Ion-like ethylzinc(II) compounds with weakly coordinating aluminates [Al(OR(F))4](-) and [(R(F)O)3Al-F-Al(OR(F))3](-) (R(F)=C(CF3)3) were synthesized in a one-pot reaction and fully characterized by single-crystal X-ray diffraction, NMR and vibrational spectroscopy, and by quantum chemical calculations. The catalytic activity of ion-like Et-Zn[Al(OR(F))4] in intermolecular hydroamination and in the unusual double hydroamination of anilines and alkynes was investigated. Favorable performance was also found in comparison to the Et2Zn/[PhNMe2H](+)[B(C6F5)4](-) system generated in situ at lower catalyst loadings of 2.5 mol %.
Attempts to prepare previously unknown simple and very Lewis acidic [RZn] [Al(OR ) ] salts from ZnR , AlR , and HO-R delivered the ion-like RZn(Al(OR ) ) (R=Me, Et; R =C(CF ) ) with a coordinated counterion, but never the ionic compound. Increasing the steric bulk in RZn to R=CH CMe , CH SiMe , or Cp*, thus attempting to induce ionization, failed and led only to reaction mixtures including anion decomposition. However, ionization of the ion-like EtZn(Al(OR ) ) compound with arenes yielded the [EtZn(arene) ] [Al(OR ) ] salts with arene=toluene, mesitylene, or o-difluorobenzene (o-DFB)/toluene. In contrast to the ion-like EtZn(η -C H )(CHB Cl ), which co-crystallizes with one benzene molecule, the less coordinating nature of the [Al(OR ) ] anion allowed the ionization and preparation of the purely organometallic [EtZn(arene) ] cation. These stable materials have further applications as, for example, initiators of isobutene polymerization. DFT calculations to compare the Lewis acidities of the zinc cations to those of a large number of organometallic cations were performed on the basis of fluoride ion affinity. The complexation energetics of EtZn with arenes and THF was assessed and related to the experiments.
We describe synthesis routes from fluorinated ethylzinc alkoxides to ether adducts of fluorinated binary homoleptic zinc alkoxides with fluorinated residues such as ORF (OC(CF3)3), ORHF (OC(H)(CF3)2), ORHT (OC(CH3)(CF3)2), ORAF (perfluoroadamantoxy) and ORCY (OC(CF3)(CF2)5). Their structures depend on the nature of the fluorinated residue: perfluorinated alkoxides ORXF tend to give monomeric ether adducts (ether)2Zn(ORXF)2, while partially fluorinated residues ORYF lead to dimers of type (ether)(YFRO)Zn(μ‐ORYF)2Zn(ORYF)(ether). The monomeric (Et2O)2Zn(ORF)2 was tested for its possibility to form fluorine doped zinc oxide upon thermal decomposition in inert atmosphere. Indeed, upon thermal degradation, homogenously doped materials (EDX mapping) with fluoride contents of 5.5 to 6 weight‐% form (EDX, ion chromatography).
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