Original scientific paper

Synthesis and Structure of Geometric Isomers of 1-[(methoxyimino)ethyl]-ferrocene and Methyl 1'-[(methoxyimino)ethyl]ferrocene-1-carboxylate

Mojca Čakić Semenčić ; Department of Chemistry and Biochemistry, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, HR-10000 Zagreb, Croatia
Gordana Pavlović orcid.org/0000-0002-2317-3348 ; Department of Applied Chemistry, Faculty of Textile Technology, University of Zagreb, Prilaz baruna Filipovića 28a, HR-10000 Zagreb, Croatia
Dubravka Šišak ; ETH- Zürich, Department of Materials, Laboratory for Crystallography, Wolfgang Pauli Strasse 10, CH-8039 Zürich, Switzerland
Vladimir Rapić ; Department of Chemistry and Biochemistry, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, HR-10000 Zagreb, Croatia

Abstract

Here we report synthesis, spectral data and single-crystal X-ray molecular and crystal structures
of (E)-1-[(methoxyimino)ethyl] ferrocene (2) and (E)-methyl 1'-[(methoxyimino)ethyl]ferrocene-1-
carboxylate (4). These organometallics are recognized as precursors for optically pure (1-
ferrocenylethyl)amine (Fea) and 1'-(1-aminoethyl)ferrocene-1-carboxylic acid (Fcca) derivatives. The
(E/Z)mixtures of the title compounds 2 and 4 were obtained in ≈90 % yield by the action of methoxyamine
hydrochloride on acetylferrocene (1) and 1'-acetylferrocene-1-carboxylic acid (3). By means of preparative
thin layer chromatography the synthesized compounds were separated into 75 % of (E)-2 and 15
% of (Z)-2, as well as into 68 % of (E)-4 and 22 % of (Z)-4.
Crystal structures of the dominant isomers of 2 (two molecules within asymmetric unit) and 4 confirm
that both compounds exist in (E)-forms. The ferrocenyl moieties deviate slightly from eclipsed conformation
in 2 and 4. The intramolecular C−H···O contact in the C(CH3)−N−OCH3 group (2.670(7) Å in the
second molecule of 2 and 2.644(6) Å in 4) can be regarded as a weak intramolecular hydrogen bond. The
crystal packings of 2 and 4 are characterized only by van der Waals forces.

Keywords

[(methoxyimino)ethyl]ferrocene derivatives; E/Z isomerism; synthesis; crystal structure

Hrčak ID:

62208

URI

https://hrcak.srce.hr/62208

Publication date:

5.10.2010.

Visits: 2.594 *