Synthesis and reactivity of a strained silicon-bridged [1]ferrocenophanium ion

Angew Chem Int Ed Engl. 2009;48(27):4961-4. doi: 10.1002/anie.200901213.

Abstract

Not blue but red-brown: A [1]ferrocenophanium ion has been synthesized and isolated as a red-brown crystalline salt, surprisingly different in color from characteristically blue-green unstrained ferrocenium ions. Compared to the neutral iron(II) counterpart, the [1]ferrocenophanium ion displays a considerably higher ring tilt and an increased propensity for ring-opening reactions.