Introduction

1. Fortuitous Asides From Low Coordinate Phosphorus ChemistryAmy J. Saunders, Ian R. Crossleyajs51@sussex.ac.ukDepartment of Chemistry, University of Sussex, Brighton, UK

2. Overview – Phosphines – Phosphomides – Cyclophanes – Summary – Acknowledgements Introduction • Molecular wires and NLOs are envisaged to allow electronic communication across conjugated chains • Often comprised of transition metals bridged by alkenes and aromatic rings C. Lapinte, J. Organomet. Chem., 2008, 693, 2898 As an alternative, we propose incorporation of phosphaalkynes into conjugated chains with possible applications in NLO devices and molecular wires • Phosphaalkynes bearing extended conjugation are rare • Those without steric bulk (PhC≡P) are short-lived (t1/2 = 7 minutes) (1) C. Müller, Organomet. Chem., 1996, 512, 141 (2) G. Märkl, Tetrahedron Lett., 1986, 27, 171 (3) C. Jones, J. Organomet. Chem., 2007, 692, 5086

3. Overview – Phosphines – Phosphomides – Cyclophanes – Summary – Acknowledgements Synthetic Methodologies • 1) Synthesis via the Becker Condensation • 2) Synthesis by dehydrohalogenation G. Becker, Z. Naturforsch., B, 1981, 36, 16 H. Grützmacher, Angew. Chem. Int. Ed., 2006, 45, 6159 • Alternative methods for the synthesis of phosphaalkynes exist, but these are the most frequently cited

4. Overview – Phosphines – Phosphomides – Cyclophanes – Summary – Acknowledgements Main Group Chloropropargyls • Few main group chloropropargyls have been reported • Those that have are scattered and often lacking key data and synthetic methods • Products were isolated by recrystallisation and distillation • Characterised fully by NMR spectroscopy and microanalysis V. S. Zavgorodnii, J. Gen. Chem. USSR, 1971, 862 13C{H} NMR spectra of nBu3SnC≡CCH2Cl Saunders, Crossley, manuscript in preparation

5. Overview – Phosphines – Phosphomides – Cyclophanes – Summary – Acknowledgements Synthesis of Propargylic Phosphines • Isolated as analytically pure oils • R’3EC≡CCH2PPh2 selected for further study 1H NMR spectra of nPr3SiC≡CCH2PPh2 31P NMR spectra of nPr3SiC≡CCH2PPh2 Saunders, Crossley, manuscript in preparation

6. Overview – Phosphines – Phosphomides – Cyclophanes – Summary – Acknowledgements Coordination of R3EC≡CCH2PR’2 1H NMR δH 3.74 (t, 2JH-P 3.95 Hz, CH2P). 31P NMR δP 15.9 (s) • Coordination geometry of trans-[Pd{nPr3SiC≡CCH2PPh2}2Cl2] assigned on the basis of virtual coupling of the CH2P protons • Magnetic inequivalence affords virtual triplet signals 1H NMR δH 3.82 (d, 2JH-P 9.55 Hz, CH2P). 31P NMR δP 5.95 (s, 1JP-Pt 3608 Hz). 195Pt NMR δPt −4403 (t, 1JPt-P 3608 Hz) Saunders, Hayes, Crossley, manuscript in preparation

7. Overview – Phosphines – Phosphomides – Cyclophanes – Summary – Acknowledgements Isomerisation Studies • Attempted thermally induced isomerisation unsuccessful 1H NMR spectra of cis-[Pt(nPr3SiC≡CCH2PPh2)2Cl2] 1H NMR spectra of cis- and trans-[Pt(nPr3SiC≡CCH2PPh2)2Cl2] • Isomerisation of driven by irradiation with full spectrum Hg lamp (to 57.5 %)

8. Overview – Phosphines – Phosphomides – Cyclophanes – Summary – Acknowledgements Towards Aromatic Poly(phosphaynes) • Synthesis of PhC≡P was reported by the Becker condensation • The synthesis of di- and tri-phosphaalkynes was attempted • Initial studies afforded a complex mixture of products • Results prompted us to considered that [1,3]-silatropic rearrangement may be causing product degradation C. Müller, Organomet. Chem., 1996, 512, 141

9. Overview – Phosphines – Phosphomides – Cyclophanes – Summary – Acknowledgements Synthesis of Phosphomides • C6H4(1-C(O)PPh2)(4-R) synthesised previously via different methodology • Possible applications in hydroformylation catalysis 31P NMR δP12.9 (t, 3JP-H7.85 Hz). ν(C=O) 1587.6, 1641.5 cm-1 Saunders, Crossley, manuscript in preparation M. L. Clarke, J. Organomet. Chem., 2003, 667, 112

10. Overview – Phosphines – Phosphomides – Cyclophanes – Summary – Acknowledgements Phosphomide Coordination Chemistry 31P NMR δP 36.9 (d, 1JP-Rh 146 Hz). 13C NMR δC201 (d, 1JC-P 17.9 Hz, C(O)P). ν(C=O) 1660 cm-1 • Coordination of C6H4(1-C(O)PPh2)(R) to Rh or Pd induces very little alteration to electron density at carbonyl region (∆ν(C=O) = +20 cm-1) 31P NMR δP 26.1 (br). 13C NMR δC198 (t, 1JC-P 12.4 Hz, C(O)P). ν(C=O) 1660 cm-1

11. Overview – Phosphines – Phosphomides – Cyclophanes – Summary – Acknowledgements Phosphaalkenes? 1H NMR δH 1.55 (d, 2JH-P 3.10 Hz, CH3). 31P NMR δP 32.7 (s) • Synthesis of C6H4(1-C(OSiMe3)=PMe)(3-COCl) attempted • Diphosphametacyclophane {3-CO-C6H4-C(O)PMe}2 afforded instead • Suggests formation of acyl phosphine, but no [1,3]-silatropic rearrangement • Crystal structure shows adoption of a butterfly conformation with both Me groups mutually exo P…P = 5.11 Å P-CH3 = 1.892 Å C – O = 1.211 Å • Saunders, Crossley et al, Chem. Commun., 2012, 48, 5766

12. Overview – Phosphines – Phosphomides – Cyclophanes – Summary – Acknowledgements Coordination of {3-CO-C6H4-C(O)PMe}2 1H NMR δH 2.02 (d, 2JH-P 7.19 Hz, CH3). 31P NMR δP 15.9 (d, 2JP-P 441 Hz, 1JP-Pt 1929Hz, PEt3), 51.3 (d, 2JP-P 441 Hz, 1JP-Pt 2812 Hz, PCH3) Pt – P = 2.294 Å P – CH3 = 1.214 Å Pt .. P = 4.558 Å C – O = 1.208 Å 1H NMR δH 1.70 (d, 2JH-P 3.19 Hz, CH3), 2.33 (t, 2JH-P 3.14 Hz, CH3). 31P NMR δP 28.4 (s), 33.2 (JP-Pt 2296 Hz) • Saunders, Crossley et al, Chem. Commun., 2012, 48, 5766

13. Overview – Phosphines – Phosphomides – Cyclophanes – Summary – Acknowledgements On-going Metacyclophane Studies • Further evidence of successful acyl phosphine formation 1H NMR δH 1.39 (d, 2JH-P 3.41 Hz, CH3). 31P NMR δP 20.2 (s) 1H NMR δH1.63 (m, 6H, 2JH-P 6.61 Hz CH3). 31P NMR δP30.2 (d, 2JP-H= 5.70 Hz) • Preferential reaction at one moiety • Allows future forays into synthesis of asymmetric phosphametacyclophanes • Different donor atoms… • {3-CO-C5H3N-C(O)PMe}2 isolated as an orange solid • Successful incorporation of pyridine rings into diphosphametacyclophane

14. Overview – Phosphines – Phosphomides – Cyclophanes – Summary – Acknowledgements Summary • Further research continues towards • Application of phosphomides in hydroformylation catalysis • Development of phosphaalkenes and phosphaalkynes • Synthesis of phosphametacyclophanes based on {3-CO-C6H4-C(O)PMe}2

15. Overview – Phosphines – Phosphomides – Cyclophanes – Summary – Acknowledgements Acknowledgements • Leverhulme Trust • The Royal Society • Isomerisation study - Jack Hayes • NMR - Dr Iain Day • X-ray - Dr Martyn Coles, Dr Mark Roe • Dr Ian Crossleyand the Crossley research group • The EWPC-10 organisers • Thank you for listening!