1-Ferrocenylmethyl-3-(2,4,6-trimethylbenzyl)-1H-imidazolidin-3-ium iodide and trans-bis(3-benzyl-1-ferrocenylmethyl-1H-imidazolidin-2-ylidene)diiodidopalladium(II)

Acta Cryst. (2012). C68, m48–m52 (http://doi.org/fxzh8t)

N-Heterocyclic carbenes are compatible with most transition metals and generally lead to air-stable and thermally robust complexes that do not undergo ligand dissociation. They have shown great potential in homogeneous catalysis. In this field, we report here the crystal structures of [Fe(C₅H₅)(C₁₉H₂₄N₂)]I, (I), and trans- [Fe₂Pd(C₅H₅)2(C₁₆H₁₇N₂)₂I₂], (II). Compound (I) has two iodide anions and two imidazolidinium cations within the asymmetric unit (Z′ = 2). The two cations have distinctly different conformations, with the ferrocene groups orientated exo and endo with respect to the N-heterocyclic carbene. Compound (I) can be shown to act as an anion receptor and is used in preparing chiral carbene ligands and their complexes. In complex (II), the ferrocenylmethyl group acts as a pendant group on the N atom of imidazolidin-2-ylidene and shows square-planar coordination around the Pd^II metal, which is located on an inversion centre (Z′ = 0.5). The ferrocene and benzyl substituents are in a trans–anti arrangement.