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Title: Targeted synthesis of heterometallic arrangements
Author: Harmer, C.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 1998
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Abstract:
This thesis concerns the investigation of a number of routes to the synthesis of novel heterometallic arrangements containing antimony. The initial aim was to investigate the potential ligand chemistry of the imido Sb(III) anions, [Sb(NR)3]3- - "the trianion". [Sb2(NR)4]2- - "the dianion", and [{(Me2N)Sb(μ-NR)2}2Sb]- - " monoanion", with a view to the incorporation of other metals into their p-block frameworks. Chapter 1 provides a brief overview of the general properties and organometallic chemistry of the p-block and then surveys the chemistry and reactivity of Group 13 and 14 complexes. It goes on to look at the chemistry of Group 15 and introduces the use of p-block dimethylamines [E(NMe2)3 {E = Sb, Bi}] as the basis of the work in this thesis. Chapter 2 introduces the experimental techniques involved in the work and details the synthesis and analysis of the compounds made. Chapter 3 presents a study of the bonding and structure of different trianions with the dual aim of synthesising a range of multifunctional anion ligands. This investigation centres on the syntheses of three imido Sb(III) anions, [{Sb(NCy)3}2Li6.2HNMe2].2toluene (3a), [(Sb{N(2,4-dmp)}3)2Li6.2THF].2toluene (3b) and [{Sb(NtBu)3}2Li6] (3c). It concludes that the Group 15 trianion units dominate these arrangements and that the [N6Li6] subunits perform an associative role. Chapter 4 details the further investigation of transmetallation reactions of the imido Sb(III) anions with a range of metal salts. The rigidity of these ligand systems and their application to the preparation of mixed-metal cages is illustrated by the syntheses and structures of the new cage complexes [Sb(NCy)4(HNCy)2]K.2toluene (4a), containing an early main group metal, [Sb2(NCy)4]2Ag4 (4b), containing a transition metal, and [Sb(NCy)3]2Pb3 (4c), containing a p-block metal. In Chapter 5 we see the extension of the imido Sb(III) anion work to the inclusion of phosphorus in the ligand framework. The stoichiometric assembly of the complex [Sb(PCy)3]2Li6.6HNMe2.2toluene (5a) creates a softer ligand set and a greater ligand bite than the imido congeners and has the potential to allow the stabilisation of low oxidation state transition metal centres. The discovery that thermolysis of 5a at 30°C gives the Zintl compound [Sb7Li3.6HNMe2] (5b) and, with TMEDA, [{(TMEDA)Li}3Sb7] (5c), provides an interesting study, as these complexes could be used in the manufacture of photodiodes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.603724  DOI: Not available
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