Intensely luminescent homoleptic alkynyl decanuclear gold(I) clusters and their cationic octanuclear phosphine derivatives

Treatment of Au(SC(4)H(8))Cl with a stoichiometric amount of hydroxyaliphatic alkyne in the presence of NEt(3) results in high-yield self-assembly of homoleptic clusters (AuC(2)R)(10) (R = 9-fluorenol (1), diphenylmethanol (2), 2,6-dimethyl-4-heptanol (3), 3-methyl-2-butanol (4), 4-methyl-2-pentanol (4), 1-cyclohexanol (6), 2-borneol (7)). The molecular compounds contain an unprecedented catenane metal core with two interlocked 5-membered rings. Reactions of the decanuclear clusters 1-7 with gold-diphosphine complex [Au(2)(1,4-PPh(2)-C(6)H(4)-PPh(2))(2)](2+) lead to octanuclear cationic derivatives [Au(8)(C(2)R)(6)(PPh(2)-C(6)H(4)-PPh(2))(2)](2+) (8-14), which consist of planar tetranuclear units {Au(4)(C(2)R)(4)} coupled with two fragments [AuPPh(2)-C(6)H(4)-PPh(2)(AuC(2)R)](+). The titled complexes were characterized by NMR and ESI-MS spectroscopy, and the structures of 1, 13, and 14 were determined by single-crystal X-ray diffraction analysis. The luminescence behavior of both Au(I)(10) and Au(I)(8) families has been studied, revealing efficient room-temperature phosphorescence in solution and in the solid state, with the maximum quantum yield approaching 100% (2 in solution). DFT computational studies showed that in both Au(I)(10) and Au(I)(8) clusters metal-centered Au → Au charge transfer transitions mixed with some π-alkynyl MLCT character play a dominant role in the observed phosphorescence.     

The first homoleptic gold(I) thiosulfonate complex

A gold(I) thiosulfonate complex, Et(4)N[Au(MeS(2)O(2))(2)], is reported in which gold(I) ions are coordinated by the terminal sulfur atoms from two MeS(2)O(2)(-) ligands in a linear geometry. Two anionic units are linked by an aurophilic interaction forming discrete anionic dimers, [Au(MeS(2)O(2))(2)](2)(2-), which exhibit a shorter Au···Au distance (by 0.2 ?) and smaller dihedral angle than the thiosulfate analogue.     

Suzuki coupling catalyzed by a homoleptic Pd(I)-Pd(I) solvento complex

The Pd^I-Pd^I bonded complex [Pd₂(CH₃CN)₆][SbF₆]₂ is catalytically active towards Suzuki cross-coupling reactions of aryl bromides or chlorides with various arylboronic acids under mild conditions giving good to excellent yields. Its performance is enhanced by the introduction of stoichiometric or limited phosphines. The effects of different ligands, metal oxidation states [Pd(II), Pd(I) Pd(0)], bases and solvents have been examined.     

A modified method of separating Tl(I) and Tl(III) in aqueous samples using solid phase extraction

In spite of the development of new measurement techniques in recent years, the rapid and accurate speciation of thallium in environmental aqueous samples remains a challenge. In this context, a novel method of solid phase extraction (SPE), involving the anion exchange resin AG1-X8, is proposed to separate Tl(I) and Tl(III). In the presence of diethylene triamine pentacetate acid (DTPA), Tl(III) and Tl(I) can be separated by selective adsorption of Tl(III)-DTPA onto the resin, Tl(III) is then eluted by a solution of HCl with SO₂. The validity of this method was confirmed by assays of standard solutions of Tl(I) and Tl(III). The proposed method is shown to have an outstanding performance even in solutions with a high ratio of Tl(I)/Tl(III), and can be applied to aqueous samples with a high concentration of other electrolytes, which could interfere with the measurement. Portable equipment and reagents make it possible to use the proposed method routinely in the field.     

Thermal decomposition of Cu(I) phosphine complexes

The thermal decomposition of Cu(I) phosphine complexes of the general types (CuXPPh₃)₄, [CuX(PPh₃)₂] and [CuX(PPh₃)₃] was investigated.The thermal decomposition of (CuXPPh₃)₄, where X denotes Cl^–, Br^–, I^–, NO ₃ ^– and PPh₃=P(C₆H₅)₃, occurs with formation of a phosphine oxide intermediate. For the remaining complexes this intermediate was not proved in the thermal decomposition.

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Zusammenfassung Die thermische Zersetzung der Cu(I)-Phosphinkomplexe vom allgemeinen Typ (CuXPPh₃)₄ und [CuX(PPh₃)₂], wie auch [CuX(PPh₃)₃] wurde untersucht. Die thermische Zersetzung von (CuXPPh₃)₄, wobei X=Cl^–, Br^–, I^– und NO ₃ ^– bedeutet und PPh₃=P(C₆H₅)₃, verläuft unter Bildung eines Phosphinoxid Zwischenproduktes, bei den übrigen Komplexen konnte dieses im Laufe der thermischen Zersetzung nicht nachgewiesen werden.

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Résumé On a étudié la décomposition thermique des complexes phosphine-Cu(I) de formule générale (CuXPPh₃)₄, [CuX(PPh₃)₂], [CuX(PPh₃)₃]. La décomposition thermique de (CuXPPh₃)₄, où X désigne Cl^–, Br^–, I^– et NO ₃ ^– , et PPh₃=P(C₆H₅)₃, s'effectue avec formation d'un oxyde de phosphine intermédiaire; avec les autres complexes, cet intermédiaire n'a pas été mis en évidence au cours de la décomposition thermique.

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(CuXPPb₃)₄ [CuX(PPh₃)₂] [CuX(PPh₃)₃]. (CuXPPh₃)₄, X=Cl^–, Br^–, I^–, NO ₃ ^– , PPh₃=(₆₅)₃ . .

     

Features of EPR spectra of complexes of ortho-benzoquinones with Tl(I) and Tl(III) diethyldithiocarbamates

A study has been made of the EPR spectra of Tl(l) and Tl(III) o-semiquinolates, obtained by the interaction of o-benzoquinones with thallium amalgam and thallium(III) diethyldithiocarbamate, respectively. A strong temperature dependence has been found for the constant of hyperfine coupling (HFC) with the metal nucleus in thallium(III) 3,5-di-tert-butyl-o-semiquinolate; this is explained by the presence of competing mechanisms of spin transfer from the o-semiquinone ligand to the metal. Cation exchange and effective complexation of the Tl(I) o-semiquinolate with thallium diethyldithiocarbamate have been observed. The kinetic parameters of exchange have been determined.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 786–790, April, 1990.     

A vibrational spectroscopic study of tris triphenyl phosphine rhodium (I) chloride

In this work we report the first Raman spectrum of tris triphenyl phosphine rhodium (I) chloride. The vibrational spectrum of triphenyl phosphine has also been recorded under similar conditions to facilitate comparisons. FT-Raman spectra and diffuse reflectance mid-IR and far-IR spectra are presented and a full skeletal vibrational assignment is made.     

Separation of Tl(I)-Pb(II) by liquid-liquid extraction with diethyldithiocarbamic acid isolation of201Tl

The production of²⁰¹ Tl is described. Natural thallium is irradiated with protons and the induced²⁰¹Pb is separated from the target by liquid-liquid extraction with diethyldithiocarbamic acid in chloroform.²⁰¹Tl is separated from the mother activity (²⁰¹Pb) by liquid-liquid extraction with the same reagent. The decontamination of the final product (carrier free²⁰¹TlCl) is ≥5·10⁶ from the thallium of the target and>5×10⁴ from lead isotopes.     

Organometallic polymers. I. Synthesis of ferrocene-containing poly(phosphine oxides) and poly(phosphine sulfides)

Poly(phosphine oxides) and poly(phosphine sulfides) of ferrocene were synthesized in the melt phase. The resulting ferrocene polymers, linked by phosphorus bridges, were thermally stable and infusible solids, of low molecular weight (M?_n < 4000). Phenyldichlorophosphine, phenyldichlorophosphonate, and phenylphosphonothioic dichloride were copolymerized with ferrocene in the melt phase (80–110°C.) with ZnCl₂ as a catalyst. As the polymerization temperature was raised, cleavage of cyclopentadiene rings from iron became more pronounced, and cyclopentane-bridged polymers of ferrocene were produced in competition with the ferrocene–phosphorus polymers. The cleavage-polymerization process became predominant at 140°C. The structures of poly(phosphine oxides) (and sulfides) of ferrocene were verified by infrared and nuclear magnetic resonance spectroscopy.     

A homoleptic hydrotris(methimazolyl)borate complex of titanium

The reaction of [Ti(2)(micro-Cl)(2)(thf)(2)(eta-C(8)H(8))(2)] with Na[HB(mt)(3)] (mt = methimazolyl) provides the unusual salt [Ti{HB(mt)(3)}(2)][TiCl(4)(thf)(2)], the cation of which features homoleptic Ti(III)S(6) coordination.     

(Fluoroalkyl)phosphine complexes of nickel(0) and cobalt(I)

The synthesis of a series of (fluoroalkyl)phosphine complexes of nickel is reported. Treatment of (cod)₂Ni with dfepe (dfepe=(C₂F₅)₂PCH₂CH₂P(C₂F₅)₂) yields (dfepe)Ni(cod) (1), which has been structurally characterized. Treatment of 1 with CO or bipy results in the formation of (dfepe)Ni(CO)₂ (2) and (dfepe)Ni(bipy) (3), respectively. Addition of excess dfepe to 1 results in incomplete cod displacement to form (dfepe)₂Ni (4). The homoleptic complex 4 may be independently prepared in high yield by reduction of (acac)₂Ni with (ⁱBu)₃Al in the presence of butadiene and excess dfepe. Solvation of (dfepe)Ni(cod) in acetonitrile gives a new complex tentatively identified as (dfepe)Ni(MeCN)₂ (6), whereas dissolution of (dfepe)₂Ni in acetonitrile leads to a mixture of 6 and the partial displacement product (dfepe)(η¹-dfepe)Ni(MeCN) (5). In contrast to (R₃P)₄Ni(0) phosphine and phosphite complexes, which undergo protonation by strong anhydrous acids such as HCl, H₂SO₄ and CF₃CO₂H to give (R₃P)₄Ni(H)⁺ products, Treatment of (dfepe)₂Ni with neat CF₃CO₂H or excess HOTf in dichloromethane gave no spectroscopic evidence for (dfepe)₂Ni(H)⁺. Exposure for extended periods leads to dfepe loss and decomposition to Ni(II) products. The synthesis of the first cobalt complex of dfepe, (dfepe)Co(CO)₂H, is also reported.     

A multi-receptor fluorescence signaling system exhibiting enhancement selectively in presence of Na(I) and Tl(I) ions

A PET fluorescence signaling system L₁ has been synthesized in the ‘Receptor1-Spacer-Fluorophore-Spacer-Receptor2’ format through attachment of a laterally non-symmetric heteroditopic cryptand and a 4,7,10,13-tetraoxa-1-azacyclopentadecane macrocycle at the 9- and 10-positions of anthracene. The cryptand receptor is derivatized with two 2,4-dinitrobenzene groups to impart structural rigidity. This system exhibits selective fluorescence enhancement in presence of Na(I) and Tl(I) ions simultaneously and mimics the AND logic function. The cryptand receptor also binds a Cu(II) ion outside the cavity and allows L₁ to perform as an INHIBIT chemical logic in presence of H⁺ and Cu(II) ions.