METAL ATOM SYNTHESIS, PROPERTIES, AND STRUCTURE OF MU(2)-(ETA(3),ETA(3)-TOLUENE)BIS[(ETA(6)-TOLUENE)IRON](FE-FE)

Metal atom cocondensation of iron atoms and toluene produces the mononuclear iron sandwich compound [(eta(6)-toluene)(eta(4)-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 degrees C, the proposed intermediates react with toluene to form the first homoleptic Fe/toluene complex mu(2)-(eta(3):eta(3)-toluene)-bis[(eta(6)-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 H-1-, C-13-, and Massbauer spectroscopy as well as by an X-ray structure analysis (-173 degrees C). The X-ray structure determination reveals a mu-eta(3):eta(3)-bridging toluene Ligand capping two ((eta(6)-toluene)Fe) units which are connected by an Fe-Fe bond [2.746(1) Angstrom]. However, in solution up to -30 degrees C all three toluene ligands are fluxional according to H-1- and C-13-NMR data, At -10 degrees 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.