Synthesis and Reactivity of Functionalized Dimethylgermyl Complexes of the Formula (η⁵-C₅H₅)Re(NO)(PPh₃)(GeMe₂X); Equilibria Involving the Dimethylgermylene Complex [(η⁵-C₅H₅)Re(NO)(PPh₃)(=GeMe₂)]• TfO⁻

Abstract

Addition of Me₂GeCl₂ to Li⁺ [(η⁵-C₅H₅)Re(NO)(PPh₃)] gives the chiral rhenium dimethylchlorogermyl complex (η⁵-C₅H₅)Re(NO)(PPh₃)(GeMe₂Cl) (92%), which reacts with LiAlH, and Me₃SiOTf to yield (n⁵-C₅H₅)Re(NO)-(PPh₃)(GeMe₂H) (74%) and (η⁵-C₅H₅)Re(NO)(PPh₃)(GeMe₂OTf) (3; 94%), respectively. Reactions of 3 and halide salts give (η⁵-C₅H₅)Re(NO)-(PPh₃)(GeMe₂X) (X=F, Br, I; 81–83%). All compounds exhibit two ¹H/ ¹³C NMR signals for the diastereotopic GeMe ₂ groups at ambient temperature, except 3 for which coalescence occurs at 211 K (Δ≠=9.6 ± 0.2 kcal/mol). This is interpreted as indicating a rapid equilibrium with the dimethylgermylene complex [(n⁵-C₅H₅)Re(NO)(PPh₃)(=GeMe₂)]⁺ TfO⁻.

Key Words:

• Chiral rhenium germyl complexes
• germylene intermediate