Axially asymmetric metal alkyls. Part 5. Synthesis and reduction to ZrIII species of group 4 metallepines [ML(η-C5H5)2] [L = (2-CHRC6H4)22-, R = H, M = Ti, Zr, or Hf)], isomers of [ZrL(η-C5H5)2] (R = SiMe3), and... ... meso-[M{1,8-(CHSiMe3)2C10H6}(η-C5H5)2](M = Zr or Hf); X-ray crystal structures of [TiL(η-C5H5)2](R = H) and λ- and δ-RS-[ZrL(η-C5H5)2](R = SiMe3)

Lutz M. Engelhardt, Wing Por Leung, Rocco I. Papasergio, Colin L. Raston, Paul Twiss, Allan H. White

Research output: Contribution to journalArticle

Abstract

Treating [MCl2(η-C5H4R′)2] with a di-Grignard reagent and/or a dilithium reagent based on (2-CHRC6H4)22–(L) yields the metallacycles [ML(η-C5H4R′)2](R = R′= H, M = Ti, Zr, or Hf; R = H, R′= SiMe3, M = Zr)(5), and a mixture of diastereoisomers of λ-RS- and δ-RS-[ZrL(η-C5H5)2](R = SiMe3)(6a), and λ-RR-and δ-SS-[ZrL(η-C5H5)2](R = SiMe3)(6b). Compound (6a) was readily converted to (6b) by photolysis in hexane. The ‘strained’ metallacycles meso-[M{1,8-(CHSiMe3)2C10H6}(η-C5H5)2](M = Zr or Hf)(7) were prepared from an intrinsically unstable dilithium reagent. Reduction of (5),(6a) and (6b), and (7) chemically and electrochemically shows that the generated d1 species are stable at ca. 20 °C except for M = Hf, and that for (5)[and possibly (6a) and (6b)] reduction is associated with metal–carbon bond rupture. The structures of (5)(M = Ti) and (6a) have been established from single-crystal X-ray diffraction data [Ti–Cα 2.207Å, Cα–Ti–Cα 87·8°, dihedral angle between phenyl groups, φ 62.2°; Zr–Cα 2.338Å, Cα–Zr–Cα 98.3(2)°, φ 73.6°].

Original languageEnglish
Pages (from-to)2347-2357
Number of pages11
JournalJournal of the Chemical Society, Dalton Transactions
Issue number10
DOIs
Publication statusPublished - Oct 1987
Externally publishedYes

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