Trimetallic complexes featuring Group 10 tetracyanometallate dianions as bridging ligands

The trimetallic complexes {Ru(PPh3)(2)CP}(2){mu-M(CN)(4)} and {Ru(dppe)Cp*}(2){mu-M(CN)(4)} (M = Ni, Pd, Pt) have been prepared from reactions of RuCl(PPh3)(2)CP or RuCl(dppe)Cp* with the appropriate tetracyanometallate salt, and structurally characterised. While a similar reaction of FeCl(dppe)Cp with K-2[Pt(CN)(4)] afforded {Fe(dppe)CP}(2){mu-Pt(CN)(4)}, the iron cyanide complex Fe(CN)(dppe)Cp was isolated as the only iron containing product from reaction of FeCl(dppe)Cp with K-2[Ni(CN)(4)]. The trimetallic complexes can be oxidised in two sequential one-electron steps. Spectroelectrochemical experiments reveal weak NIR absorption bands in the mono-oxidised complexes which are not present in the binuclear complex K[Ru(dppe)Cp*{Pt(CN)(4)}], and are therefore attributed to Ru-II -> Ru-III charge transfer processes. The coupling parameter, V-ab, extracted using Hush-style analysis falls in the range 250 +/- 50 cm(-1), consistent with the weak interaction between the Group 8 metal centres. The energy of the IVCT process is dominated by reorganisation energy of the Group 8 metal-ligand fragment. (c) 2005 Elsevier B.V. All rights reserved.