Compounds containing weak, non-covalent interactions to the metal in the backbone of 1,1′-bis(phosphino)metallocene ligands

• Published in: Polyhedron 2016-08, Vol.114, p.156-164
• Main Authors: Warnick, Eugene P., Dupuis, Ryan J., Piro, Nicholas A., Scott Kassel, W., Nataro, Chip
• Format: Article
• Language: English
• Subjects: Chloride-bridged dimer; Cyclic voltammetry; Halide abstraction; Weak non-covalent interaction; X-ray crystal structure
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2015.11.025

Dimers containing 1,1′-bis(diphenylphosphino)metallocene (dppMc) ligands with the formula [Pd(dppMc)(μ-Cl)]2+2 (dppMc=dppr, dppo) were prepared and structurally characterized. Compounds [M(dppMc)PPh3]2+ (M=Pd, dppMc=dppo; M=Pt, dppMc=dppf, dppo) containing an interaction between M and the metal of the dppMc ligand were prepared and structurally characterized. [Display omitted] The reactions of Na[BArF] (BArF=tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) with a series of [Pd(dpEMc)Cl2] (dpEMc=1,1′-bis(diphenylphosphino)ruthenocene (dppr), 1,1′-bis(diphenylphosphino)osmocene (dppo) or 1,1′-bis(diphenylarsino)ferrocene (dpaf)) compounds were examined. The reaction of Na[BArF] with [Pd(dppMc)Cl2] (dppMc=dppr or dppo) resulted in the formation of the corresponding chloride-bridged dimers, [Pd(dppMc)(μ-Cl)]22+, which were structurally characterized. However, these dimers appear to be unstable in CH2Cl2 and partially (Ru) or fully (Os) convert into the corresponding monomers, [Pd(dppMc)Cl]+, which are proposed to have a weak, non-covalent M–Pd (M=Ru or Os) interaction. Similar compounds, [Pd(dppo)PPh3]2+ and [Pt(dppMc)PPh3]2+ (M=Fe (1,1′-bis(diphenylphosphino)ferrocene (dppf)) or Os (dppo)), were also prepared and structurally characterized. These compound also exhibit weak, non-covalent M–Pd/Pt interactions. In addition, the electrochemical properties of these compounds were examined by cyclic voltammetry.