Modeling of Transition State in Grignard Reaction of Rigid N-(Aryl)imino-Acenapthenone (Ar-BIAO): An Experimental and Computational Approach

Gupta, S D (2014) Modeling of Transition State in Grignard Reaction of Rigid N-(Aryl)imino-Acenapthenone (Ar-BIAO): An Experimental and Computational Approach. Masters thesis, Indian Institute of Technology, Hyderabad.

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Abstract

In chapter 1, a combined synthetic and computational study has been carried out on the addition of Grignard reagents RMgBr (R = Me, Et) to various sterically rigid N-(Aryl)imino- Acenapthenone (Ar-BIAO) (Ar = 2,6-iPr2C6H4 (1), 2,6-Me2C6H4 (2), 2,4,6-Me3C6H3 (3) ligands. In the experimental method, when the compounds 1-3 were treated with RMgBr (R = Me, Et) in ambient temperature, the corresponding N-(Aryl)imino-Acenaphthylene-1-ol (Ar-BIAOH) (Ar = 2,6- iPr2C6H4; R = Me (1a), Et (1b); Ar = 2,6-Me2C6H4; R = Me (2a), Et (2b) and Ar = 2,4,6- Me3C6H3; R = Me (3a), Et (3b) were obtained in a yield up to 82%. The Ar-BIAOH compounds were characterized by spectroscopic and combustion analyses and the solid state structures of the compounds 1a-3a were established by single crystal X-ray diffraction analysis. To model the transition state of the Grignard reaction with unsymmetrical and sterically rigid Ar-BIAO ligands having three fused rings containing exocyclic carbonyl and imine functionality, we carried out computational analysis. During our study, we have considered the gas phase addition of CH3MgBr to 2 (Scheme a) and the model system of 2-(methylimino)pentanone (2′). We have carried out ab-initio (HF/3-21G(d)) and density functional theory (DFT) calculations with the hybrid density functional B3LYP/6-311+G(2d,p) to probe into two major aspects (i) stability of an intra-molecular chelation involving Magnesium, carbonyl Oxygen and imine Nitrogen (ii) to suggest a probable transition state and mechanistic pathway. The theoretical analysis suggests the formation of tetra-coordinated magnesium complex as the transition state.

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Item Type: Thesis (Masters)
Uncontrolled Keywords: TD164
Subjects: ?? sub5.8 ??
Divisions: Department of Chemistry
Depositing User: Users 4 not found.
Date Deposited: 01 Oct 2014 06:22
Last Modified: 08 Jul 2015 06:56
URI: http://raiith.iith.ac.in/id/eprint/106
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