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.


General Considerations
Commercially purchased starting materials were used as received without further purifications.
Phenyltellurium triiodide (PhTeI3) and phenylseleninic acid (PhSeO2H) were synthesized according to the literature. 1,2The synthesis of the clusters was carried out using a vacuum-line and Schlenk technique under an argon atmosphere.Elemental analyses were performed on vacuum-dried samples.

Physical Measurements
Elemental analysis (CHNS) was determined with a Perkin-Elmer CHN 2400 elemental analyzer.
Mass spectrometric experiments (ESI-MS) have been carried out with CHCl3 solutions on a Synapt G2-S HDMS system equipped with a Z-Spray ESI source (Waters Co., Milford, MA, USA).
UV-vis spectra were measured in CHCl3 on a UV-vis 1650-PC Shimadzu spectrometer in the wavelength range between 250 and 800 nm and a data interval of 0.2 nm.The melting points were determined on a Microquímica MQAPF-301 melting point apparatus and are uncorrected.
FT-IR spectra were measured using a Bruker LUMOS spectrometer in the wavenumber range of 600-4000 cm -1 .Confocal Raman spectra (3600-50 cm -1 ) were recorded on a Bruker Senterra micro-Raman spectrometer using a 785 nm laser line (diode laser), which was focused onto the samples by a 20x Olympus objective (NA 0.40).Thermogravimetric analyses (TGA) were performed using a TGA Q500 (TA Instrument) at a heating rate of 1 °C min -1 , under a continuous flow of nitrogen gas (rate 45 mL min -1 ) in the temperature range of 1-950 °C.
Single-crystal data were collected with a Bruker D8 Venture diffractometer operating with an Incoatec X-ray source with Montel two-dimensional optics, Mo-Ka radiation (l = 0.71073 Å), and a Photon 100 detector.4][5] The positions of the hydrogen atoms were calculated for idealized positions.Crystal data and more details regarding the data collection and refinement of compounds are discussed in a separate section.CCDC 2172185 and CCDC 2337905 contain the supplementary crystallographic data for compounds 1 and 3.These data can be obtained free of charge at http://www.ccdc.cam.ac.uk, from the Cambridge Crystallographic Data Centre, at 12 Union Road, Cambridge CB2 1EZ, UK; via fax: (+44) 1223-336-033; or via e-mail: deposit@ccdc.cam.ac.uk).

Thermogravimetry (TGA)
In order to estimate the amount of co-crystallized solvent 1,4-dioxane and to study the decomposition of the compounds, the thermal behaviour of crystalline samples of pure crystalline samples of the three clusters were studied by TGA analyses.The results are depicted in Figure S1 showing the mass variation (green curves) and its first derivative (blue curves).The analysis was carried out under a nitrogen atmosphere by heating the samples in a platinum pan, in the range 1 -950°C, and a rate of 1 deg min -1 .

Figure S1. TGA graphs of compounds 1 -3.
All three compounds are essentially stable up to approximately 200°C.Interestingly, no defined release of the solvent molecules below this temperature could be found, but a continuous weight loss.The observed weight loss is in approximate agreement with the findings of the crystallographic studies, where approximately twelve and sixteen equivalents of dioxane have been assigned for compounds 1 and 3, respectively, based on partially resolved molecules and the final electron counts in the solvent-accessible areas by a solvent mask in OLEX2). 5e ongoing decompositions at higher temperatures show remarkably similar features for the three cluster compounds.They decompose between 200 and 250°C under complete release of all organic components (including the PhSeO2 -building blocks), the remaining solvent molecules, the M 3+ and Na + ions as well as the nitrate counter ions.The measured weight loss corresponds to the formation of an oxidic material, which consists of a more or less defined mixture of TeO2 and elemental tellurium.Such mixtures have occasionally been found to possess a remarkable stability and are sometimes interpreted as 'Te(II) oxide'. 6This is supported by the detection of consecutive smaller, but defined degradation steps at higher temperatures.Unfortunately, the formed products were amorphous and could not be studied crystallographically. Thus, at the present stage details about the individual products of the thermal degradation cannot be derived from the existing data.

X-Ray diffraction
Some problems were found during the integration of data and refinements of structures, which do not occur in small molecules.RIGU and SIMU commands were applied during the refinements.
A summary of the crystal data and the refinement parameters is provided in Table S1.

Computational Details
The DFT calculations were performed using Gaussian 16. [7] The initial geometries for the optimizations were derived from the previously optimized structure of [{(PhTe)18O24Ca-(H2O)2)}2I16] [8] using GaussView. [9]The obtained geometries were reoptimized until the absence of imaginary frequencies verified a true energetic minimum.The light atoms C and H were modelled by simple 3-21G basis functions, [10] while for O, Ca, Se and I LANL2DZ was used. [11,12][14] For Ca, Se, I and Te, the corresponding effective core potential was used due to the excessive number of atoms involved in each computation.[17] Further analyses of the obtained wave-functions was performed with the free multifunctional wavefunction analyzer Multiwfn. [18]The electron localization function, Laplacian, localized orbital locator and reduced density gradient (RDG) [19] mappings were generated as implemented in Multiwfn with a grid spacing of 2000 x 2000 points.Energies are given in atomic units (a.u.) or kJ/mol as indicated.
The optimized structures are shown in Figures S19-S28, while the general idea behind the stepwise substitution is given in visualized in Figure S29 as a schematic cut through the xy-(or iodide) plane.The relative energies are compared in Table S2, while the results of NBO analysis indicating a reasonably similar overall interaction energy between iodide and tellurium compared to phenyl seleninate and tellurium are given in Table S3, while comparable descriptors for the alliodide reference [{(PhTe)18O24Ca(H2O)2)}2I16] are given in Table S4.]. [8] Figure S28.Top-view of the gas-phase optimized structure of [{(PhTe)18O24Ca(H2O)2)}2I16]. [8]           ]. [8]
0633, wR2 = 0.1760 Final R indexes [all data] R1 = 0.0897, wR2 = 0.2319 R1 = 0.0804, wR2 = 0.1818 Largest diff.peak/hole / e Å -3 4.12/-3.523.64/-3.88CCCD deposit 2172185 2337905 * Solvent masks were calculated, and 552 electrons were found in a volume of 2542 A 3 in one void per unit cell for compound 1 and 733 electrons were found in a volume of 3858 A 3 in one void per unit cell for compound 3.These values are consistent with the presence of 12 molecules of solvent dioxane in compound 1 and 16 molecules dioxane in compound 3. in both compounds.ISOR instructions have been used for the treatment of unusual thermal ellipsoids of carbon and oxygen atoms in compound 1.Ellipsoid representations of the resulting asymmetric units are shown in Fig. S2.

Figure S2 .
Figure S2.Ellipsoid representations of the asymmetric units of compounds 1 and 3 including the ISOR-refined C atoms and disordered nitrate anions and phenyl rings.Ellipsoids are depicted at mainly 30% probability.Hydrogen atoms were omitted for clarity.

Figure S3 .
Figure S3.Representation of the complete structure of compound 3 Hydrogen atoms were omitted for clarity.

Figure S6 .
Figure S6.Top view to the tellurium oxide networks with the central Y 3+ and Ce 3+ ions of compounds 1 and 3. Solid lines represent Te-O distances between 1.83 and 2.4 Å, dashed lines such between 2.4 and to 3.6 Å (sum of the van der Waals radii).

Figure S29 .
Figure S29.Schematic representation of the considered relative energies of consecutive I→PhSeO2 exchanges.

Table S1 .
Crystal data and structure determination parameters.

Table S2 .
Relative energies of consecutive I→PhSeO2 exchanges.