Massive chemical studies on lowcoordinated group 14-16 compounds have been implemented. This thesis focuses particularly on silenes affected by reverse Sid-=Cd+ bond polarization. Hypercoordinated carbon compounds are usually studied.The geometries from calculations with several common computationally inexpensive methods have been tested against top level CCSD/cc-pVTZ geometries for the selection of substituted silenes. Hybrid HF/DFT methods performed best among the list of inexpensive methods tested for silenes.Heavy alkenes strongly affected by reverse polarization are merely to get fewer exothermic dimerization energies for both head-to-head and head-to-tail dimerizations, and also to have higher activation energies for water addition than naturally polarized heavy alkenes.We also investigated solvated lithium, magnesium and potassium silenolates and discovered that lithium and magnesium ions coordinate preferably to O, giving their SiC bond some double bond character.Reverse polarized 2-siloxy-, 2-thiosiloxy-, and 2-(N-sila-N-methyl)-silenes could according to calculations be formed thermolytically from the corresponding tetrasilanes as transient species.
Contents: Lowcoordinated Silicon and Hypercoordinated Carbon: Structure and Stability of Silicon Analogs of Alkenes and Carbon Analogs of Silicates
1. Introduction
2. Bonding Models for Heavy Alkenes
3. Quantum Chemical Methods
3.1 The Hartree-Fock Method
3.2 Configuration Interaction
3.3 The Coupled-Cluster Method
3.4 Many-Body Perturbation Theory
3.5 Density Functional Theory
3.5.1 Exchange-Correlation Functional
3.6 Basis Sets in Ab Initio and DFT Calculations
3.6.1 Effective Core Potentials
3.7 Natural Bond Orbital Analysis
3.7.1 Natural Resonance Theory
4. On the Performance of Inexpensive Quantum Chemical Methods for the Calculation of Geometric Parameters of Silenes
4.1. Different Methods and their Ability to Calculate the Structure of Silenes
4.2 Conclusions
5. The Effect of Reverse Polarization on the Structure and Stability of Heavy Alkene, Imine and Ketone analogs
5.1 Effect of Reverse Polarization on Heavy Alkene Geometries and Charge Distribution
5.2. Effect of Reverse Polarization on the Thermodynamic Stability Towards Dimerization
5.3. Effect of Reverse Polarization on Kinetic and Thermodynamic Stability of Heavy Alkenes toward Addition of Water
6. The Effect of Substituents and Counterions on the Geometry and Electronic Properties of Silenolates
6.1 Analysis of the Uncoordinated Silenolates
6.2 Analysis of the Solvated Metal Silenolates
7. How Reverse Polarization Affects the Reaction Profile for Thermolytic Formation of Silenes
7.1 Effects of Reverse Polarization on Silene Geometries
7.2 Effects of Reverse Polarization on Reaction Profile
8. Substituent Effects on the Retrocyclization Reaction of Silacyclo-but-2-enes to 1-Silabuta-1,3-dienes
9. Hypervalent Carbon Compounds
9.1. Hypervalency…
Lowcoordinated Silicon and Hypercoordinated Carbon: Structure and Stability of Silicon Analogs of Alkenes and Carbon Analogs of Silicates
Source: Uppsala University Library
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