Molecular structure of Te(OMe)(4)center dot ClTe(OMe)(3), a model for ligand exchange between Te(IV) centers

ClTe((OPr)-Pr-i)(3) could be prepared from stoichiometric amounts of TeCl4 and Te((OPr)-Pr-i)(4), a reaction that requires the exchange of ligands bet ween different Te centers. Ligand redistribution between telluranes was stu died, and rapid exchange of -Cl and -OR (R = Me,Pr-i) ligands in solutions df several binary mixtures of Te(OMe)(4), Te((OPr)-Pr-i)(4), ClTe(OMe)(3), and ClTe((OPr)-Pr-i)(3) was established by multinuclear NMR spectroscopy. T he solid-state structure of Te(OMe)(4). ClTe(OMe)(3), the first structurall y characterized adduct between different telluranes, was investigated by si ngle-crystal X-ray diffraction. It exhibits a very short Te-O . . . Te brid ge between the two Te centers and additional Te . . .O and Te . . . Cl cont acts between different adduct molecules. Selected structural parameters of Te(OMe)(4). ClTe(OMe)(3) are Te1-Cl1 274.6(3), Te1-O13 191.0(5), Te1-O12 19 4.9(6), Te1-O11 200.9(7), Te1 . . . O24 26.8(5), Te1 . . . 11a 314.2(8), Te 2-O21 191.6(5), Te2-O22 198.7(5), Te2-O23 190.1(5), Te2-O24 225.35), Te2 . . . O13 307.8(6), and Te2 . . . O22b 269.2(6) pm and Te2-O24 . . . Te1 126. 1(2)degrees. Ab initio (MP2/LANL2DZP) geometry optimization of the model co mpound Te(OH)(4). . . ClTe(OH)(3) revealed that the central Te-O . . . Te b ridge is less symmetric and hence weaker in the isolated adduct molecule th an in the solid state. The stability of Te(OMe)(4). . . ClTe(OMe)(3) toward decomposition in Te(OMe)(4) and ClTe(OMe)(3) is attributed to the strength s of the short Te-O . . . Te bridge between Te(OMe)(4) and ClTe(OMe)(3). On the basis of the molecular structures of Te(OH)(4). ClTe(OH)(3) and Te(OMe )(4). ClTe(OMe)(3), a mechanism for the exchange of -OR groups between Te(I V) centers is proposed.