Straightforward Access to Stable, 16-Valence-Electron Phosphine-Stabilized Fe Olefin Complexes and Their Reactivity

• Published in: Organometallics Vol. 36; no. 3; pp. 605 - 613
• Main Authors: Burcher, Benjamin, Sanders, Kevin J, Benda, Ladislav, Pintacuda, Guido, Jeanneau, Erwann, Danopoulos, Andreas A., Braunstein, Pierre, Olivier-Bourbigou, Hélène, Breuil, Pierre-Alain
• Format: Journal Article
• Language: English
• Published: American Chemical Society 13.02.2017
• Subjects: Chemical Sciences; Coordination chemistry; SOLID-STATE NMR; ELECTRON-PARAMAGNETIC-RESONANCE; LOW-COORDINATE IRON; PI-COMPLEXES; DINITROGEN COMPLEXES; EPR PARAMETERS; ADIABATIC PULSES; MULTIVINYLSILICON LIGANDS; TRANSITION-METALS; UNACTIVATED ALKENES
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/acs.organomet.6b00803

The use of the dialkene divinyltetramethyldisiloxane (dvtms) allows easy access to the reactive 16-valence-electron complexes [Fe-0 (L-L(dvtms)] (L-L = dppe (1,2-bis-(diphenylphosphino)ethane; 1), dppp (1,2-bis(diphenylphOsphino)-propane; 2), pyNMe:P('Pr)(2) (N-(diisopropylphosphino)-N-methylpyridin-2-amine; 4), dipe (1,2-bis(diisopropylphosphino)ethane; 5)) and [Fe-0(L)(2)(dvtms)] (L = PMe3; 3) by a mild reductive route using AlEt2(OEt) as reducing agent. In contrast, by the "same methodology, the 18-valence-electron complexes [Fe-0(L-L)2(ethylene)] (L-L = dppin (1,2-bis(diphenylphosphino)methane; 6),.dppa (1,2-bis-(diphenylphosphino)amine; 7), dppe (8)) were obtained, Which do not contain dvtms. In addition, a combined DFT and solid-state paramagnetic NMR methodology is introduced for the structure determination of 5. A comparative study of the reactivity of 1, 2, 4-6, and 8 with 3-hexyne highlights emerging mechanistic implications for C C coupling reactions using these complexes as catalysts.