Designing Volatile Molybdenum Compounds for Vapour-Phase Deposition
type: CreativeWork
description: The vapor phase deposition of many molybdenum-containing films relies on the delivery of volatile compounds with the general bis(tert-butylimido)molybdenum(VI) framework. Herein the preparation and thermal characterization of several adducts of (tBuN)2MoCl2 with various neutral ligands is described. All of the compounds were characterized using NMR and IR spectroscopy, high-resolution mass spectrometry, and elemental analysis, and their solid-state structures have been determined using single-crystal X-ray crystallography. The volatility and thermal stability of all compounds have also been assessed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively. Although many of the compounds described herein are volatile, the focus of this thesis relates to the demystification of their mechanism(s) of thermal decomposition and systematic modifications to increase their thermal stabilities. When weakly coordinating ligands, such as ethers, are used, the ligands dissociate from the metal complex upon heating forming the dimeric compound, [(tBuN)Mo(μ-NtBu)Cl2]2, which has been isolated and characterized in the solid state. Notably, when neutral N,N’-chelating ligands were employed the ligands remained coordinated to the metal complex during its evaporation process. These compounds were found to all undergo analogous decomposition pathways: first the ligands dissociated from the metal complex forming (tBuN)2MoCl2 in the gas phase, which subsequently underwent γ-hydrogen transfer yielding a nitrido-amido adduct (tBuNH)MoNCl2 and isobutylene. Ultimately, the molybdenum species undergoes further decomposition to yield tert-butylamine and Mo2N. The mechanism of thermolysis has been investigated using computational methods, and the computed activation barrier was confirmed using an experimental Eyring analysis. The volatile decomposition products were confirmed using a combination of 1H NMR spectroscopy and gas-chromatography mass spectrome…
abstract: The vapor phase deposition of many molybdenum-containing films relies on the delivery of volatile compounds with the general bis(tert-butylimido)molybdenum(VI) framework. Herein the preparation and thermal characterization of several adducts of (tBuN)2MoCl2 with various neutral ligands is described. All of the compounds were characterized using NMR and IR spectroscopy, high-resolution mass spectrometry, and elemental analysis, and their solid-state structures have been determined using single-crystal X-ray crystallography. The volatility and thermal stability of all compounds have also been assessed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively. Although many of the compounds described herein are volatile, the focus of this thesis relates to the demystification of their mechanism(s) of thermal decomposition and systematic modifications to increase their thermal stabilities. When weakly coordinating ligands, such as ethers, are used, the ligands dissociate from the metal complex upon heating forming the dimeric compound, [(tBuN)Mo(μ-NtBu)Cl2]2, which has been isolated and characterized in the solid state. Notably, when neutral N,N’-chelating ligands were employed the ligands remained coordinated to the metal complex during its evaporation process. These compounds were found to all undergo analogous decomposition pathways: first the ligands dissociated from the metal complex forming (tBuN)2MoCl2 in the gas phase, which subsequently underwent γ-hydrogen transfer yielding a nitrido-amido adduct (tBuNH)MoNCl2 and isobutylene. Ultimately, the molybdenum species undergoes further decomposition to yield tert-butylamine and Mo2N. The mechanism of thermolysis has been investigated using computational methods, and the computed activation barrier was confirmed using an experimental Eyring analysis. The volatile decomposition products were confirmed using a combination of 1H NMR spectroscopy and gas-chromatography mass spectrome…
author: Land, Michael Alexander
language: en
date published: 2023
date modified: 2026-07-24T01:34:41Z
provider: Carleton University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Carleton University

PropertyValue
property ID: Handle
value: https://hdl.handle.net/20.500.14718/42857

PropertyValue
property ID: DOI
value: 10.22215/etd/2023-15461