Subvalent Iridium Precursors for Atom-Efficient Chemical Vapor Deposition of Ir and IrO2 Thin Films

A new heteroleptic Ir(I) compound exhibiting high volatility and defined thermal decomposition under CVD conditions is reported. The new iridium precursor [(COD)Ir(ThTFP)] (COD = cyclooctadiene, ThTFP = (Z)-3,3,3-trifluoro-1-(thiazol-2-yl)prop-1-en-2-olate) unifies both reactivity and sufficient stability through its heteroleptic constitution to provide a precise control over compositional purity in CVD deposits. The solution integrity of the monomeric Ir(I) complex was investigated by 1D and 2D NMR spectroscopy and EI mass spectrometry, whereas the molecular structure was confirmed by single-crystal diffraction. CVD experiments demonstrated the suitability of the iridium compound for an atom-efficient (high molecule-to-precursor yield) gas-phase deposition of nanocrystalline iridium films that could be converted into crystalline iridium dioxide upon heat treatment to demonstrate their electrocatalytic potential in the oxygen evolution reaction.