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Title: A study of the organometallic chemistry of aluminium, gallium and indium
Author: Phillips, Paul Richard
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 1996
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This thesis describes a study of several aspects of the organometallic chemistry of aluminium, gallium and indium. A study has been carried out on the products obtained from the reactions of trimethyl- and triethyl-metal derivatives of aluminium, gallium and indium with amidines. The compounds [~M(L)] [L = amidinato (R'NCR''NR'); R' = aryl; R" = H, Me, Ph], [RM(PhNCR"NPh)2]' and [M(PhNCR"NPh)3](M = Al, R = Me; M = Ga, In; R = Me, Et; R" = Me, Ph) have been isolated from the reactions of the appropriate trialkyl-metal derivative with 1, 2 and 3 moles of amidine [R'N(H)CR''NR'] respectively. The compounds have been fully characterised, and mass spectroscopic data indicate that the compounds exist as monomers in the gas phase. An X-ray crystallographic study was carried out on [Me2In(PhNCPhNPh)]. It was found to be monomeric and the ligand is attached in a bidentate chelating manner. X-ray crystallographic studies on [RM(PhNCPhNPh)2] (M = Al, Ga, R = Me; M = In, R = Et) and [EtGa(PhNCMeNPh)2] reveal monomeric structures and the presence of chelating amidinato ligands with highly distorted trigonal bipyramidal co-ordination at the metal centre. Cleavage of the metal-alkyl bond in some of these dialkyl- and monoalkyl-metal derivatives on photolysis in the presence of a spin trapping agent was demonstrated using E.S.R. spectroscopy. An X-ray crystallographic study on [In(PhNCPhNPh)3] shows a monomeric structure in which the metal centre is six coordinate and the amidinato ligands are bound in a bidentate chelating manner. Some data have been obtained on the thermal decomposition products of the metal-amidinato complexes in view of their potential use as "III-V" semiconductor precursors. The reactions of the simple N,N'-unsubstituted amidine ligands, butyramidine and trifluoroacetamidine with Me3Ga have been investigated. The former amidine, [NH2CButNH], gave the dimethylgallium-butyramidinato compound and mass spectroscopic data indicate that this compound is oligomeric and exists as both a dimer and monomer in the gas phase. The latter amidine, [NH2CCF3NH], underwent a condensation reaction in the presence of M~Ga to form the complex [Me2Ga{HNC(CF3)NC(CF3)NH}]. The molecular structure of this complex was determined by X-ray crystallography. It was found to consist of a planar six-membered metallocycle containing the N,N'-chelating trifluoroimidoyltrifluoracetamidinato ligand and a distorted tetrahedral co-ordination environment around the metal. Several new indium(III) tetraaza-macrocycle complexes have been prepared using the unsaturated ligand 5,7,12, 14-tetramethyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine ["H2tmtaa"].The molecule structures of the compounds [XIn(tmtaa)] (X = Et, Cp, Cl) have been determined by X-ray crystallography. In each case, the structure consists of an InX fragment bonded to the four nitrogen atoms of the macrocyclic ligand. These structures provide unusual examples of indium in a five co-ordinate square based pyramidal coordination geometry in which the indium is centrally bound above the N4 plane of the macrocycle. The effects of change of both metal size and axial ligand on the molecular geometry of these types of complex have been discussed in detail.
Supervisor: Not available Sponsor: Engineering and Physical Sciences Research Council ; Associated Octel Company
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QD Chemistry Chemistry, Inorganic Chemistry, Organic