Trimetallic complexes featuring Group 10 tetracyanometallate dianions as bridging ligands

• Published in: Inorganica Chimica Acta Vol. 359; no. 11; pp. 3459 - 3466
• Main Authors: Cordiner, Richard L., Feroze, Matthew P., Lledó-Fernandez, Carlos, Albesa-Jové, David, Howard, Judith A.K., Low, Paul J.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2006
• Subjects: Cyanide; Metal–metal interactions; Spectroelectrochemistry; Cyanide; Spectroelectrochemistry; Metal–metal interactions
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2005.10.001

The tetracyanometallate dianions [M(CN) 4] 2− (M = Ni, Pd, Pt) react readily with RuClL 2Cp′ (L = PPh 3, Cp′ = Cp; L 2 = dppe, Cp′ = Cp*) to give trimetallic complexes. The mixed-valence cations generated by one-electron oxidation of these trimetallic complexes are of the Class II variety, with the reorganisation energy associated with the charge transfer process being a major contribution to the IVCT process. The trimetallic complexes {Ru(PPh 3) 2Cp} 2{μ-M(CN) 4} and {Ru(dppe)Cp*} 2{μ-M(CN) 4} (M = Ni, Pd, Pt) have been prepared from reactions of RuCl(PPh 3) 2Cp 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{μ-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.