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Robert Turbervill University of Oxford

Reactivity of Heptaphosphide Zintl Anions Towards Unsaturated Bonds. Robert Turbervill University of Oxford. 10 th European Workshop on Phosphorus Chemistry 2012 (Regensburg, Germany) March 18 th -20 th 2013.

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Robert Turbervill University of Oxford

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  1. Reactivity of Heptaphosphide Zintl Anions Towards Unsaturated Bonds Robert Turbervill University of Oxford 10th European Workshop on Phosphorus Chemistry 2012 (Regensburg, Germany) March 18th-20th 2013

  2. Zintl phases: Ionic, salt-like intermetallics formed between group 1 (alkali) or group 2 (alkaline- earth) elements and post transition metals or metalloids from groups 13, 14, 15 or 16.

  3. Manriquez, V.; Honle, W.; von Schnering, H. G. Z. Anorg. Allg. Chem. 1986, 539, 95. Zintl phases: Ionic, salt-like intermetallics formed between group 1 (alkali) or group 2 (alkaline- earth) elements and post transition metals or metalloids from groups 13, 14, 15 or 16.

  4. Synthesis Stoichiometric mixtures of elements loaded in an inert atmosphere glovebox Nb tube Arc welder used to seal niobium tubes Nb tubes sealed in silica ampoules under vacuum Tube furnace at high temperature (600°C) for 3 days Nb tube

  5. Structure and solution chemistry pyridine Three phosphorus environments (basal, waist, apical) Each two-coordinate phosphorus carries a formal negative charge Highly fluxional in solution and solid state K3P7(s) + H2O + 18-crown-6 [K(18-crown-6)]2[HP7] Contains 5-10% unidentified impurity phase as synthesized 85% yield, multigram scale, analytically pure Sen, T.; Poupko, R.; Fleischer, U.; Zimmermann, H.; Luz, Z. J. Am. Chem. Soc.2000, 122, 889 However, in practice, most reactivity can be done with the Zintl phase

  6. Chemistry so far… [P7{FeCp(CO)2}3]Fenske, 1996 [P7Tl]2–Goicoechea, 2010 [Fe(HP7)2]2–Goicoechea, 2011 η1- η2- η4- 2 electron donor to metal centre 4 electron donor to metal centre 6 electron donor to metal centre Many examples of metallated cages, very little “phospha-organic” chemistry…

  7. Reactions of [HP7]2- with CO2 analogues DMF, 20 °C [HP7]2– + RN=C=E [P7C(E)(HNR)]2– amide functionalized cage amidine functionalized cage Works for RN=C=O (R = Ad, Dipp), RN=C=NR (R = Dipp, iPr, Cy) NH observed at 5.88 ppm NH observed at 6.29 ppm Turbervill, R. S. P.; Goicoechea, J. M. Chem. Commun.2012, 48, 1470-1472 and unpublished work

  8. –50 ºC 31P NMR [P7(NHDipp)(NDipp)]2- RT 31P NMR spectrum shows that the cluster anions are fluxional in solution

  9. Reactions of [HP7]2- with carbodiimides 31P NMR spectrum shows 5 resonances:+12.5, –29.0, –64.2, –113.8, –129.5 ppm Protonation only possible for [P7C(NDipp)(NHDipp)]2–(R = Dipp, iPr, Cy) Turbervill, R. S. P.; Goicoechea, J. M. Organometallics, 2012, 31, 2452-2462

  10. Reactions of [P7]3-with alkynes NMR spectra consistent w/ AA’BXX’ system 1JP–P = –493 Hz; 2JP–P = 10 Hz; 2JH–P = 48 Hz; 3JH–P = 18 Hz; 3JH–H = 8 Hz Turbervill, R. S. P.; Goicoechea, J. M. Chem. Commun., 2012, 48, 6100-6102

  11. Preliminary coordination chemistry [P3C2H2]– + [Ru(COD){CH3C(CH2)2}2] THF, 45 °C [Ru(P3C2H2){CH3C(CH2)2}2]– + COD

  12. Preliminary coordination chemistry Arsenic analogue structurally characterised as [K(2,2,2-crypt)]+ salt

  13. Accessible 1,2,3-tripnictolides Several anions are accessible via direct reaction of an alkyne with K3E7 (E = P, As) All structurally authenticated as either P or As; [K(2,2,2-crypt)]+ or [K(18-crown-6)]+ salts

  14. 1,2,3-Triphospholide complex formation 31P NMR spectrum shows upfield shifts of approximately 200-250 ppm on complexation Analysis of complexes by IR spectroscopy reveals that the ligands have increased π-acceptor properties relative to Cp− (c.f. 1,2,4-triphospholides; Nixon/Green) IR νCO (cm−1): [(P3C2H2)Mo(CO)3]−: 1916, 1834, 1814 [(C5H5)Mo(CO)3]−: 1884, 1760 Turbervill, R. S. P.; Jupp, A; McCullough, P. S. B.; Ergöçmen, D.; Goicoechea J. M., accepted

  15. Coordination chemistry of [P3C2(2-py)H]– CD2Cl2, 20 °C [P3C2(2-py)H]– + Mo(COD)(CO)4 [κ2-(P3C2H{2-py})Mo(CO)4]– κ2-complex loses CO in solution to form the η5-complex Turbervill, R. S. P.; Goicoechea J. M., submitted

  16. Bimetallic systems Turbervill, R. S. P.; Goicoechea J. M., submitted

  17. Conclusions and future work • [P7]3– cages possess a rich chemistry with organic compounds • Useful reagent to access elusive “phospha-organic” molecules • Currently exploring salt methathesis and redox chemistry of 1,2,3-tripnictolides • Promising results with other organic substrates

  18. Acknowledgements Other DPhil student: Caroline Knapp (presenting a poster here) Part II students: Andrew Jupp, Phil McCullough (2011-12), Bethan Westcott (2012-13) Summer student (ERASMUS): Doruk Ergöçmen (2012) NMR: Dr. Nick Rees Supervisor: Dr. Jose Goicoechea Funding: Andy Ben Jack Caroline Jose Jordan Bethan Gaby

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