Versatile Phosphorus Ligands : Synthesis, Coordination Chemistry and Catalysis
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Versatile phosphorus ligands : synthesis, coordination chemistry and catalysis Citation for published version (APA): Vlugt, van der, J. I. (2003). Versatile phosphorus ligands : synthesis, coordination chemistry and catalysis. Technische Universiteit Eindhoven. https://doi.org/10.6100/IR570885 DOI: 10.6100/IR570885 Document status and date: Published: 01/01/2003 Document Version: Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. 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If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, please follow below link for the End User Agreement: www.tue.nl/taverne Take down policy If you believe that this document breaches copyright please contact us at: [email protected] providing details and we will investigate your claim. Download date: 30. Sep. 2021 Versatile Phosphorus Ligands Synthesis, Coordination Chemistry and Catalysis Versatile Phosphorus Ligands Synthesis, Coordination Chemistry and Catalysis PROEFSCHRIFT ter verkrijging van de graad van doctor aan de Technische Universiteit Eindhoven, op gezag van de Rector Magnificus, prof.dr. R.A. van Santen, voor een commissie aangewezen door het College voor Promoties in het openbaar te verdedigen op maandag 27 oktober 2003 om 16.00 uur door Jarl Ivar van der Vlugt geboren te Schiedam Dit proefschrift is goedgekeurd door de promotoren: prof.dr. D. Vogt en prof.dr. D.J. Cole-Hamilton CIP-DATA LIBRARY TECHNISCHE UNIVERSITEIT EINDHOVEN Vlugt, Jarl Ivar van der Versatile phosphorus ligands : synthesis, coordination chemistry and catalysis / by Jarl Ivar van der Vlugt. – Eindhoven : Technische Universiteit Eindhoven, 2003. Proefschrift. – ISBN 90-386-2675-4 NUR 913 Subject headings: rhodium catalyzed hydroformylation / phosphorus ligands / coordination chemistry / silsesquioxanes / transition metal complexes Omslag: Origineel ontwerp van wijlen Paul Snoek en Rikkes Voss. Huidige vormgeving door Jarl Ivar van der Vlugt en Jan Willem Luiten. Een verantwoorde uitleg voor dit ontwerp kan worden gevonden door creativiteit en dichterlijke vrijheid te koppelen aan een nadere bestudering van de inhoud van dit proefschrift. Druk: Universiteitsdrukkerij, Technische Universiteit Eindhoven. Copyright 2003 by Jarl Ivar van der Vlugt. The research described in this thesis was financially supported by the National Research School Combination – Catalysis (NRSC-Catalysis). ‘Uiteindelijk is het niets anders dan: leuk gezegd, mooi gedaan, goed gevonden.’ Youp van ‘t Hek ‘Life is just chemicals. A drop here, a drip there. Everything’s changed.’ Terry Pratchett ‘Ik zweer bij de schoonheid van het nutteloze en zie het nutteloze van de schoonheid in.’ Paul Snoek ‘De zon is mijn oudste vriend en hij weet het. De zon is immers een vader. Mijn moeder is de moeder van een alchemist, met gouden schouders. Mijn ouders zijn mijn beste werk, ik heb ze lief, ik draag ze op en in mijn handen, breekbaar als een koppel witte duiven.’ (vrij naar) Paul Snoek Summary Phosphorus containing compounds are among the most widely used ligands in homogeneous catalysis employing transition metal complexes. Undoubtedly this is due to the enormous variety that can be achieved in the design of such compounds. Amidst all reactions performed by means of homogenous catalysis, the hydroformylation, i.e. the conversion of a C-C double bond to an aldehyde moiety by reaction with synthesis gas, is often considered a true success story, both with respect to the application of homogeneous catalysis in an industrial process as well as for underlining the importance of ligand design as a key factor of control over the outcome of the catalytic reaction. The classification used to distinguish phosphorus ligands as far as the oxidation state of the phosphorus atom is concerned, i.e. phosphines, phosphinites, phosphonites and phosphites, is appropriate for a rough subdivision, although recent developments include the incorporation of non carbon or oxygen substituted compounds, viz. by employing nitrogen or silicon. A thorough understanding of the factors governing a) the properties of the ligands synthesized and b) the outcome of catalytic reactions in which such compounds are applied is essential for clever design and synthesis of next generations of phosphorus containing ligands. This understanding can be achieved by i) characterization of the bare ligand system, ii) unraveling the coordination of such species towards desired transition metals, and iii) studying the catalytic system incorporating such ligands. Various tools are available, ranging from chemical reactivity tests, molecular modelling, X- ray crystallography to in situ spectroscopic techniques, such as NMR and IR. The work described in this dissertation is aimed at the development (i.e. design and synthesis) of novel classes of phosphorus ligands, thereby i) providing a modular synthetic approach by employing backbone scaffolds that have so far remained untouched but which are intrinsically promising, for instance from an economic point of view, ii) triggering academic curiosity by combination of two areas of expertise that may lead to exciting transition metal chemistry, and/or iii) giving insight into the potential of compounds with specific phosphorus moieties in homogeneous catalysis, and to apply these new compounds in the rhodium catalyzed hydroformylation. To date, many different types of ligands have been employed in this sort of reactions, allowing for good comparison and thus (fair) judgement of the newly applied systems and their respective added values. In Chapter one, the literature dealing with the design of ligands, applied in the hydroformylation of alkenes and related reactions, is reviewed. The four main classes of phosphorus ligands, are considered. Besides this topic special attention is given to the coordination chemistry Summary reported for both phosphinites and phosphonites. The main conclusions that can be derived from this survey are i) that phosphines are still and by far the most studied of all phosphorus ligands, with the focus nowadays on the development of chiral ligands for asymmetric catalysis, ii) that new phosphites and their transition metal complexes continue to create opportunities for application in the Rh catalyzed hydroformylation, although the synthetic limitation –the ligand backbone needs to have an hydroxyl-functionality - can not be disregarded, iii) that there is renewed interest in the chemistry of phosphinites and iv) that the coordination chemistry of especially phosphonites (and to a lesser extent phosphinites as well) with transition metals in general is hardly explored to date. Chapter two is dedicated to the ‘neglected’ class of phosphonite ligands and sterically constrained diphosphonites are considered as specific representatives thereof. The coordination chemistry of some typical examples from this new class of ligands is described, resulting in the characterization of seven molecular structures of Pd, Pt and Rh complexes with diphosphonites. Subtle structural differences in the ligands are shown to have great impact on the coordination mode of the ligand to the various metals. Rh catalysts comprised of these diphosphonite ligands are tested in the hydroformylation of 1-octene and 2-butene. For both substrates high activities and selectivities are obtained, showing for the first time the successful application of diphosphonite ligands in such reactions. In case of 2-butene, selective conversion to n-pentanal is possible in up to 66% under the chosen reaction conditions. NMR and IR spectroscopic techniques are used to gain insight in the catalytic resting state of the rhodium complexes present under catalytic conditions. Predominant formation of complexes with the diphosphonite ligand coordinated in an equatorial-equatorial fashion is observed. Based on the results obtained with achiral diphosphonites in the rhodium catalyzed hydroformylation in the previous chapter, Chapter three describes the use of a chiral diphosphonite with a xanthene backbone and binaphthyl units on the P atoms. The coordination of this ligand with Pd, Pt and Rh is examined, which results in the characterization of the molecular structures for both the cis-Pd and the cis-Pt complex. In both