagnetic coupling within the [Ni 2 (NH 3 ) 8 ] 4+ dimer entities at low temperatures together with a paramagnetic behavior originating from the cations of the octahedral [{Ni(NH 3 ) 6 }] 2+ complexes.

New luminescent poly(methylmethacrylate) (PMMA) nanocomposites with high content of different hexanuclear octahedral cluster building blocks, namely [Mo6I8(C2F5COO6)](2-), [Re6Se8(CN)6](4-) and [W6Cl14](2-) have been prepared by free-radical polymerisation. To do so, cluster complexes bearing a polymerisable ammonium counter-cation have been synthesised. In this way, we demonstrate that ionic assembling is a powerful tool to functionalise easily any type of anionic cluster units to be introduced in a PMMA organic matrix. All samples remain homogeneous, stable during several months, and retain the luminescence properties of the cluster precursor.

Reactive changes of astrocytes were studied in forebrain nucleus accumbens in rats (n = 12) after global cerebral ischemia induced by bilateral occlusion of both common carotid arteries, which is a frequently used model to assess the effectiveness of pharmacological agents that have anti-ischemic and neuroprotective properties. Under these conditions, the nucleus accumbens was in the area of partial ischemia. Morphometric study of nucleus accumbens was performed in three groups of rats (4 animals in each group) after ligation of both common carotid arteries, after a sham operation and in healthy animals. Astrocytes were demonstrated in serial sections using the reaction to glial fibrillary acidic protein counterstained with hematoxylin. 7 days after the surgery, in each animal the number of astrocytes was counted in the sections in 7 successiive squares of 0.01 mm2 each, the distance between their bodies and the capillary wall was measured within the circle of 20 μm radius, the cell body area and the length of their main processes were determined. It is found that astrocytes in the nucleus accumbens in the model of bilateral occlusion of the common carotid arteries for 7 days experienced a partial state of ischemia. Their reactive changes were manifested by the signs of the cytotoxic edema, damaging intermediate filament proteins in their bodies, processes and in the perivascular glial membranes. The concentration of the astrocyte cell bodies near blood capillaries is the adaptation mechanism and is a condition for the survival of cells under the restriction of blood flow in the brain.

We report the direct facile high-temperature synthesis and investigation of heterometallic rhenium-molybdenum cluster K6[Re3Mo3S8(CN)4(CN)2/2] (1) with a new {Re3Mo3S8} core. Dissolution of polymeric compound 1 resulted in subsequent oxidation and formation of stable 23e paramagnetic anionic cluster complex [Re3Mo3S8(CN)6](6-).

Metal atom clusters constitute very promising candidates as luminophores for applications in biotechnology because they are nanosized entities offering robust luminescence in the near-infrared field (NIR). However, they cannot be used as prepared for biological applications because of potential toxic effects and quenching of the clusters' luminescence in aqueous media, and they therefore need to be dispersed in a biocompatible matrix. We describe herein the encapsulation of octahedral rhenium clusters, denoted as A(4)[Re(6)Q(8)L(6)] (A = Cs or K, Q = S or Se, and L = OH or CN), in silica nanoparticles by a water-in-oil microemulsion process, paying particular attention to the clusters' stability. The obtained A(4)[Re(6)Q(8)L(6)]@SiO(2) nanoparticles are 30 nm in size with good monodispersity and a perfectly spherical shape, as shown by scanning electron microscopy (SEM). The presence of cluster units inside the silica matrix was evidenced by scanning transmission electron microscopy in annular dark-field mode (ADF-STEM). From the point of view of their optical properties, the A(4)[Re(6)Q(8)L(6)]@SiO(2) nanoparticles show red and NIR emission under UV excitation, even when dispersed in water. The evolution of the structural and luminescence properties of clusters before and after encapsulation was followed by Raman and photoluminescence spectroscopy.

X-Ray studies and (1)H NMR measurements for novel cyano-bridged polymers [(H){Ln(H(2)O)(4)}{Re(6)S(8)(CN)(6)}]*2H(2)O (Ln = Yb, Lu) reveal temperature dependence of proton localization: acid protons are trapped between nitrogen atoms at low temperatures, but can be transferred to the water sublattice at higher temperatures; this transfer resulted in intermolecular proton exchange.

The conversions of hexahydroxo rhenium cluster complexes [Re6Q8(OH)6]4- (Q=S, Se) in aqueous solutions in a wide pH range were investigated by chemical methods and spectroscopic measurements. Dependences of the spectroscopic and excited-state properties of the solutions on pH have been studied in detail. It has been found that a pH decrease of aqueous solutions of the potassium salts K4[Re6Q8(OH)6].8H2O (Q=S, Se) results in the formation of aquahydroxo and hexaaqua cluster complexes with the general formula [Re6Q8(H2O)n(OH)6-n]n-4 that could be considered as a result of the protonation of the terminal OH- ligands in the hexahydroxo complexes. The compounds K2[Re6S8(H2O)2(OH)4].2H2O (1), [Re6S8(H2O)4(OH)2].12H2O (2), [Re6S8(H2O)6][Re6S6Br8].10H2O (3), and [Re6Se8(H2O)4(OH)2] (4) have been isolated and characterized by X-ray single-crystal diffraction and elemental analyses and infrared (IR) spectroscopy. In crystal structures of the aquahydroxo complexes, the cluster units are connected to each other by an extensive system of very strong hydrogen bonds between terminal ligands.

The compounds [Ni(en)(3)](2)[Re(6)Te(8)(CN)(6)].10H(2)O (1), [Ni(NH(3))(4)(en)](2)[Re(6)Te(8)(CN)(6)].2H(2)O (2), [Ni(NH(3))(2)(en)(2)][(Ni(en)(2))(3)(Re(4)Te(4)(CN)(12))(2)].38H(2)O (3), [Co(NH(3))(2)(en)(2)](2)[(Co(en)(2))Re(6)Te(8)(CN)(6)]Cl(2).H(2)O (4),and [(Zn(H(2)O)(en)(2))(Zn(en)(2))Re(6)Te(8)(CN)(6)].3H(2)O (5) (en = ethylenediamine) have been synthesized and characterized. Compounds 1, 4, and 5 have been synthesized by the diffusion of an aqueous (for 1 and 5) or an ammonia (for 4) solution of Cs(4)[Re(6)Te(8)(CN)(6)].2H(2)O into a glycerol solution of NiCl(2).6H(2)O (for 1), CoCl(2).6H(2)O (for 4), or ZnCl(2) (for 5). Compounds 2 and 3 have been synthesized by the reaction of an aqueous solution of Cs(4)[Re(6)Te(8)(CN)(6)].2H(2)O (for 2) or K(4)[Re(4)Te(4)(CN)(12)].5H(2)O (for 3) with an ammonia solution of Ni(en)(2)Cl(2). Compounds 1 and 2 are ionic whereas compounds 4 and 5 are one-dimensional polymers. Compound 3, a two-dimensional polymer, possesses hexagonal shaped channels of approximate diameter 10-12 A. Because the framework of compound 3 is robust, it is an attractive host for guest molecules of appropriate size and shape. The potential "guest" volume is about 37% of the unit cell volume.

Two new anions [Nb(6)F(i)(6)X(i)(6)(NCS)(a)(6)](4-)(X = Br, I) based on octahedral niobium clusters with edge-bridging F ligands have been prepared by reaction of Cs(3)Nb(6)F(6)Br(12) and Cs(4)Nb(6)F(8.5)I(9.5) with aqueous solution of KSCN. The anions were isolated as (Et(4)N)(6)[Nb(6)F(6)Br(6)(NCS)(6)]Br(2) (1)and Cs(1.6)K(2.4)[Nb(6)F(6)I(6)(NCS)(6)] (2) salts.

The syntheses, crystal structures determined by single-crystal X-ray diffraction, and characterizations of new Mo(6) cluster chalcobromides and cyano-substituted compounds with 24 valence electrons per Mo(6) cluster (VEC = 24), are presented in this work. The structures of Cs(4)Mo(6)Br(12)S(2) and Cs(4)Mo(6)Br(12)Se(2) prepared by solid state routes are based on the novel [(Mo(6)Br(i)(6)Y(i)(2))Br(a)(6)](4)(-) (Y = S, Se) discrete units in which two chalcogen and six bromine ligands randomly occupy the inner positions, while the six apical ones are fully occupied by bromine atoms. The interaction of these two compounds with aqueous KCN solution results in apical ligand exchange giving the two first Mo(6) cyano-chalcohalides: Cs(0.4)K(0.6)(Et(4)N)(11)[(Mo(6)Br(6)S(2))(CN)(6)](3).16H(2)O and Cs(0.4)K(0.6)(Et(4)N)(11)[(Mo(6)Br(6)Se(2))(CN)(6)](3).16H(2)O. Their crystal structures, built from the original [(Mo(6)Br(i)(6)Y(i)(2))(CN)(a)(6)](4)(-) discrete units, will be compared to those of the two solid state precursors and other previously reported Mo(6) cluster compounds. Their redox properties and (77)Se NMR characterizations will be presented. Crystal data: Cs(4)Mo(6)Br(12)S(2), orthorhombic, Pbca (No. 61), a = 11.511(5) A, b = 18.772(5) A, c = 28.381 A (5), Z = 8; Cs(4)Mo(6)Br(12)Se(2), Pbca (No. 61), a = 11.6237(1) A, b = 18.9447(1) A, c = 28.4874(1) A, Z = 8; Cs(0.4)K(0.6)(Et(4)N)(11)[(Mo(6)Br(6)S(2))(CN)(6)](3).16H(2)O, Pm-3m (No. 221), a = 17.1969(4) A, Z = 1; Cs(0.4)K(0.6)(Et(4)N)(11)[(Mo(6)Br(6)Se(2))(CN)(6)](3).16H(2)O, Pm-3m (No. 221), a = 17.235(5) A, Z = 1.

Dehydration process in recently synthesized porous inorganic salts formed by large cluster anions [Re6X8(CN)6]4- (X= S, Se), transition metal cations and water molecules has been investigated. Desolvation process of the complex Co(DMF)6[Mo6Br8(NCS)6], where DMF dimethylformamide. has been studied. CoK, MoK and ReL3 XAFS measurements of these new complicated compounds before and after annealing in vacuum at temperature up to 250 degrees C were performed. Changes of electronic and spatial structure of these compounds under the heating process have been established and adequate structural models of the amorphous compounds obtained are suggested and discussed.

The synthesis of new molybdenum cluster selenocyanide anionic complexes [Mo6Se8(CN)6]7- and [Mo6Se8(CN)6]6- is reported. The [Mo6Se8(CN)6]7- ion was obtained by excision of the cluster core [Mo6Se8] from a Chevrel phase in the reaction of Mo6Se8 with KCN at 650 degrees C; the [Mo6Se8(CN)6]6- ion is formed by oxidation of [Mo6Se8(CN)6]7-. New cluster salts K7[Mo6Se8(CN)6] x 8H2O (1) and (Me4N)4K2[Mo6Se8(CN)6] x 10H2O (2) were isolated and their crystal structures were solved. Compound 1 crystallizes in the cubic space group Fm3m (a=15.552(2) A, Z=4, V=3761.5(8) A3), compound 2 crystallizes in the triclinic space group P1 (a=11.706(2), b=11.749(2), c=12.459(2) A, alpha=72.25(1), beta=77.51(1), gamma=63.04(1), Z=1, V=1448.5(4) A3). Compound 1 is paramagnetic due to an availability of 21 electrons per Mo6 cluster; cyclic voltammetry reveals a quasi-reversible transition [Mo6Se8(CN)6]7- <--> [Mo6Se8(CN)6]6-, E1/2=0.63 V.