Synthesis, Structure, Thermal Properties and Reactivity Studies on Manganese Amidinates and ß-Ketoiminates Supported by DFT: Potential Precursors for Vapor Deposition of Mn-Based Thin Films

To identify Mn based organometallic compounds that serve as precursors for chemical vapor deposition (CVD) and atomic layer deposition (ALD) processes, systematic synthetic approaches with ligand variation, detailed characterization and theoretical input from density functional theory (DFT) studies were adopted. In this context, a series of new homoleptic all-nitrogen and mixed oxygen/nitrogen-coordinated Mn(II) complexes bearing the acetamidinate, formamidinate, guanidinate and ß-ketoiminate ligands have been successfully synthesized for the first time. The compounds were thoroughly characterized by single crystal X-ray diffraction, Evans NMR, mass spectrometry and elemental analysis. To evaluate their potential use as precursors for Mn-based materials, the thermal properties were investigated in detail. The specific choice of these ligand classes with changes in structure and coordination sphere and side chain variations result in significant structural differences whereby mononuclear and dinuclear complexes are formed. This was supported by density functional theory (DFT) studies. The most promising Mn(II) compounds in terms of the thermal properties, namely Bis(N,N´-ditertbutylformamidinato)manganese(II) and Bis(4-(isopropylamino)pent-3-en-2-onato)manganese(II) were used in reactivity studies with DFT to explore their interaction with oxidizing co-reactants such as oxygen and water which are relevant for CVD and ALD process development.