Experimental and theoretical gas phase electronic structure study of tetrakis(dimethylamino) complexes of Ti(IV) and Hf(IV)

Abstract

The gas phase electronic structure of two transition metal alkylamino complexes, M(N(CH3)2)4, where M = Ti, Hf, was studied using photoelectron spectroscopy and density functional theory (DFT). These studies are a first step for predicting atomic layer and chemical vapor deposition reactions on surfaces, which are common applications of these molecules. The valence photoemission spectra of these two complexes were collected with 50 and 150 eV photon energies. Comparison of calculated ionization energies and our experiments yielded good agreement. Analysis of calculated molecular orbitals provides insight into the π-donation interaction between the lone pair of electrons on the amino ligands and the empty metal orbitals. In addition to the valence structure, the core level photoemission spectra were analyzed. The π-interaction was found to influence core level ionization energies. Vibrational structure in the C 1s spectra are reported with insight from DFT calculations. The comprehensive experimental and theoretical characterization of the electronic structure of these complexes provide a robust foundation to progress to detailed spectroscopic studies of the interactions between these molecules and surfaces.