Synthesis, structure and spectroelectrochemical property of (2,2′-bipyridine)–metal (M = Pt, Pd) dichloride with 4,4′-bis(fluorous-ponytail) on bipyridine

The 4,4′-bis(RfCH2OCH2)-2,2′-bpy ligands [Rf = n-C3F7 (1a), HCF2(CF2)3 (1b)] were prepared and then treated with [MCl2(CH3CN)2] (M = Pt or Pd) to result in the corresponding metal complexes, [MCl2(4,4′-bis(RfCH2OCH2)-2,2′-bpy)] (M = Pt 2a–b; Pd 3a–b). Both ligands and metal complexes were fully characterized by multi-nuclei NMR (1H, 19F and 13C), FTIR, and mass (GC/MS or HR-FAB) methods. The X-ray structures of 2a–b and 3a–b were studied. With terminal CF3, the structures of 2a and 3a exhibit disordered polyfluorinated regions in solid state. With terminal HCF2, the structures of 2b and 3b show a π–π stacking of the bpy planes, five-membered C–H···O hydrogen bond and an unusual intramolecular blue-shifting C–H···F–C hydrogen bond system, whereas without terminal HCF2, the structures of 2a and 3a show the similar π–π stacking, five-membered C–H···O hydrogen bond and typical orientation of polyfluorinated ponytails, but not the C–H···F–C hydrogen bond system. The CV and UV/Vis studies were also carried out.

X-ray structures of 2a–b and 3a–b were studied. With terminal HCF2, structures of 2b and 3b show a π–π stacking of bpy planes, five-membered C–H···O hydrogen bond and an unusual intramolecular C–H···F–C hydrogen bond which includes contraction of C–H bond and short H···F distance. Additionally, spectroelectrochemical studies were carried out.Figure optionsDownload as PowerPoint slide