Cleavage of [Pd₂(PP)₂(<i>μ</i>-Cl)₂][BArF₂₄]₂ (PP = Bis(phosphino)ferrocene, BArF₂₄ = Tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) with Monodentate Phosphines

Abstract

The addition of Na[BArF24] (BArF24 = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) to [Pd(PP)Cl2] (PP = 1,1′-bis(phosphino)ferrocene ligands) compounds results in the loss of a chloride ligand and the formation of the dimeric species [Pd2(PP)2(μ-Cl)2][BArF24]2. In most cases, the addition of a monodentate phosphine, PR3, to these dimeric species leads to cleaving of the dimer and formation of [Pd(PP)(PR3)Cl][BArF24]. While these reactions are readily observed via a significant color change, the 31P{1H} NMR spectra offer more significant support, as the singlet for the dimer is replaced with three doublets of doublets. The reaction seems to take place for a wide range of PR3 ligands, although there do appear to be steric limitations to the reaction. The compounds were thoroughly characterized by NMR, and X-ray crystal structures of several of the compounds were obtained. In addition, the ferrocenyl backbone of the 1,1′-bis(phosphino)ferrocene ligands provides an opportunity to examine the oxidative electrochemistry of these compounds. In general, the potential at which oxidations of these compounds occurs shows a dependence on the phosphine substituents.

Keywords

• synthesis
• X-ray crystallography
• cyclic voltammetry
• phosphine
• dimer