Oxidation behavior of intramolecularly coordinated unsymmetrical diorganotellurides: isolation of novel tetraorganoditelluronic acids, [RR'Te(μ-O)(OH)2]2

Phenylseleninate-Connected Telluroxane Clusters

Hydrolysis of PhTeI3 in the presence of sodium phenylseleninate and M3+ ions (M = Y, Nd, Ce) gives well-defined, bowl-shaped telluroxane clusters. Each of the two half-spheres of the compositions [(PhTe)18{ML}O24]7+/8+ ({ML} = {Y(NO3)(H2O)}2+ (1), {Nd(NO3)(H2O)2+} (2), or {Ce(NO3)2}+ (3)) are connected by two (compound 3) or four (compounds 1 and 2) PhSeO2- bridges. The resulting chalcogenoxane spheres have internal volumes of approximately 1500 Å3. Charge compensation is provided by nitrate ions and/or [Na2(NO3)8]6- clusters, which are located inside and surrounding these spheres.

N-Coordinated tellurenium(II) and telluronium(IV) cations: synthesis, structure and hydrolysis

A set of N-coordinated tellurium(II) compounds containing either C,N-chelating ligands CNR (where CN = 2-(RNCH)C6H4, R = tBu or Dipp; Dipp = 2,6-iPr2C6H3) or N,C,N pincer ligands NCNR (where NCN = 2,6-(RNCH)2C6H4, R = tBu or Dipp) were synthesized. In the case of C,N-chelated compounds, the reaction of CNDippLi with Te(dtc)2 (where dtc = Et2NCS2) in a 1 : 1 molar ratio smoothly provided the carbamate CNDippTe(dtc) which upon treatment with 2 eq. of HCl provided the chloride CNDippTeCl. In contrast, the analogous conversion of NCNRLi with Te(dtc)2 surprisingly furnished ionic bromides [NCNRTe]Br as a result of the exchange of dtc by Br coming from nBuBr present in the reaction mixture. Furthermore, the reaction of CNDippTeCl or [NCNRTe]Br with silver salts AgX (X = OTf or SbF6) provided the expected tellurenium cations [CNDippTe]SbF6 and [NCNRTe]X. To further increase the Lewis acidity of the central atom, the oxidation of selected compounds with 1 eq. of SO2Cl2 was examined yielding stable compounds [CNtBuTeCl2]X and [NCNtBuTeCl2]X. The oxidation of the Dipp substituted compounds proved to be more challenging and an excess of SO2Cl2 was necessary to obtain the oxidized products [CNDippTeCl2]SbF6 and [NCNDippTeCl2]SbF6, which could solely be characterized in solution. Compounds [CNtBuTeCl2]OTf and [NCNtBuTeCl2]OTf were shown to undergo a controlled hydrolysis to the corresponding telluroxanes. All compounds were studied by multinuclear NMR spectroscopy in solution and for selected compounds solid state 125Te NMR spectroscopy and single-crystal X-ray diffraction analysis were performed. The Lewis acidity of the studied cations was examined by the Gutmann-Beckett method using Et3PO as the probing agent. The Te-N chalcogen bonding situation of selected compounds has also been examined computationally by a set of real-space bonding indicators.

A Base-Free Copper-Assisted Synthesis of C2-Symmetric Spirotelluranes and Biaryls Based on Divergent Stoichiometry of Na2Te

A one pot Cu(I)-assisted synthetic methodology has been developed for the preparation of biologically important C2-symmetric spirodiaza, benzyloxy, benzoxytelluranes from 2-bromo-N-aryl benzamides, benzyl alcohols, and benzoic acid by using tellurium...

A tellura-Baeyer-Villiger oxidation: one-step transformation of tellurophene into chiral tellurinate lactone

Baeyer-Villiger (BV) oxidation is a fundamental organic reaction, whereas the hetero-BV oxidation is uncharted. Herein, a tellura-BV oxidation is discovered. By oxidizing a tellurophene-embedded and electron-rich polycycle (1) with mCPBA or Oxone, an oxygen atom is inserted into the Te-C bond of the tellurophene to form tellurinate lactone mono-2. This reaction proceeds as follows: (i) 1 is oxidized to the tellurophene Te-oxide form (IM-1); (ii) IM-1 undergoes tellura-BV oxidation to give mono-2. Moreover, the hybrid trichalcogenasumanenes 7 and 8 are, respectively, converted to tellurinate lactones mono-9 and mono-10 under the same conditions, indicating that tellura-BV oxidation shows high chemoselectivity. Due to the strong secondary bonding interactions between the Te[double bond, length as m-dash]O groups on tellurinate lactones, mono-2, mono-9, and mono-10 are dimerized to form U-shaped polycycles 2, 9, and 10, respectively. Notably, mono-2, mono-9, mono-10, and their dimers show chirality. This work enables one-step transformation of tellurophene into tellurinate lactone and construction of intricate polycycles.

Isolation of the novel example of a monomeric organotellurinic acid

The synthesis of the first example of a monomeric, stable organotellurinic acid is reported by utilizing the σ-hole participation of the Te atom with the N atom of the 2-(2′-pyridyl)phenyl moiety.