Heterotrimetallic M−M′−M′′ Transition Metal Complexes Based on 1,3,5-Triethynylbenzene: Synthesis, Solid State Structure, and Electrochemical and UV−Vis Characterization. EPR Analysis of thein SituGenerated Associated Radical Cations

The synthesis of a series of complexes with different organometallic building blocks unsymmetrically arranged around the periphery of a 1,3,5-triethynylbenzene core is discussed. They are accessible by diverse consecutive reaction sequences, which allow the introduction of transition metal units such as Fc, [( t Bu 2 bpy)(CO) 3 Re], [(η 5 -C 5 H 5 )(Ph 3 P) 2 Ru], [(η 5 -C 5 H 5 )(Ph 3 P) 2 Os], and trans -[(Ph 3 P) 2 (Cl)Pt] (Fc = (η 5 -C 5 H 5 )(η 5 -C 5 H 4 )Fe; t Bu 2 bpy = 4,4′-di- tert -butyl-2,2′-bipyridyl). The solid state structures of five complexes have been determined. The electrochemical behavior of the newly synthesized mono-, heterobi-, and heterotrimetallic assemblies have been studied, showing that there is no significant electronic interaction between the respective metal atoms. UV−vis spectroscopic measurements suggest a weak interaction between the appropriate metal atoms. The associated radical cations were in situ generated by stepwise chemical oxidation and characterized by continuous wave electron paramagnetic resonance (EPR) investigations in X-band performed at low temperatures.