Jj. Schneider et al., METAL ATOM SYNTHESIS, PROPERTIES, AND STR UCTURE OF 3),ETA(3)-TOLUENE)BIS[(ETA(6)-TOLUENE)IRON](FE-FE), Chemische Berichte, 128(9), 1995, pp. 941-945
Metal atom cocondensation of iron atoms and toluene produces the monon
uclear iron sandwich compound [(eta(6)-toluene)(eta(4)-toluene)Fe] 1.
Complex 1 reacts with a palette of N-containing ligands such as primar
y, secondary, and tertiary amines as well as pyridine, pyrrolidine, an
d tmeda to form highly reactive instable intermediates. In the tempera
ture range from -80 to -30 degrees C, the proposed intermediates react
with toluene to form the first homoleptic Fe/toluene complex -(eta(3)
:eta(3)-toluene)-bis[(eta(6)-toluene)iron] (Fe-Fe) (3) regardless whic
h N-containing ligand is used. Additionally, 3 is also formed when eth
anol is used instead of N-containing base ligands. Black thermolabile
3 was characterized by low-temperature H-1-, C-13-, and Massbauer spec
troscopy as well as by an X-ray structure analysis (-173 degrees C). T
he X-ray structure determination reveals a mu-eta(3):eta(3)-bridging t
oluene Ligand capping two ((eta(6)-toluene)Fe) units which are connect
ed by an Fe-Fe bond [2.746(1) Angstrom]. However, in solution up to -3
0 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 decompositio
n to form Fe metal. With 2,2-bipyridine and ethene no reaction is obse
rved up to room temperature.