Rearrangement of the {Mo6S8}cluster fragment to {Mo4S4} and a New {Mo6S6} Cluster Nucleus: Crystal Structure of K6[Mo4S4(CN)12]·10H2O and (18-Crown-6K)8[Mo6S6(CN)16]·17.5H2O

Two new compounds containing molybdenum thiocyanide cluster anions, K₆[Mo₄S₄(CN)₁₂]·10H₂O (1) and (18-crown-6K)₈[Mo₆S₆(CN)₁₆]·17.5H₂O (2), were synthesized and investigated by X-ray structure analysis. Crystal data: a=11.8430(17), b=11.8430(17), c=35.170(7) , V=4932.8(14) ³, space group I4₁/a, Z=4, d_calc=1.563 g/cm³ for 1; a=28.7513(5), b=18.4190(3), c=20.7586(4) , =118.5982(7)°, V=9651.9(3) ³, space group C2/m, Z=4, d_calc =1.563 g/cm³ for 2. The [Mo₄S₄(CN)₁₂]^6- cluster anion in 1 has an ordinary structure typical of cubane transition metal complexes. In the structure of the [Mo₆S₆(CN)₁₆]^8- anion of 2, two crystallographically independent molybdenum atoms form a Mo₆ metallocluster, represented as two edge-sharing tetrahedra.     

Cyanide Complexes Based on {Mo6I8}4+ and {W6I8}4+ Cluster Cores

Compounds based on new cyanide cluster anions [{Mo₆I₈}(CN)₆]^2–, trans-[{Mo₆I₈}(CN)₄(MeO)₂]^2– and trans-[{W₆I₈}(CN)₂(MeO)₄]²⁻ were synthesized using mechanochemical or solvothermal synthesis. The crystal and electronic structures as well as spectroscopic properties of the anions were investigated. It was found that the new compounds exhibit red luminescence upon excitation by UV light in the solid state and solutions, as other cluster complexes based on {Mo₆I₈}⁴⁺ and {W₆I₈}⁴⁺ cores do. The compounds can be recrystallized from aqueous methanol solutions; besides this, it was shown using NMR and UV-Vis spectroscopy that anions did not undergo hydrolysis in the solutions for a long time. These facts indicate that hydrolytic stabilization of {Mo₆I₈} and {W₆I₈} cluster cores can be achieved by coordination of cyanide ligands.     

Synthesis,structure, and properties of compounds containing both octahedral rhenium cluster cations and anions

The compound [{Re₆S₈}(3,5-Me₂pzH)₆]₂[{Re₆S₈}Br₆]?9H₂O?4EtOH containing a cluster cation and a cluster anion in a 2: 1 ratio was synthesized by mixing an ethanol solution of the rhenium cluster complex [{Re₆S₈}(3,5-Me₂pzH)₆]Br₂?2(3,5-Me₂pzH) (pzH is pyrazole) with an aqueous solution of Cs₄[{Re₆S₈}Br₆]?2H₂O. The resulting compound was characterized by a combination of physicochemical methods. In particular, luminescence properties were studied and compared with those of the parent cluster complexes. A crystal suitable for single-crystal X-ray diffraction was obtained by layering these solutions. According to single-crystal X-ray diffraction analysis, this compound is composed of a cluster cation and a cluster anion (in a ratio of 1: 1) and also of Zundel cations (H₅O₂ ⁺) and solvate water molecules and is described by the formula (H₅O₂)₂[{Re₆S₈}(3,5-Me₂pzH)₆][{Re₆S₈}Br₆]?4H₂O.     

Highly luminescent complexes [Mo6X8(n-C3F7COO)6]2- (X=Br, I)

New complexes (Bu(4)N)(2)[Mo(6)X(8)(n-C(3)F(7)COO)(6)] (X = Br, I) display extraordinarily bright long-lived red phosphorescence both in solution and solid phases, with the highest emission quantum yields and the longest emission lifetimes among hexanuclear metal cluster complexes of Mo, W and Re, hitherto reported.     

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]. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1614–1619, August, 2008.     

Red‐NIR Luminescent Hybrid Poly(methyl methacrylate) Containing Covalently Linked Octahedral Rhenium Metallic Clusters

The embedding of functional inorganic entities into polymer matrices has become an intense field of investigation in which the main challenges are to keep the added value of the inorganic entities while preventing their self‐aggregation within the organic matrix. We present a simple way to obtain a homogeneous highly red‐NIR luminescent hybrid copolymer that contains covalently bonded nanometric‐sized {Re₆} octahedral clusters. The [Re₆Seⁱ₈(OH)^a₆]^4? cluster complexes are primarily functionalized in two steps with tert‐butylpyridine (TBP) and methacrylic acid (MAC) to give neutral [Re₆Se₈(TBP)₄(MAC)₂] building blocks that are copolymerized with methyl methacrylate (MMA) either in solution or in bulk in the presence of azobisisobutyronitrile as an initiator. Several samples containing 0, 0.025, 0.05, and 0.1 wt % of functionalized {Re₆} clusters were prepared. As the {Re₆} cluster/MMA ratio is very low, the obtained copolymers keep the entire processability of pure poly(methyl methacrylate) (PMMA), as demonstrated by differential scanning calorimetry and thermogravimetric analysis. Voltammetric and luminescence studies also indicate that the intrinsic properties of the clusters are preserved within the polymer matrix. All the samples show a bright (emission quantum yield=0.07), broad, and structureless emission band, which extends from λ=600 nm to more than λ=950 nm, with the maximum wavelength centered around λ_em=710 nm either in solution or in the solid state. Moreover, the high stability of the incorporated inorganic phosphors prevents the material from photobleaching, and thus the luminescence properties are kept entirely even after nine months of ageing.     

Novel Three-Dimensional Coordination Polymers Based on [Mo6Se8(CN)6]7− Anions and Mn2+ Cations

Three novel coordination polymers K₅[MnMo₆Se₈(CN)₆] · 8H₂O (1), (Me₄N)₄[{Mn(H₂O)₂}_1.5Mo₆Se₈(CN)₆] · 4H₂O (2), and K₃[{Mn₂(H₂O)₄}Mo₆Se₈(CN)₆] · 7H₂O (3) have been synthesized by layering of a methanol solution of [Mn(salen)]CH₃COO (salen–N,N′-bis(salicylidene)ethylenediamine) on an aqueous solution of K₇[Mo₆Se₈(CN)₆] · 8H₂O. The compounds have been characterized by single-crystal X-ray diffraction analysis. All structures are based on negatively charged porous polymer frameworks where CN groups of [Mo₆Se₈(CN)₆]⁷⁻ cluster complexes are coordinated to Mn²⁺ cations. Cavities in the frameworks are filled by additional cations and solvate water molecules.     

Chiral coordination polymers based on Re cluster complexes,Cu<Superscript>2+</Superscript> cations,and 1,2<Emphasis Type="Italic">S</Emphasis>,3<Emphasis Type="Italic">S</Emphasis>,4-tetraaminobutane

Reactions of octahedral and tetrahedral chalcocyanide cluster complexes of Re with Cu²⁺ cations and 1,2S,3S,4-tetraaminobutane (Threo-tab) were used to synthesize and study the structures of the following six novel chiral complexes: [{Cu₂(NH₃)(Threo-tab)₃}Re₆S₈(CN)₆] 3H₂O (I) (where Threo is 1,2S,3S,4-tetraaminobutane), [{Cu₂(NH₃)(Threo-tab)₃}Re₆Se₈(CN)₆] 2H₂O (II), [{Cu(Threo-tab)}₂Re₆Te₈(CN)₆] 13.5H₂O (III), [{Cu(Threo-tab)}₂Re₄Te₄(CN)₁₂] 6.5H₂O (IV), [{Cu₂(NH₃)(Threo-tab)₂}Re₄Te₄(CN)₁₂] 4H₂O (V), and [{Cu(NH₃)(Threo-tab)}]₂[Re₄S_3.4Te_0.6(CN)₁₂] 1.25H₂O (VI). The structures of complexes I–IV contain extended channels of sufficiently large size capable of including guest molecules.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 4, 2005, pp. 289–301.Original Russian Text Copyright © 2005 by Mironov, Naumov, Brylev, Efremova, Fedorov, Hegetschweiler.     

Synthesis and structure of a new octahedral molybdenum thiocyanide cluster complex K7[Mo6(μ3-S)8(CN)6]·8H2O

The new octahedral molybdenum thiocyanide cluster complex K₇[Mo₆S₈(CN)₆]·8H₂O was synthesized by excision of the cluster core (the reaction of ZnMo₆S₈ with a melt of KCN). The structure of the complex was established by X-ray diffraction analysis. The reaction of Mo₆Se₈ with a KCN—KSCN mixture afforded the mixed-ligand cluster anions [Mo₆(Se,S)₈(CN)₆]^7–. The salt of composition K_1.5Cs_5.5[Mo₆Se_6.8S_1.2(CN)₆]·8H₂O was obtained. The complexes are isostructural to each other and to the selenium analog described previously. The magnetic properties and the electronic and IR spectra were measured and discussed.