[Bis(trimethylsilyl)amido](η⁵-pentamethylcyclopentadienyl)- iron(II):  A Diamagnetic 14-Electron Complex with a “Pogo-Stick” Structure

Abstract

The half-sandwich complex Cp*FeN(SiMe3)2 was synthesized by the reaction of iron(II) chloride in THF with 1 equiv of KN(SiMe3)2 and subsequent addition of Cp*Li and was structurally characterized by X-ray diffraction; its “pogo-stick” structure is unprecedented in the chemistry of open-shell organometallics.

Iron(II) High‐Spin and Low‐Spin Complexes from Pentaisopropylcyclopentadienyliron(II) Bis(trimethylsilyl)amide

“…This kind of disorder has been found for all four pentaisopropylcyclopentadienyl complexes, the crystal structures of which have been described in this manuscript. The 5 Cp cent –Fe distance of 192.4 pm is only slightly longer than the 190.3 pm reported for the C 5 Me 5 derivative 2 . The same holds for the Fe–N distance of 192.0 pm for 5 compared to 190.0 pm for 2 .…”

“…The 5 Cp cent –Fe distance of 192.4 pm is only slightly longer than the 190.3 pm reported for the C 5 Me 5 derivative 2 . The same holds for the Fe–N distance of 192.0 pm for 5 compared to 190.0 pm for 2 . The closest methyl ··· methyl contacts between silyl groups and 5 Cp in 5 are 353 and 361 pm.…”

“…Two versatile pentamethylcyclopentadienyliron(II) half‐sandwich starting compounds are the Jonas complex [Cp*FeCl(tmeda)] ( 1 ; tmeda = tetramethylethylenediamine) and the Siemeling “pogo‐stick” complex [Cp*FeN(SiMe 3 ) 2 ] ( 2 ) . The absence of strongly bound π‐acceptor ligands like carbon monoxide, the removal of which often requires photochemical or thermal activation, is an advantage especially in combination with enough thermal stability for convenient storage in the laboratory.…”

The Mechanism of N–N Double Bond Cleavage by an Iron(II) Hydride Complex

“…The Fe-N(imido) bond lengths of 1.878(1) and 1.911(1) Å indicate Fe-N single bonds, as they are within the range of crystallographically characterized, low-coordinate Fe-N(amido) bond distances of 1.84(2) to 1.938(2) Å. 24 …”

Structure and Reactivity of Coordinatively Unsaturated Half‐Sandwich Iron, Ruthenium and Osmium Complexes

“…[18] Notably, the diamagnetic 14-electron complex [Cp* Fe{N(SiMe 3 ) 2 }] has been reported. [20] This compound, prepared by reaction of FeCl 2 with one equivalent of K[N(SiMe 3 ) 2 ] in THF and subsequent addition of LiCp*, has a ''pogo-stick'' structure unprecedented in the chemistry of open shell organometallics (Figure 1). …”