Metallatomsynthese, Eigenschaften und Struktur von μ₂‐(η³,η³‐Toluol)bis[(η⁶‐toluol)eisen](Fe‐Fe)

Metal Atom Synthesis, Properties, and Structure of μ₂(η³,η³‐Toluene)bis[(η⁶‐toluene)iron](Fe‐Fe)

Metal atom cocondensation of iron atoms and toluene produces the mononuclear iron sandwich compound [(η⁶‐toluene)(η⁴‐toluene)Fe] 1. Complex 1 reacts with a palette of N‐containing ligands such as primary, secondary, and tertiary amines as well as pyridine, pyrrolidine, and tmeda to form highly reactive instable intermediates. In the temperature range from ‐80 to ‐30°C, the proposed intermediates react with toluene to form the first homoleptic Fe/toluene complex μ₂‐(η³η³‐toluene)‐bis[(η⁶‐toluene)iron](Fe‐Fe) (3) regardless which N‐containing ligand is used. Additionally, 3 is also formed when ethanol is used instead of N‐containing base ligands. Black thermolabile 3 was characterized by low‐temperature ¹H‐, ¹³C‐, and Möβbauer spectroscopy as well as by an X‐ray structure analysis (‐173°C). The X‐ray structure determination reveals a μ‐η³η³‐briding toluene ligand capping two {(η⁶‐toluene)Fe} units which are connected by an Fe‐Fe bond [2.746(1) Å]. However, in solution up to ‐30°C all three toluene ligands are fluxional according to ¹H‐ and ¹³C‐NMR data. At ‐10°C 3 reacts with CO with decomposition to form Fe metal. With 2,2‐bipyridine and ethene no reaction is observed up to room temperature.