Investigations of Ruthenium (II) Sources for the Synthesis of Ruthenocene and [1.1]Ferro-Ruthenocenophane

Abstract

In order to find alternate sources of rathenium(II) in which the metal is coordinated to easily removed ligands and which would be useful in the synthesis of [1.1]metallocenophanes, a number of candidate Ru(II) compounds were examined for the preparation of ruthenocene. In general, the “Ru[II]” compounds were prepared by methanol reduction (without hydrogen) and are known to be more complicated complexes.

These compounds were as follows: RuCl₂ in THF, RuCl₂ in ethylene glycol diethyl ether (DEE), dibenzeneruthenium(II) hexafluorophophosphate, ruthenium(II) chloride tris-(tri-phenylstibine), and di-μ.-chloro-bis-(benzene-chlororutheni-um(II)]. RuCl₂·3(Ph₃Sb) produced ruthenocene yields of 75% for. It was selected for the synthesis of [l.l] ferro-ruthenocenophane from l,l′-bis-(6-fulvenyl)ferrocene with the best yields (15%) ever reported.

The use of [(Et₂S)₃RuCl₃) with in-situ reducing agents lead to the same [l.l]metallocenophane, but in slightly lower yields (11%). However, a number of attempts to prepare [l.l] ruthenocenophane using either of these two complexes were not succcessful.