Studies of Metalloporphyrins and Tantalum Amide Imide Compounds

The focus of this dissertation is on two different subjects. The first examines the magnetic and structural properties of metalloporphyrins. In these studies, neutrons were used to probe the magnetic properties of metalloporphyrins. Insight on the structural properties of metalloporphyrins was also gained by examining the intermolecular interactions in the solid state. The second subject is the synthesis and characterization of new tantalum complexes and studies of their reactions with O₂ [dioxygen]. These complexes are potential precursors to make metal oxide and metal nitride thin films.

In the first part of this dissertation, the zero-field parameters D have been directly determined for [M(TPP)Cl] (M = Cr, Mn, Fe, TPP = meso-tetraphenylporphyrinate) and [Mn(TPP)] using inelastic neutron scattering (INS). Non-deuterated samples were used to measure small energy differences of the magnetic excitations in these metalloporphyrins. To our knowledge, this is the first time INS has been used to probe the magnetic excitations in bioinorganic complexes.

Intermolecular interactions in the solid state structures of biomimetic [Fe(TPP)Cl] and [M(TPP)NO] (M = Fe, Co) have been studied using Hirshfeld surface analysis. It was revealed that intermolecular interactions are a significant factor in structure disorders in the three metalloporphyrins and phase changes in the nitrosyl complexes. At the phase change a significant void volume increase was gained by the gradual tilting of phenyl rings, enabling further thermal compression at low temperatures.

In the second half of this dissertation, mixed amide imide alkyl complexes TaR₂(=NSiMe₃)[N(SiMe₃)₂] [tantalum alkyl amide imide] (R = Me or CH₂Ph [benzyl]) have been synthesized and characterized. Their reactions with O₂ [dioxygen] have also been probed, revealing the unique nature of these reactions. Crystal structures of Ta(CH₂Ph)₂(=NSiMe₃)[N(SiMe₃)₂] [tantalum benzyl amide imide] and the methoxy dimer Ta₂(μ-OMe)₂(=NSiMe₃)₂[N(SiMe₃)₂]₂Me₂ [tantalum amide imide methyl methoxy dimer] have been solved and are discussed.

The mixed amide imide complexes Ta(NR₂)(=NSiMe₃)[N(SiMe₃)₂] [tantalum amide imide] (R = Me or Et) have been synthesized from two different starting materials and characterized. One of the reactions involves a rare intramolecular imidation between two amide ligands. The intramolecular imidation has been studied further to gain an understanding of its mechanism.