Intervalence charge transfer in osmium(IV) tetra(ferrocenylaryl) complexes

Tetra(ferrocenylaryl) complexes comprising Os(IV) or sp3-hybridized C and Si central atoms are prepared through Negishi cross-coupling from brominated precursors and structurally characterized using single-crystal X-ray diffraction. Solution voltammetric studies reveal access to mixed-valence states is uniquely provided by the Os(IV) species, which we show through spectroelectrochemical studies exhibit near-IR features characteristic of intervalence charge transfer processes. Together, this work highlights the potential utility of such metal tetraaryl complexes as building blocks for extended, three-dimensional molecular materials with improved electronic properties.