Theoretical Studies of Photoactive Metal Complexes with Applications in C-H Functionalization and Quantum Computing

• Main Author: Alamo Velazquez, Domllermut C.
• Other Authors: Cundari, Thomas, Valsson, Omar, Wang, Hong, Richmond, Michael, Lee, Wei-Tsung
• Format: Thesis
• Language: English
• Published: University of North Texas 2023
• Subjects: organometallics; qubit; nickel; cobalt; iron; quantum computing; Gaussian; ORCA; photocatalysis; photochemistry; photophysics; C-H activation; excited states; phosphorescence; computational chemistry; Chemistry; Inorganic; Physical; Orca
• Online Access: https://doi.org/10.12794/metadc2137532; https://digital.library.unt.edu/ark:/67531/metadc2137532/

Previous work was successful at delineating reaction pathways for the photoactivated synthesis of an amine, [CztBu(PyriPr)(NH2−PyriPr)], by double intramolecular C−H activation and functionalization via irradiating a metal(II) azido complex, [CztBu(PyriPr)2NiN3. The present work seeks to expand upon earlier research, and to substitute the metal with iron or cobalt, and to expand the study to photocatalyzed intermolecular C−H activation and functionalization of organic substrates. Density functional theory (DFT) – B3LYP/6-31+G(d') and APFD/Def2TZVP – and time-dependent density functional theory (TDDFT) were used to propose a detailed pathway comprised of intermediates of low, intermediate, or high spin multiplicity and photo-generated excited states for the reaction of the azido complex, [CztBu(PyriPr)2MN3] to form the amine complex [CztBu(PyriPr)M(NH2−PyriPr)], M = Co, Ni or Fe, and the intermediates along the reaction pathway. For applications on quantum computing, the photophysical properties of photoactive d8 nickel(II) complexes are modeled. Such systems take advantage of a two-level system pathway between ground to excited state electronic transitions and could be useful for the discovery of successful candidates for a room temperature qubit, the analogue of a classical computational bit. A modified organometallic model, inspired by a nitrogen vacancy selective intersystem crossing model in diamond, was developed to take advantage of the formation of excited states. Tanabe-Sugano diagrams predict areas where these excited states may relax via phosphorescent emission. Under Zeeman splitting, these transitions create the conditions required for a two-level system needed to design a functional organometallic qubit.