Zweikernige Pentamethylcyclopentadienyl-Vanadium-Komplexe mit Tellurbrücken. Anwendung der 51V NMR-Spektroskopie zur Identifizierung neuer Vanadium-Verbindungen mit unterschiedlichen Chalkogenen im Brückensystem

Abstract

Solutions of the kinetically labile tricarbonyl vanadium halfsandwich complexes Cp*V(CO)3L (L = SMe2, MeCN) react with elemental tellurium in the presence of sodium polytelluride (of the approximate composition Na2Te5) to give the binuclear μ-oxo complex Cp*2V2Te3O (4e). The reactions of 4e, in tetrahydrofuran solution, with chalcogen sources such as elemental chalcogens (S8, Sen), chalcogen hydrides (H2S, H2Se), chalcogenides (Na2Se) and polychalcogenides (Na2S22, Na2Se5) have been used to prepare mixed tetrachalcogenide complexes of the types Cp*2V2E4 (2) and Cp*2V2E3O (4) (E = S, Se and Te) which contain various S/Se/Te combinations in the bridge system between the two vanadium centers. μ-Oxo ditelluride complexes such as Cp*2V2Te2EO (E = S (4i), Se (4j) are formed when 4e is treated with sodium chalcogenides (Na2S22, Na2Se) for short periods of time. Oxygen-free ditelluride complexes such as Cp*2V2Te2E2 (E = S (2f), Se (2g)) have been obtained by the reactions of Cp*2V2E3 (E = S (3a), Se (3b)) with Na2Te5. Monotelluride complexes such as Cp*2V2TeE2O (E = S (4f), Se (4h)) and Cp*2V2TeSeSo (4g) can be identified as components of mixtures and characterised by 51V NMR spectroscopy and FD mass spectroscopy. Total displacement of the substitution-labile tellurium bridges in Cp*2V2Te2S2 (2f) and Cp*2V2Te2SO (4i) using polysulfide or polyselenide leads to the corresponding sulfide-and selenide-bridged complexes in high yields. The spectroscopic data of the telluride compounds are discussed and compared with the corresponding data of the sulfide and selenide analogues.