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Durham e-Theses
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Synthesis of multidentate PNE ligands and their late transition metal coordination chemistry

Anderson, Carly Elizabeth (2007) Synthesis of multidentate PNE ligands and their late transition metal coordination chemistry. Doctoral thesis, Durham University.

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Abstract

This thesis describes the synthesis of a family of potentially tridentate PNE (E = NMe, О, S, СН(_2), NPh) ligands comprising a six-membered diheteroatomic saturated ring system bearing a pendent phosphine donor arm and studies on their coordination chemistry with a selection of late transition metals. Chapter 1 comprises an overview of the nature of the bonding of phosphine, amine, ether and thioether donors to metals and reviews the dynamic behaviour of saturated heteroatom-containing ring systems in solution. Selected examples of the coordination chemistry and catalytic applications of complexes of Pd, Pt and Rh are given. Chapter 2 details the concise synthesis of variously-substituted diphenylphosphine- bearing PNE ligands, Ph(_2)PCH(_2)CH(_2)N(CH(_2)CH(_2)) (_2)E (E = NMe, 2.4-1; E = о, 2.4-2; E = S, 2.4-3; E = СН(_2), 2.4-4; E = NPh, 2.4-5; E = NCH(_2)CH(_2)PPh(_2), 2.4-7), by reaction of diphenylvinylphosphine with a cyclic secondary amine. The synthesis of both hydrochloride and chalcogen derivatives are also reported. Attempts to synthesise a related family of PNE ligands with amino-substituents at P were unsuccessful. Similar reactions of allyldiphenylphosphine with N-methylpiperazine led to the formation of Ph(_2)PCH(_2)CH(Me)N(CH(_2)CH(_2)) (_2)NMe as a result of base-catalysed isomerisation of the allyl phosphine. The complexation of the PNE ligands with a variety of Pd(II) fragments is detailed in Chapter 3. Reaction with [PdCl(_2) (MeCN) (_2)] affords the [PdCl{k(^3)-PNE}](^+) Сl(^-) salts when E = NMe, O, S and CH(_2), although when E = NPh and NCHzCHjPPha, the expected products were not obtained. A bidentate [PdCİ2{K^-PN(NMe)}] isomer of 3.1-1 was characterised crystallographically although this was indicated not to be representative of the bulk sample, which consisted mainly of the tridentate [PdCl{Kľ^-PNE}] (^+0Cl(^-)isomer. Treatment of 3.1-l with MgSO(_4) affords the unusual [PdCl{k(^3)-PNE}](^+)1/2[Mg(SO(_4))շ.41-1շՕ] complex which was characterised crystallographically. Reaction of 2.4-1 ֊ 2.4-4 with [PdCl(Me)(cod)] and [PdMe(_2)(tmeda)] affords the [PdCl(Me){K(^2)- PN(E)}] and [PdMe(^2){K(^2)-PN(E)}](^+)Cl(_1) complexes, respectively. Chapter 4 describes the coordination chemistry of the PNE ligands with Pt(II) metal fragments. The reaction of 2.4-1 - 2.4-3 with [PtCİ2(cod)] affords the doubly ligated [PtCl{K^-PN(E)} {k'-P(NE)}]^ СГ complexes with both stoichiometric and half molar equivalents of the platinum precursor. Reaction of the PNE ligands with [р\рŽ+і{ц-С1}(РЕїз)]2 gives [PtCl(PEt3){K^-PN(E)}] complexes in all cases.The coordination of the PNE ligands with Rh(I) metal centres is detailed in Chapter 5. Reaction of 2.4-1 ― 2.4-4 with [Кіі2{ц-С1}2(00)4] affords the [RhCl(CO){PNE}] complexes in all cases, although when E = NMe and ร, dynamic interconversion between [RhCl(CO){K^-PN(E)}] and [Rh(CO){K^-PNE}]^ Сl(^-) complexes is observed by low temperature NMR spectroscopy. By contrast, no isomerisation is noted when E = О. When E = NPh and NCH2CH2PPh2, the expected products were not obtained. Abstraction of the metal-bound chloride from [RhCl(CO){PNE}] proved successful when E-= NMe and S but this reaction failed to afford the expected product when E = 0, even in MeCN solution. Full experimental data and methods of preparation for the compounds in this thesis are listed in Chapter 6 with supplementary crystallographic data available in the Appendices.

Item Type:Thesis (Doctoral)
Award:Doctor of Philosophy
Thesis Date:2007
Copyright:Copyright of this thesis is held by the author
Deposited On:09 Sep 2011 09:49

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