N: synthesis and electrochemistry-Heterocyclic carbene complexes of palladium(II) and rhodium(I) with pendant ferrocenylmethyl groups: synthesis and electrochemistry
1-Ferrocenylmethyl-3-benzylimidazolidinium iodide and 1-ferrocenylmethyl-3-(2,4,6-trimethylbenzyl)imi-dazolidinium iodide were prepared in good yields by boiling, under reflux, a solution of (ferrocenylmethyl)- trimethylammonium iodide and the appropriate N-alkyl-2-imidazoline in MeCN. From the 1-ferrocenylmethyl-3-ben- zylimidazolidinium iodide salt, N-heterocylic carbene complexes of PdII and RhI were synthesized by in situ deprotonation and subsequent trapping. The new compounds were characterized by C, H, N analyses, 1H-n.m.r., 13C-n.m.r. and by cyclic voltammetry. The n.m.r. properties of the complexes are compared with those of non-ferrocenylated carbene derivatives. The c.v.'s of these compounds show a number of resolved redox processes, indicating that CH2Fc substituents are electronically isolated from the remaining molecular framework.