Coordination Chemistry in Thin Polymeric Films of poly-[Fe(vbpy)2(CN)2],poly-vbpy. Binding and Reduction of [Rh(COD)Cl] and PdCl2

Thin polymeric films of poly-[Fe(vbpy) 2 (CN) 2 ],poly-vbpy (vbpy is 4-methyl-4‘-vinyl-2,2‘-bipyridine) undergo reactions with transition-metal compounds via the cyano groups or the uncoordinated vinyl-2,2‘-bipyridine. The reaction between the dicyano/vbpy film and [Rh(COD)Cl] 2 led to the incorporation of one or two [Rh(COD)Cl] units into the film. Short reaction periods, <0.5 h, led to the incorporation of one [Rh(COD)Cl] unit by binding to the uncoordinated vbpy group to give poly-[Fe(vbpy) 2 (CN) 2 ],poly-[Rh(vbpy)(COD)]Cl, a second group is incorporated at >0.5 h by binding to one of the cyano groups to give poly-{Fe(vbpy) 2 (CN)[CNRh(COD)Cl]},poly-[Rh(vbpy)(COD)Cl]Cl. Binding sites and compositions within the films were established by FTIR, UV−visible, and XPS measurements. The dicyano/vbpy films also react with PdCl 2 (PhCN) 2 (PhCN = benzonitrile) incorporating two [PdCl 2 ] units to give poly-{Fe(vbpy) 2 (CN)[CNPdCl 2 (NCCH 3 )]},poly-Pd(vbpy)Cl 2 . PdCl 2 incorporation is more rapid than [Rh(COD)Cl]. Electrochemical reduction of films containing Rh I or Pd II resulted in the production of Rh 0 or Pd 0 particles in/on the films. Reduction of a poly-{Fe(vbpy) 2 (CN)[CNPdCl 2 (NCCH 3 )]},poly-Pd(vbpy)Cl 2 film with PdCl 2 (PhCN) 2 in the external solution led to the of dispersion of Pd 0 particles on the film surface as shown by SEM measurements. Films with surface-dispersed palladium or rhodium are active electrocatalysts for the reduction of carbon dioxide.