Die elektrochemische Auflösung elementaren Tellurs in ionischen Flüssigkeiten (ionic liquids, ILs) oder flüssigem SO₂ wird als eine neue Methode zur Synthese polykationischer Chalkogencluster vorgestellt. Die benutzten ILs sind Ethylmethylimidazoliumtriflat und Tetraalkylammoniumtriflylimid. Triflylmethanid wurde in Form von [BuMeIm][CTf₃] als Elektrolyt in flüssigem SO₂ eingesetzt. Auf diesem Weg gelang die Isolierung von [Te₄][CTf₃]₂, [Te₆][OTf]₄ und [Te₈][NTf]₂, welche das quadratische [Te₄]²⁺, das prismatische [Te₆]⁴⁺ und das neuartige [Te₈]²⁺ mit Barrelan-Struktur enthalten. Diese Verbindungen haben neuartige Zusammensetzungen, da sie nicht die üblichen Halogenidometallat-Anionen, sondern gebräuchliche, schwach koordinierende Anionen enthalten. Das ¹²⁵Te-NMR-Spektrum einer IL-Lösung, die das [Te₈]²⁺-Ion enthält, zeigt nur ein breites Signal bei +2700 ppm. DFT-Rechnungen zeigen, dass geringe konzertierte Lageverschiebungen innerhalb des [Te₈]²⁺-Clusters zu einer fluktuierenden Molekülstruktur führen. Die Valenzisomerisierung ist schnell und weist eine geringe Aktivierungsbarriere von etwa 8 kJ mol⁻¹ auf.

As a new method for the synthesis of chalcogen polycationic clusters, the electrochemical dissolution of elemental tellurium in ionic liquids (IL) or in liquid SO₂ is presented. ILs used are ethylmethylimidazolium triflate [OTf]⁻ and tetraalkylammonium triflylimide [NTf₂]⁻. Tristriflylmethanide [CTf₃]⁻ was used as [BuMeIm][CTf₃] as the electrolyte in SO₂. This allowed for the isolation of [Te₄][CTf₃]_2, [Te₆][OTf]₄, and [Te₈][NTf₂]₂ containing the square [Te₄]²⁺, the prismatic [Te₆]⁴⁺, and the novel barrelane-shaped [Te₈]²⁺. The compounds are novel compositions as they do not contain the usual halometalate anions, but rather common weakly coordinating anions. The ¹²⁵Te NMR spectrum of an IL solution containing [Te₈]²⁺ features only one broad signal at 2700 ppm. DFT calculations show that slight concerted displacements within the [Te₈]²⁺ cluster lead to a fluxional molecular structure and a fast valence isomerism with a very low activation barrier of about 8 kJ mol⁻¹.

The reactions of elemental antimony, tellurium, selenium and sulfur as well as antimony telluride and antimony sulfide in melts composed of GaCl₃/SbCl₃/ACl (A = Cu⁺, Ag⁺, PPh₄⁺) yielded Ag(Sb₇Te₈)[GaCl₄]₆ (1), (Sb₇Se₈)[GaCl₄]₂[Ga₂Cl₇]₃ (2), (Sb₇Se₈Cl₂)[GaCl₄]₃ (3) and (Sb₇S₈Cl₂)[GaCl₄]₃ (4). SbCl₃ plays the role of the oxidant, and GaCl₃ plays the role of the Lewis acidic chloride ion acceptor. All of the compounds form orange, air-sensitive crystals. The crystal structures consist of discrete, double-cube-shaped, mixed antimony–chalcogen cationic clusters (Sb₇Te₈)⁵⁺, (Sb₇Se₈)⁵⁺, (Sb₇Se₈Cl₂)³⁺ and (Sb₇S₈Cl₂)³⁺. The anions are discrete chloridogallate [GaCl₄]^– and [Ga₂Cl₇]^– anions. All compounds were characterized by single-crystal X-ray diffraction, energy-dispersive electron-beam X-ray fluorescence spectroscopy, Raman vibrational spectroscopy and solid-state ⁷⁷Se NMR spectroscopy. Supporting gas-phase and periodic DFT calculations allowed the assignments of the spectra and provided insights into the bonding situation of the hypervalent Sb atoms.

The novel chalcogenidotellurates(IV) [Zn(NH₃)₆][Zn(NH₃)₄]₂(TeS₃)₃ (1), [Zn(NH₃)₄](TeSe₃) (2), [Mn(NH₃)₆](TeS₃) (3), [Mn(NH₃)₆](TeSe₃) (4) and [Mn(CH₃NH₂)₆](TeSe₃) (5) were obtained by solvothermal reactions from elemental zinc or manganese, tellurium and sulfur or selenium, respectively, in liquid ammonia or methylamine. The reactions were performed in thick-walled glass ampoules at 50 °C and give 1, 2 and 3 in quantitative yield. The yields for 4 and 5 are lower. The crystal structures consist of tetrammine, hexammine and hexakis(methylamine) complexes of divalent Zn and Mn and of trigonal-pyramidal (TeCh₃)^2– (Ch = S, Se) anions. Compounds 1 (P31m) and 2 [two polymorphic forms, Cmc2₁ (2a) and Pca2₁ (2b)] crystallise in a noncentrosymmetric manner in polar structures, while 3 (P2₁/c), 4 (Pbca) and 5 (P2₁/m) are centrosymmetric. As an unique feature, the structure of 1 contains two different types of Zn ammine complexes, tetrahedral [Zn(NH₃)₄]²⁺ and octahedral [Zn(NH₃)₆]²⁺. Compound 5 contains the rare hexacoordinate complex [Mn(CH₃NH₂)₆]²⁺. Raman spectra of 1 and 2 show the two expected symmetric and asymmetric valence vibrations between 350–380 cm^–1 for (TeS₃)^2– and 215–235 cm^–1 for (TeSe₃)^2–.

5-Cyanotetrazole readily forms from (CN)₂ and HN₃. The coordination abilities of the 5-cyanotetrazolate anion N₄CCN^– (ctz) towards Cu^II ions were examined and a series of complexes and coordination polymers were synthesized and characterized by single-crystal structure analyses: PPh₄[Cu(ctz)₃] (1), [Cu(ctz)₂(bipy)] (2, bipy = 2,2′-bipyridine), [CuCl(py)₄](ctz)·2py (3, py = pyridine), [Cu₂(ctz)₆Cu(CH₃CN)₂(H₂O)₂]·2CH₃CN (4a), [Cu₂(ctz)₆Cu(H₂O)₃{(CH₃)₂CO}]·3(CH₃)₂CO (4b), [Cu(ctz)₂(py)₄] (5), [Cu₂(ctz)₄(bipy)₂] (6) and [Cu₂(ctz)₂(tpm)₂(NO₃)]NO₃ [7, tpm = tris(pyrazol-1-yl)methane]. As ctz is a multidentate linker, additional neutral coligands such as monodentate py, bidentate bipy and tridentate tpm ligands were used to avoid the formation of noncrystalline polymers. The structures of 1–7 reflect the versatile coordination abilities of ctz in the various types of coordination environments of the Cu^II ions and dimensionalities of the linkages. The structures represent 1D chain motifs (1, 2 and 3), 2D layered structures (4a and 4b), mononuclear (5) and dinuclear complexes (6 and 7). Magnetic coupling phenomena were detected by susceptibility measurements of 1, 4a, 6 and 7, which were fitted to the magnetic models according to antiferromagnetic spin-pairing of two S = 1/2 systems (Bleaney–Bowers) for 6 (J = –0.53 cm^–1) and 7 (J = –2.91 cm^–1), to the ferromagnetic high-temperature series expansion based on the Baker 1D (S = 1/2) chain model for 1 (J = +14.4 cm^–1) and to the Néel model of ferrimagnetism for 4a. The diverse magnetic interactions between the Cu²⁺ sites are communicated by the bridging ctz anions.

The reactions of thianthrene (TA) and selenanthrene (SeA) with AlCl₃ were studied in the melt phase and with liquid SO₂ as solvent. From neat AlCl₃ and TA, the colorless complex [AlCl₃(TA)] was isolated as the main product and the dark red salt (TA)₃[Al₂Cl₇]₂ as the byproduct. The analogous solvent-free reaction of selenanthrene and AlCl₃ takes a different course as colorless [Al(SeA)₃][Al₂Cl₇]₃ is formed in quantitative yield. With SO₂ as solvent, both TA and SeA give the black radical salts (TA)₂[AlCl₄]₂ and (SeA)₂[AlCl₄]₂, respectively. In the structure of [AlCl₃(TA)], thianthrene acts as a monodentate ligand and coordinates with one S atom to the pyramidal AlCl₃ unit. The structure of the (TA)₃²⁺ ion is a stack of three almost planar TA molecules in parallel arrangement. [Al(SeA)₃]³⁺ represents a tris-chelate complex ion with SeA acting as a bidentate ligand and both Se atoms binding to the octahedrally coordinated Al³⁺ ion. (SeA)₂[AlCl₄]₂ consists of dimers of SeA⁺ radical ions, which are bound by weak intermolecular Se···Se bonds. Tentative reaction equations are given to explain the unexpected oxidation processes that lead to the radical ions. Quantum chemical calculations were performed on the molecular fragments and on the periodical structures. The trimeric (TA)₃²⁺ ion is in the singlet state in accordance with the magnetic properties of (TA)₃[Al₂Cl₇]₂, which show a weak temperature-independent paramagnetism. The ion is bound by long-range four-center bonds between the outer two radicals.

A new (thianthrene)gold(III) complex has been synthesized in liquid SO₂ as the solvent from thianthrene (TA) andAuCl₃. [AuCl₂(TA)₂][AuCl₄] [triclinic, P, a = 9.9832(2) Å, b = 10.3404(2) Å, c = 15.0798(4) Å, α = 75.038(1)°, β = 81.610(1)°, γ = 68.409(1)°, V = 1396.15(5) ų, Z = 2] has a salt-like structure consisting of [AuCl₂(TA)₂]⁺ and [AuCl₄]^– ions, both with square-planar coordinated gold atoms of oxidation state +3. In the cation, two bent TA molecules are coordinated to Au each through one sulfur atom. The title compound is thermally stable up to 425 K and is semiconducting with a conductivity reaching 25 mSm^–1 at 380 K and a low activation energy of 0.43 eV. A model for the charge transport along the stacked cationic complexes is discussed. When dissolved in chloroform [AuCl₂(TA)₂][AuCl₄] is converted into the already known uncharged, mononuclear complex [AuCl₃(TA)], which shows that a polymerization isomerism exists between the two forms.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

The diazotisation of 2,2′-diaminotolane with one equivalent of HNO₂ yields the macrocyclic bis(tolanetriazene) (tolaneN₃H)₂ in moderate yield. As shown by the crystal structure determination, the molecule is essentially planar. After deprotonation, the central cavity is suitable for complexation of transition metal ions. In pyridine solution, the anion (tolaneN₃)₂^2– is formed, which reacts with the acetates of Co²⁺ and Ni²⁺ to the dark red coloured complexes [M((tolaneN₃)₂)(py)₂]. The metal ions are located in the centre of the macrocycles, coordinated by four N atoms of the two triazenide groups. Two pyridine ligands occupy the axial positions, giving the central atoms a distorted octahedral coordination environment. In the temperature range between 30 and 300 K, both complexes show the expected magnetic properties of magnetically isolated ions with nearly fulfilled Curie behaviour and μ_eff = 3.40 for Ni^II and 5.19 for Co^II, which is in the high spin state.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)