Spectroscopic and Structural Studies on Polyfluorophenyl Tellurides and Tellurium(IV) Dihalides

Abstract

Bis(fluorophenyl) tellurides R2Te (R = C6F2H3 (1), CF3C6F4 (2), CF3C6F4OC6F4 (3), and C6F5 (4)) are synthesized by the facile reaction of Na2Te with bromo-fluorobenzenes, RBr. The corresponding bis(fluorophenyl)tellurium(IV) dihalides, R2TeHal2 (Hal = F, Cl, and Br) (5-16), are obtained by the oxidation of 1-4 with mild halogenating agents (XeF2, SO2Cl2, and Br2). The dihalides show temperature-dependent NMR spectra. On the basis of the 19F NMR spectra of the two series, (C6F2H3)2TeHal2 (Hal = F (5), Cl (9), and Br (13)) and R2TeCl2 (R = C6F2H3 (9), CF3C6F4 (10), CF3C6F4OC6F4 (11), and C6F5 (12)), the coalescence temperatures, T(c), and free enthalpies, DeltaG, of rotation of the TeC bonds are determined. The activation enthalpies for the dichlorides/dibromide 9-13 are in the range of 14.4-15.2 kcal mol(-1) and that for the difluoride 5 is considerably lower at 10.7 kcal mol(-1). In addition to thorough spectroscopic characterization of 1-16, the crystal structures of the monotellurides 2 and 4 as well as of the tellurium(IV) dihalides 5, 6, 9, 10, and 13 were determined. The dihalides show interesting intermolecular Te...Hal contacts, significantly shorter than the sum of the van der Waals radii, leading to different networks of association.

Experimental and Theoretical Studies of Homoleptic Tellurium Cyanides Te(CN)x: Crystal Structure of Te(CN)2

“…Whereas the calculated gas phase structures of 1 at all theoretical levels applied have the expected C 2v symmetry with a CϪTeϪC angle of about 95°(see Table 1), comparable to TeCl 2 in the gas phase with 97.0(6)°, [10] the crystal structure of 1 reveals two almost identical TeϪC bond lengths [2.090(5) and 2.091(6) Å ], but two slightly different CϪN bond lengths [1.131 (7) and 1.149 (7) Å ], with a CϪTeϪC angle of 85.4(2)°(see Figure 2). The TeϪC distance in 1 is in the same range as found for diaryl-substituted tellanes Ar 2 Te, [13] but with a more acute CϪTeϪC angle than the latter. Available structural data for S(CN) 2 and Se(CN) 2 , as far as their poor quality allows conclusions, suggest a different structure in the solid state with CϪS and SeϪC angles of 96 and 99°, respectively.…”

Synthesis and Structures of Triorganotelluronium Pseudohalides

“…The dicyanoargentates 5 and 8 were obtained in an attempt to prepare telluronium cyanides. Low-temperature 13 C NMR spectroscopy of the [Ag(CN) 2 ] − ion in solution has been carried out, with determination of the 13 C− 107/109 Ag coupling.…”

Synthesis and Structures of Cycloalkanetellurium(IV) Fluorides and Azides

“…The molecules are located on twofold rotation axes passing through the tellurium atom and exist as infinite chains with secondary Te···F contacts. The Te-F bond is 2.02Å, which is very similar for example to that found in Mes 2 TeF 2 (2.01Å), Mes = 2,4,6-trimethylphenyl [21], Scheme 3. and slightly longer than in the perfluoroaryl derivative (4-CF 3 C 6 F 4 ) 2 TeF 2 (1.96Å) [5].…”