Mehrfachbindungen zwischen Hauptgruppenelementen und Übergangsmetallen. LVII. Alkyl- und Aryl-Komplexe der Organorhenium-Reihe

Both the mono- and dialkyl derivatives formulated as (η⁵-C₅Me₅)ReO(Cl)R (4f-g) and (η⁵-C₅Me₅)ReOR₂ (3a-g), respectively, are formed upon treatment of dichloro(oxo) (η⁵-pentamethylcyclopentadienyl)rhenium(V) (1) with the corresponding Grignard reagents. The dimethyl- (3a), dibenzyl- (3e), diphenyl (3f), and trimethylsilylmethyl- (4g) complexes were characterized by single crystal X-ray diffraction studies. The highest degree of unsymmetry of the C₅Me₅ complexation is found in the diphenyl derivative 3f. This effect to a large extent is attributable to the pronounced trans influence of the oxo ligands. The crystallographically characterized η³-allyl complex (η⁵-C₅Me₅)Re(η³-C₃H₅)Br₂ (5) of pseudo-tetrahedral geometry is formed from 1 and allylmagnesium bromide. Reaction of the "di-Grignard reagent" (CH₃)₂C(CH₂MgBr)₂ (2i) with 1 yields the first stable rhenacyclobutane (η⁵-C₅Me₅)Re(CH₂C(CH₃)₂CH₂)O (3i).