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-me tal compounds via the cyano groups or the uncoordinated vinyl-2,2'-bip yridine. 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 fi lm. Short reaction periods, <0.5 h, led to the incorporation of one [R h(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 incorp orated at >0.5 h by binding to one of the cyano groups to give poly-{F e-(vbpy)(2) (CN)[CNRh(COD)Cl]},poly-[Rh(vbpy)(COD)Cl]Cl. Binding sites and compositions within the films were established by FTIR, UV-visibl e, and XPS measurements. The dicyano/vbpy films also react with PdCl2( PhCN)(2) (PhCN = benzonitrile) incorporating two [PdCl2] units to give e(vbpy)(2)(CN)[CNPdCl2(NCCH3)]},poly-Pd(vbpy)Cl-2. PdCl2 incorporatio n is more rapid than [Rh(COD)Cl]. Electrochemical reduction of films c ontaining Rh-I or Pd-II resulted in the production of Rh-0 or Pd-0 par ticles in/on the films. Reduction of a Fe(vbpy)(2)(CN)[CNPdCl2(NCCH3)] },poly-Pd(vbpy)Cl-2 film with PdCl2(PhCN)(2) in the external solution led to the of dispersion of Pd-0 particles on the film surface as show n by SEM measurements. Films with surface-dispersed palladium or rhodi um are active electrocatalysts for the reduction of carbon dioxide.