Synthesis of discrete models for aluminophosphate-type molecular sieves
Synthesis of discrete models for aluminophosphate-type molecular sieves
This thesis reports on the reactions of alkylaluminium and gallium reagents with a number of different phosphorus acids, including substituted phosphates, phosphinic acids and phosphonic acids which afford dimeric metal phosphates [R2M(O)2P(OR')2]2 (M = Al, Ga; R = Me, Et, Pr, iBu, Oc, OEt, Cl; R' - Et, Ph), dimeric metal phosphinates [R2M(O)2PR'2]2 (M = Al, Ga; R = Me, Et, Pr, iBu, Oc, OEt, Cl; R' = Me, Ph, H) and tetrameric metal phosphonates [RM(O)3PR']4 (M = Al, Ga; R = Me, Et, iBu, Cl; R' = Me, Et, Ph) respectively. All of these structures contain Al-O-P and Ga-O-P linkages as are found in the aluminophosphate and gallophosphate molecular sieves. The reactions of the alkylaluminium and alkylgallium reagents were found to give analogous products with the same degree of association. X-ray structures are reported for [Me2Al(O)2PPh2]2 and [Et2Ga(O)2PPh2]2 and show both products to be dimers containing puckered eight membered (M-O-P-O)2 rings, which adopt chair conformations. EXAFS spectra were recorded for a number of the gallium compounds for which crystal structure could not be obtained. The EXAFS derived distances around the gallium centre in [Et2Ga(O)2PPh2]2 were found to be in good agreement with its crystal structure.
The metal phosphonates, [RM(O)3PR']4, synthesised are the first examples of aluminium and gallium phosphonates reported. These were shown to be tetrameric by molecular weight measurements. A cube structure has been proposed for these compounds in which each face of the cube consists of an eight membered (M-O-P-O)2 ring. Each metal or phosphorus atom forms a corner of the cube.
The reactions of trialkylgallium reagents with the bulky phenols, 2,6-di-tert-buty-4-methylphenol and 2,6-diphenylphenol are described. The X-ray structure of (2,6-diphenyphenoxy)diethylgallium, [Et2Ga(DPP)]2 showed this compound to be dimeric with a core consisting of a four membered (Ga-O-Ga-O) ring.
University of Southampton
Browning, Darren Jonathan
1997
Browning, Darren Jonathan
Browning, Darren Jonathan
(1997)
Synthesis of discrete models for aluminophosphate-type molecular sieves.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
This thesis reports on the reactions of alkylaluminium and gallium reagents with a number of different phosphorus acids, including substituted phosphates, phosphinic acids and phosphonic acids which afford dimeric metal phosphates [R2M(O)2P(OR')2]2 (M = Al, Ga; R = Me, Et, Pr, iBu, Oc, OEt, Cl; R' - Et, Ph), dimeric metal phosphinates [R2M(O)2PR'2]2 (M = Al, Ga; R = Me, Et, Pr, iBu, Oc, OEt, Cl; R' = Me, Ph, H) and tetrameric metal phosphonates [RM(O)3PR']4 (M = Al, Ga; R = Me, Et, iBu, Cl; R' = Me, Et, Ph) respectively. All of these structures contain Al-O-P and Ga-O-P linkages as are found in the aluminophosphate and gallophosphate molecular sieves. The reactions of the alkylaluminium and alkylgallium reagents were found to give analogous products with the same degree of association. X-ray structures are reported for [Me2Al(O)2PPh2]2 and [Et2Ga(O)2PPh2]2 and show both products to be dimers containing puckered eight membered (M-O-P-O)2 rings, which adopt chair conformations. EXAFS spectra were recorded for a number of the gallium compounds for which crystal structure could not be obtained. The EXAFS derived distances around the gallium centre in [Et2Ga(O)2PPh2]2 were found to be in good agreement with its crystal structure.
The metal phosphonates, [RM(O)3PR']4, synthesised are the first examples of aluminium and gallium phosphonates reported. These were shown to be tetrameric by molecular weight measurements. A cube structure has been proposed for these compounds in which each face of the cube consists of an eight membered (M-O-P-O)2 ring. Each metal or phosphorus atom forms a corner of the cube.
The reactions of trialkylgallium reagents with the bulky phenols, 2,6-di-tert-buty-4-methylphenol and 2,6-diphenylphenol are described. The X-ray structure of (2,6-diphenyphenoxy)diethylgallium, [Et2Ga(DPP)]2 showed this compound to be dimeric with a core consisting of a four membered (Ga-O-Ga-O) ring.
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Published date: 1997
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Local EPrints ID: 463107
URI: http://eprints.soton.ac.uk/id/eprint/463107
PURE UUID: 720cfc3a-b6b2-49d8-964b-3aff035f9733
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Date deposited: 04 Jul 2022 20:44
Last modified: 04 Jul 2022 20:44
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Author:
Darren Jonathan Browning
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