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

摘要

Reaction of ferrocene with 1 or 2 molar equiv of the synergistic-operative bimetallic sodium zincate base TMEDA center dot Na(mu-TMP)(mu-tBu)Zn(tBu) yields mainly mono- or dizincated complexes TMEDA center dot Na(mu-TMP) [mu-(C5H4)Fe(C5H5)]ZntBu (1) and [TMEDA center dot Na(mu-TMP)Zn(tBu)](2)(C5H4)(2)Fe (2). Likewise, the separated pairing, of Li(TMP) and (TMP)AliBu(2) in the presence of THF can mono- or dimetalate ferrocene in a synergistic two-Step lithiation/trans-metal-trapping protocol to give THF center dot Li(mu-TMP)[mu-(C5H4)Fe(C5H5)]Al-(iBu)(2) (4) or [THF center dot Li(mu-TMP)Al(iBu)(2)](2)(C5H4)(2)Fe (5). In the absence of Lewis donating cosolvents, a 4-fold excess of the sodium zincate appears to produce an unprecedented 4-fold zincated ferrocene of formula Na-4(TMP)(4)Zn-4(tBu)(4)[(C5H3)(2)Fe] (3), whereas when donor solvent is withheld from the lithium/aluminum 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 toward lithium, preventing inverse-crown formation and preferentially forming the Lewis add Lewis base adduct [TMP(H)center dot Li(mu-TMP)Al(iBu)(2)](2)(C5H4)(2)Fe (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.