Abstract
Combining a phosphinoferrocene fragment with extended muItidonor moieties affords novel, flexible muftidonor pro-ligands. This contribution describes the synthesis of two structurally similar functional phosphines, Ph2PfcNHC(O)CH2PPh2 (1) and Ph2PfcNHCH2CH2PPh2 (2, fc = ferrocene-1,1'-diyl), and their coordination behaviour towards Pd(II).
The former amidophosphine reacts with [PdCl2(MeCN)2] to produce the cheIate complex [PdCl2(1-κ(2)P,P')] as a mixture of cis and trans isomers, which convert into bis-cheIate [PdCl2(Ph2PfcNC(O)CH2PPh2-κ(3)P,P',N)] upon reacting with a strong base (KOt-Bu). In contrast, the more flexible and more basic phosphinoamine 2 directly forms the cationic bis-cheIate complex [PdCl(2-κ(3)P,P',N)]CI via spontaneous self-ionisation.
Subsequent halogen abstraction with Ag[SbF6] results either in counter ion exchange to give [PdCl(2-κ(3)Fe,P',P')][SbF6] or in the formation of a structurally unique complex [PdCl(2-κ(4)Fe,P,P', N)][SbF6](2) with an Fe -> Pd dative interaction, depending on the amount of silver(I) salt used (1 or 2 equiv.).