First C4 bridged mixed-valence iron(II)–iron(III) complex delocalized on the infrared timescale

Abstract

The first 35-electron acetylide bridged diiron complex [{Fe(η⁵-C₅Me₅)(dppe)}₂(µ-C₄)]PF₆, 3PF₆[dppe = ethylenebis(diphenylphosphine)] and the 36- and 34-electron bis-iron(II) and bis-iron(III) homologous derivatives are synthesized and it is established that the Fe^II–Fe^III complex is the first non-trapped mixed-valence compound with two half-sandwich monomeric units joined by a C₄ bridge.