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Structurally Defined Zincated and Aluminated Complexes of Ferrocene Made by Alkali-Metal-Synergistic Syntheses

Lookup NU author(s): Professor William Clegg

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Abstract

Reaction of ferrocene with 1 or 2 molar equivalents of the synergistic-operative bimetallic sodium zincate base TMEDA·Na(m-TMP)(m-tBu)Zn(tBu) yields mainly mono- or di-zincated complexes TMEDA·Na(m-TMP)[m-(C₅H₄)Fe(C₅H₅)]ZntBu (1) and [TMEDA·Na(m-TMP)Zn(tBu)]₂(C₅H₄)₂Fe (2). Likewise, the separated pairing of Li(TMP) and (TMP)AliBu₂ in the presence of THF can mono- or dimetalate ferrocene in a synergistic two step lithiation/trans-metal-trapping protocol to give THF·Li(m-TMP)[m-(C₅H₄)Fe(C₅H₅)]Al(iBu)₂ (4) or [THF·Li(m-TMP)Al(iBu)₂]₂(C₅H₄)₂Fe (5). In the absence of Lewis donating co-solvents, a four-fold excess of the sodium zincate appears to produce an unprecedented four-fold zincated ferrocene of formula Na₄(TMP)₄Zn₄(tBu)₄[(C₅H₃)₂Fe] (3); whereas when donor solvent is withheld from the lithium/aluminium pairing only dimetalation of ferrocene is possible. Tetrametalation seems to be inhibited by the in situ generation of TMP(H) via amido basicity which then acts as a Lewis donor towards lithium, preventing inverse-crown formation and preferentially forming the Lewis acid – Lewis base adduct [TMP(H)·Li(m-TMP)Al(iBu)₂]₂(C₅H₄)₂Fe (6). With the exception of 3, all aforementioned complexes have been characterized by X-ray crystallography, while 1 - 6 have also been studied by solution NMR spectroscopic studies.

Publication metadata

Author(s): Clegg W, Crosbie E, Dale-Black SH, Hevia E, Honeyman GW, Kennedy AR, Mulvey RE, Ramsay DL, Robertson SD

Publication type: Article

Publication status: Published

Journal: Organometallics

Year: 2015

Volume: 34

Issue: 11

Pages: 2580-2589

Online publication date: 04/02/2015

Acceptance date: 28/01/2015

ISSN (print): 0276-7333

ISSN (electronic): 1520-6041

Publisher: American Chemical Society

URL: http://dx.doi.org/10.1021/om5012352

DOI: 10.1021/om5012352

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