| Abstract
| - A new chiral tridentate C2-symmetric ligand containing a carbene and two phosphorus donor atoms and incorporating two ferrocenyl units has been prepared. Pd(II) and Ru(II) complexes of this ligand show its ability to assume both an equatorial and a facial coordination geometry.
- The new chiral imidazolium salt 1,3-bis[(R)-1-((S)-2-diphenylphosphinoferrocenyl)ethyl]imidazolium iodide (4, (PCPH)I) was prepared in three steps from commercially availableN,N-dimethyl-1-ferrocenylethylamine (1) in 55% overall yield. Salt 4 is the precursor forthe in situ generation of a novel tridentate carbene ligand that could not be isolated upondeprotonation of 4 with NaOtBu. Reaction of 4 with [Pd(OAc)2]3 afforded (SP-4)-1,3-bis[(R)-1-((S)-2-diphenylphosphino-κP-ferrocenyl)ethyl]imidazol-2-ylideneiodopalladium(II) acetate,[PdI(PCP)]OAc (6). Treatment of 4 with NaOtBu and [RuCl2(PPh3)3] gave the mixed halidecomplex (SP-5)-1,3-bis[(R)-1-((S)-2-diphenylphosphino-κP-ferrocenyl)ethyl]imidazol-2-ylidenechloroiodoruthenium(II) [RuClI(PCP)] (7a), as a mixture of two isomers in 60% yield.Additional complexes that could be obtained from 4 are [PdCl(PCP)]PF6 (5), [RuCl2(PCP)](7b), and [RuI(PCP)(NCCH3)2]PF6 (8). The crystal and molecular structures of 5 and 7awere determined by X-ray diffraction. The Ru(II) center undergoes a weak agostic interactionwith one of the two stereogenic methine units.
|
