Synthesis, structure and stereochemistry of diiodide complexes (E)[(η5-t-BuC5H3)Fe(CO)2I]2 (E = Me2Si, Me2SiSiMe2, and Me2SiOSiMe2)

Abstract

Reactions of diiron complexes (E)[η5-t-BuC5H3)Fe(CO)]2(μ-CO)2 [E = Me2Si (1), Me2SiSiMe2 (2), and Me2SiOSiMe2 (3)] with iodine in CHCl3 yielded diiodide complexes (E)[η5-t-BuC5H3)Fe(CO)2I]2 [E=Me2Si (5), Me2SiSiMe2 (6), and Me2SiOSiMe2 (7)]. Like (1–3), complexes (5–7) also exists as mixtures of cis and trans isomers even though the Fe–Fe bond in (1–3) has been cleaved. When the pure isomers (1–3) reacted with iodine respectively in CHCl3, the cis isomers (1c–3c) yielded only the cis products (5c–7c), whereas the trans isomers (1t–3t) yielded only the trans isomers (5t–7t). This indicates that iodination of bridged diiron complexes is stereospecific. Similar treatment of trans-(Me2Si)[{η5-t-(heptyl)C5H3}Fe(CO)]2(μ-CO)2 (4t) with iodine gave only the trans product (Me2Si)[{η5-t-(heptyl)C5H3}Fe(CO)2I]2 (8t). The molecular structure of (5t) was determined by X-ray diffraction.