Structure of heteroannularly disubstituted ferrocene derivatives containing acetamido group Mario Cetina, a* Senka Djaković, b Mojca Čakić Semenčić, b and Vladimir Rapić b* a Department of Applied Chemistry, Faculty of Textile Technology, University of Zagreb, Prilaz baruna Filipovića 28a, HR-10000 Zagreb, Croatia b Department of Chemistry and Biochemistry, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, HR-10000 Zagreb, Croatia Corresponding authors: Vladimir Rapić. Tel.: ++385 1 4605 275; Fax: ++385 1 4836 083; e-mail: vrapic@pbf.hr Mario Cetina. Tel.: ++385 1 3712 590; Fax: ++385 1 3712 599; e-mail: mario.cetina@ttf.hr