Metal complexes derived from a bidentate ligand possessing two chiral centres, o-C6H4[CH(SiMe3)–]2; stereospecific synthesis of the meso-metallocycles [M{CH(SiMe3)C6H4CH(SiMe3)-o}(η-C5H5)2] and their reversible one-electron reduction

Abstract

Reaction of [M(η-C₅H₅)₂Cl₂](M = Ti, Zr, or Hf) with o-C₆H₄[CH(SiMe₃)Li(tmeda)]₂(tmeda = Me₂NCH₂CH₂NMe₂) in OEt₂ is stereospecific, generating the meso-metallocycle [[graphic omitted]H(SiMe₃)-o}(η-C₅H₅)₂], (1), in high yield; cyclic voltammetry of complexes (1) in tetrahydrofuran shows a reversible one-electron reduction (–E_½^red: Hf > Zr >> Ti) to yield relatively persistent M^III anions (t_½ > 10 s) characterised by their e.s.r. spectra.