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Reactivity of bridging Pentelidene Complexes

This article explores the reactivity of bridging pentelidene complexes, particularly focusing on phosphinidene complexes and their interaction with diphosphenes and primary phosphines. It highlights the general reactivity patterns, including mechanisms like nucleophilic attack and thermolysis scenarios. Detailed studies employing techniques such as NMR and DFT methods reveal critical insights into the bonding characteristics and electron interactions of these complexes. The paper encapsulates the essential contributions to the understanding of phosphinidene chemistry and discusses the stability and reactivity of various phosphinidene environments.

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Reactivity of bridging Pentelidene Complexes

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  1. ReactivityofbridgingPentelideneComplexes

  2. Contents: • Overview on phosphinidene complexes • General reactivity pattern • Reactivity towards diphosphenes • Reactivity towards primary phosphines

  3. Phosphinidenecomplexes: 1 µ2 µ3 µ4 M. Ruiz, A. J. Carty G. Huttner et al, Acc. Chem. Res. 1986, 19, 406-413 M. F. Lappert 1979 A. H. Cowley 1990 stablecompoundswithbulkysubstituents R orbulkyligands Cowley, Lappert, Wolczanski, Schrock, Hey-Hawkins intermediates withlessbulkysubstituents R Mathey, Lammertsma, Streubel

  4. Preparation: 31P: δ= 1076 ppm (s,1JWP = 166 Hz,187 Hz) Jutziet al., J. Organomet. Chem.1990, 390, 317-322.

  5. sp2-hybridisation at the phosphorus atom • phosphinidene as m2-4e--ligand • p-back bonding from the metal to the P atom a3-centre-4p-electron system Bondsituation: LUMO -4.28eV HOMO -5.45eV

  6. Reactivitypattern: Cp* migration Cp* shift Cp* ring expansion Cp* elimination nucleophilicattack

  7. Thermolysis: Scheer et al., Chem. Eur. J.1998, 4, 1917-1923.

  8. Photolysis: Scheer et al., Eur. J. Inorg. Chem.2001, 1661-1663.

  9. Photolysiswithdiphosphenes: P1 P1 P1 P1` P2 As1 d(P1-As1) = 2.216(1) Å d(P1-P2) = 2.1122(10) Å M. Scheer, C. Kuntz, M. Stubenhofer, M. Linseis, R.Winter, M. Sierka,Angew. Chem. Int. Ed. 2009, 48, 2600 –2604.

  10. Photolysiswithdiphosphenes: P2 As1 P3 P1 P1 P2 H1 H1 d(P1-P2) = 2.187(3) Å d(P2-P3) = 2.075(3)Å d(P1-As1) = 2.179(2) Å d(P2-As1) = 2.298(2)Å radical: d(P1-P2) = 2.1122(10) Å radical: d(P1-As1) = 2.216(1) Å

  11. Cyclovoltammogram: E½ (Ox.) = 0.17 V E½ (Ox.) = 0.17 V E½ (Red.) = –0.81 V E½ (Red.) = –0.81 V rate ofspeed: 100 mV/s

  12. Oxidation andreduction: P3 P1 P1 P2 P2 As1 bondlength: d(P1-P2) = 2.070 (3) Å d(P2-P3) = 2.065 (3) Å bondlength: d(P1-As1) = 2.186(3) Å d(P2-As1) = 2.191(2) Å

  13. Oxidation andreduction: P2 P3 P1 bondlength: d(P1-P2) = 2.256 (7) Å d(P2-P3) = 2.085 (6) Å

  14. Summary: M. Stubenhofer, C. Kuntz, M. Bodensteiner, U. Zenneck, M. Sierka, M. Scheer Chem. Eur. J.2010, 13, 1745-1747 .

  15. Reactivitytowardsprimaryphosphines: N1 N1 P2 B1 P1 R = H2P-BH2NMe3 B1 P1 As1 d(P1-P2) = 2.237(2) Å d(As1-P1) = 2.352(3) Å M. Scheer, C. Kuntz, M. Stubenhofer, M. Zabel, A. Y. Timoshkin, Angew. Chem. Int. Ed. 2010, 49, 188 –192.

  16. Reactivitytowardsprimaryphosphines: R = Ph P1 P2 d(P1-P2) = 2.197(1) Å M. Scheer, C. Kuntz, M. Stubenhofer, M. Zabel, A. Y. Timoshkin, Angew. Chem. Int. Ed. 2010, 49, 188 –192.

  17. Reactivitytowardsprimaryphosphines: R = Ph M. Scheer, C. Kuntz, M. Stubenhofer, M. Zabel, A. Y. Timoshkin, Angew. Chem. Int. Ed. 2010, 49, 188 –192.

  18. Reactivitytowardsprimaryphosphines: P1 H1 P2 d(P1-P2) = 2.239(2) Å DFT-methods (B3LYP/6-31G* (ECP for W)) M. Scheer, C. Kuntz, M. Stubenhofer, M. Zabel, A. Y. Timoshkin, Angew. Chem. Int. Ed. 2010, 49, 188 –192.

  19. Reactivity towards primaryphosphines: R =tBu M. Scheer, C. Kuntz, M. Stubenhofer, M. Zabel, A. Y. Timoshkin, Angew. Chem. Int. Ed. 2010, 49, 188 –192.

  20. Reactivitytowardsprimaryphosphines: As1 P3 P2 P1 P1 P2 d(P1-As1) = 2.334(3) Å d(As1-P2) = 2.369(3) Å 31P{1H}-NMR: symd = -17.2 ppm asymd = -20.8 ppm (d, 2JP,P = 3Hz) d = -18.7 ppm (d, 2JP,P = 3Hz) d(P1-P2) = 2.215 (2) Å d(P2-P3) = 2.238(2) Å 31P{1H}-NMR: d= -90.7 ppm (dd, 1JP,P = 197 Hz d = -13.4 ppm (d, 1JP,P = 197 Hz)

  21. Reactivitytowardsprimaryphosphines:

  22. M. Stubenhofer, C. Kuntz, G.Balázs, M. Zabel, M. Scheer, Chem. Commun. 2009, 13, 1745 – 1747.

  23. Acknowledgement: • Prof. Manfred Scheer • Scheer Group • DFG

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