Visible-light photolytic synthesis of multinuclear and dendritic iron-nitrile cationic complexes

Multinuclear and dendritic iron-nitrile piano-stool cationic complexes were synthesized in quantitative yield by a single-step synthesis involving visible-light photolysis of the complex [CpFe(eta(6)-toluene)][PF6]. This synthetic strategy was applied to mono-, bis- and tris-nitrile ligands and to new nitrile-terminated dendrimers containing 9, 27, and 81 tethers. All the synthesized products are deep red solids or red Waxy products, highly stable to air and moisture. They were characterized by H-1, C-13, and P-31 NMR, elemental analysis, UV-vis spectroscopy, and cyclic voltammetry (single reversible oxidation wave to Fe-III). Only the. para-disubstituted arene dinitrile diiron complex shows two separated reversible waves indicating some electronic communication between the iron centers through the nitrile ligands.