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Studies into the synthesis of primary phosphines for the preparation of macrocycles by template methods.

Reixach, Elisenda. 2006. Studies into the synthesis of primary phosphines for the preparation of macrocycles by template methods. PhD Thesis, Cardiff University.

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Abstract

This thesis is focused in the synthesis of phosphine-based macrocycles by template methods. Furthermore, it explores some alternative methods for the synthesis of known and unknown polydentate primary phosphine compounds necessary for the preparation of new macrocycles. Following this new procedure the novel tripodal primary phosphine cis, cis-1,3,5-triphosphinomethylcyclohexane (2.15) has been prepared in good yields as well as the reported bis(2-phosphinoethyl)amine (PNP, 3.4). Mono-alkylation of 3.4 allowed the preparation of the asymmetric 2-(allylphosphino)-N-(2-phosphinoethyl)ethanamine ligand (3.16) in low yields. Whilst ligands 2.15 and 3.16 failed to form well-defined facially coordinated molybdenum(0) and chromium(0) complexes respectively, 3.4 formed octahedral complexes with Cr(0) and Fe(II) metals, [{fac-Cr(CO)3(PNP)}, 3.8] and [[{n5-C5H4(SiMe3)}Fe(PNP)]PF6, 3.10]. Different attempts have been made to cyclise the facially coordinated chromium complex 3.8, however all of them have failed. The synthesis of 3.8 and 3.10 has been confirmed by X-ray diffraction. The synthesis of a new Mn(I) 9-membered tribenzanulated triphosphamacrocycle complex [Mn(CO)3{(C6H4F)PC6H4PHC6H4PHC6H4}]OTf, 4.10 has been successfully synthesised by sequential introduction of 1,2-diphosphinobenzene and tris(2-fluorophenyl)phosphine on a manganese(I) complex and subsequent addition of t-BuOK. Alkylation of the two secondary phosphorus of 4.10 with Mel allowed the isolation of the more stable manganese complex [Mn(CO)3{(C6H4F)PC6H4P(CH3)6H4P(CH3)C6H4}]OTf/I 4.12. The liberation of the phosphine trioxide macrocycle, {(C6H4F)P(0)C6H4P(0)(CH3)C6H4(0)(CH3)C6H4} 4.14 from the metal has been achieved using 4-methylmorpholine N-oxide in excess. In addition, the X-ray crystal structures of the non-cyclised precursor intermediate [Mn(CO)3{(C6H4F)3P}{C6H4(PH2)2-o}] OTf 4.9 and the half cyclised intermediate [Mn(CO)3{(C6H4F)2PC 6H4PHC6H4PH2}] OTf 4.11 as well as the final macrocycle 4.12 have also been established.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Chemistry
Subjects: Q Science > QD Chemistry
ISBN: 9781303174131
Date of First Compliant Deposit: 30 March 2016
Last Modified: 12 Feb 2016 23:11
URI: http://orca-mwe.cf.ac.uk/id/eprint/54270

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