The synthesis and characterization of five new and closely related homoleptic iron(II) -ketoiminate complexes is reported. Molecular structures of compounds 1, 2, and 5 were determined by single-crystal XRD, which revealed monomeric four-and sixfold coordination, depending on the functionalized side chain. The stepwise elimination of the ligand from the complex observed by thermogravimetric analysis and the stability in solution are encouraging features for solution-based [a] 1824 processing of hematite thin films. As a representative example, compound 1 was successfully employed in a straightforward spin-coating process. The fabricated iron oxide films were characterized in terms of their structure and phase by XRD and Raman spectroscopy, morphology by SEM, and composition by Rutherford backscattering spectrometry accompanied by nuclear reaction analysis, which revealed the formation of crystalline and stoichiometric α-Fe 2 O 3 films. sition (CSD) techniques of iron oxides such as spin coating, [12] sol-gel processes, [13] and spray pyrolysis [14,15] are of particular interest due to their simple and cost-efficient setup, easy scaleup, and ambient processing conditions. [16] Ideally, precursors for CSD should combine specific characteristics such as high solubility and stability in organic solvents, nontoxicity, and a good compromise between stability to handling in ambient atmosphere and hydrolysis (reactivity) that can enable easy cleavage of ligands to obtain high-purity films on processing. Commonly used iron precursors for CSD of iron oxide are FeCl 2 , [7] FeCl 3 , [14,17] Fe(NO 3 ) 3 , [18,19] and [Fe 4 (mdea) 6 ·6CHCl 3 ]. [20] However, most of these compounds do not feature high solubility and stability in solution, and thus necessitate the use of additives such as amines or long-chain alcohols to enhance the solubility and stabilize the solution. [19,21] Metal alkoxides, for example, [Fe(OtBu) 3 ] 2 , are stable in solution but prone to hydrolysis on exposure to ambient conditions. [22] In the search for suitable precursors for CSD of iron oxide thin films under ambient conditions, the class of metal -ketoiminates is a potential candidate. This ligand class, which has already been successfully applied in metal oxide and nitride CVD and atomic layer deposition (ALD) processes involving metals such as Fe, Zr, Pd, Ga, Ir, Ti, Nb, Ta, and Zn,[23][24][25] features both oxygen and nitrogen coordination, which is a compromise between the highly reactive and thermally unstable nitrogen-bonded metal -diketiminates and the highly stable oxygen-coordinated metal -diketonates. As recently demonstrated by us, iron(II) -ketoiminates are highly promising for gas-phase deposition of iron oxide nanostructures via both ALD and CVD routes at low temperatures. [26] Our next goal was to evaluate this class of compounds for a simple and cost-effective CSD process for iron oxide thin films. As mentioned above, CSD requires precursors with suitable characteristics. The advantageous properties associated with Eur.
