Macrocycles as platforms for mono-and dinuclear calcium chemistry
View/ Open
Appendix.zip (3.370Mb)
Connolly2017.pdf (28.32Mb)
Date
07/07/2017Item status
Restricted AccessEmbargo end date
31/12/2100Author
Connolly, Emma Anne
Metadata
Abstract
This thesis presents the design and structure of a number of Schiff-base
pyrrole macrocycles, their use in the formation of mono- and dinuclear calcium
complexes, and reactions with various alkali- and transition metals to form mixed-metal
clusters.
Chapter One introduces the range of Schiff-base macrocycles with tuneable
properties for various synthetic applications. Previously reported complexes of
various s-, d- and f-block metals in these macrocyclic frameworks are also discussed.
Research into calcium chemistry is reviewed, both in catalysis of synthetic organic
processes, and in synthetic modelling of reaction clusters found in protein structures.
Chapter Two details the synthesis of three monometallic calcium complexes
utilising Schiff base macrocycles H4LEt and H4LA, and dipyrrin ligand HLD. Reactions
of Ca(THF)2(H2LEt) with transition metal halides and amines is outlined, leading to
the formation of M2(LEt) (M = Fe, Co, Cu). Deprotonation of Ca(THF)2(H2LEt) with
alkali metal amines forms calcium-alkali metal complexes; further reactivity of these
with transition metal halides demonstrates unusual stoichiometry in the synthesis of
mixed-metal clusters. Some of these complexes were assessed for catalytic activity in
the hydroamination of isocyanates.
Chapter Three describes the synthesis and characterisation of bimetallic
calcium complexes of the ligands H4LEt, H4LA and H4LS5. Reactions of Ca2(THF)2(μ-
THF)(LEt) with a range of small molecules - including H2O, LiOH and KOH - is
outlined. In particular, reactivity of Ca2(THF)2(μ-THF)(LEt) with NaOH yielded
calcium-alkali metal clusters Ca2(THF)2(μ-OH)(Na{THF}2)(LEt) and Ca2(THF)2(μ-
OH)2(Na{THF})2(LEt), which displayed alternate wedged and bowl-shaped
conformations of the macrocycle ligand. Further homobimetallic complex syntheses
of M2(LEt) (M = Sn, Mn, Sr) are also outlined for comparison to calcium complexes.
Chapter Four presents a summary of the work presented in this thesis, and
Chapter Five outlines the full experimental procedures and analytical data for all
described complexes.