University of Sussex
Browse
Khalaf,_Majid_Shannon.pdf (2.9 MB)

Coordination chemistry of bicyclic guanidines and guanidinates

Download (2.9 MB)
thesis
posted on 2023-06-07, 16:10 authored by Majid Shannon Khalaf
A [5:5] ligand based on the bicyclic guanidine 1,4,6-triazabicyclo[3.3.0]oct-4-ene [Htbo] has been synthesised. Two of these tbo units have been linked via a carbon bridgehead to form a novel bidentate ligand. Based on the knowledge that the electronic properties and specific steric interactions at a metal can lead to new insights into the relationship between crystal structure and ligand activity, the synthesised compounds have been investigated as polydentate ligands on the assumption that that they could be used to precisely control coordination environment. The corresponding [6:6] system which is based on the bicyclic guanidine 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine) [hppH] has also been synthesised and its coordination to silyl groups investigated. 1,4,6-triazabicyclo[3.3.0]oct-4-ene (Htbo) has been deprotonated to form the [tbo]- anion, which has been assessed as a ligand at Li, Al and Zn centres, allowing direct structural comparison to be made with the [hpp]- analogues. The coordination chemistry of Htbo and its derivatives has been explored through formation of a variety of transition metal complexes. Additionally, crystal structures showed that Htbo coordinates to the metal through the N-imine atom as a monodentate ligand to form trigonal planar, tetrahedral, square planar and octahedral complexes. The bis (tbo) methane H2C{tbo}2 ligand was found to support a range of coordination geometries and upon coordination, ionic structures such as [Pd(H2C{tbo}2)2][Cl]2 were formed. The synthesis of the monosubstituted compound hppSiCl3 afforded a series of (hpp) silanes which were isolated and reacted with LiOAr (Ar= 2,6-tBu2C6H3), providing a proof of N-Si bond stabilisation using a metal. Five examples of pentacoordinated silicon species have been synthesised via the reaction of [hpp]- and R2SiCl2 (R= Ph, Me).

History

File Version

  • Published version

Pages

116.0

Department affiliated with

  • Chemistry Theses

Qualification level

  • doctoral

Qualification name

  • dphil

Language

  • eng

Institution

University of Sussex

Full text available

  • Yes

Legacy Posted Date

2011-09-13

Usage metrics

    University of Sussex (Theses)

    Categories

    No categories selected

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC