Synthesis and Electrochemistry of ((Diferrocenylsilyl)propyl)- and ((Triferrocenylsilyl)propyl)triethoxysilanes

Triferrocenylsilane 2 was synthesized. Hydrosilylation reactions employing allyltriethoxysilane
and diferrocenylmethylsilane (1) and triferrocenylsilane
(2) yielded new ferrocenyltriethoxysilane compounds functionalized
with two (3) and three (4) interacting ferrocenyl
units, respectively. Characterization of 2 and the ethoxysilane
derivatives 3 and 4 by elemental analysis, 1H, 13C­{1H}, and 29Si­{1H} NMR spectroscopy, and mass spectrometry supports their
assigned structures. The crystal structure of 2 has been
determined by a single-crystal X-ray diffraction study. The redox
activity of the ferrocenyl centers in 2–4 has been characterized by cyclic voltammetry and square
wave voltammetry in dichloromethane containing [n-Bu4N]­[PF6] or [n-Bu4N]­[B­(C6F5)4] as electrolyte support.
Voltammetric studies of 2–4 in solution
exhibit the pattern of communicating ferrocenyl sites with two or
three distinct, separated oxidation waves. Platinum oxide surfaces
are covalently modified by redox-active 3 and 4.