Events & Seminars > Event Details

Where:

4:00pm
Room 304, Chemistry Building

From C-C agostic interactions to C-H bond activation

Speaker:

Professor Michel Etienne
University of Toulouse

Hosted by: Professor Brent Gunnoe

Despite their relative scarcity, agostic complexes where a CC,[1] rather than a CH, bond interacts with a main group or transition metal have been attracting strong attention recently. This stems from their involvement in metallacyclobutanes that are intermediates in alkene metathesis reactions,[2] and also in their ability to model CC s-complexes and CC bond cleavage.[3]

I will summarize some of our results highlighting structural (solid state and solution) and reactivity data as well as the importance of computational modelling. Two types of a-CC agostic complexes based on the cyclopropyl ligand will be considered: (i) hydrotris(pyrazolyl)borate niobium complexes [TpMe2NbX(c-C3H5)(MeCCMe)] (X = Cl, Me, etc.) from which hydrocarbon CH bond activation has been developed,[4] and (ii) an heterobimetallic lithium yttrium complex [(h5-C5Me5)2Y(m-c-C3H5)2Li(thf)] that exhibits two types of CC agostic interactions, one with Li with an electrostatic character, one with Y with a more covalent character.[5] Time permitting, I will present results on catalytic methane functionalization based on highly fluorinated scorpionate-based silver complexes that have emerged from these studies.[6]

 

 [1] A review and selected examples: (a) M. Etienne, A. S. Weller, Chem. Soc. Rev. in press (b) S. K. Brayshaw, E. L. Sceats, J. C. Green, A. S. Weller, Proc. Natl. Acad. Sci. U.S.A. 2007, 104, 6921; (c) S. Scheins, M. Messerschmidt, M. Gembicky, M. Pitak, A. Volkov, P. Coppens, B. G. Harvey, G. C. Turpin, A. M. Arif, R. D. Ernst, J. Am. Chem. Soc. 2009, 131, 6154; (d) M. Gandelman, L. Konstantinovski, H. Rozenberg, D. Milstein, Chem. Eur. J. 2003, 9, 2595; (e) B. Goldfuss, P. v. R. Schleyer, F. Hampel, J. Am. Chem. Soc. 1996, 118, 12183

[2] P. E. Romero, W. E. Piers, J. Am. Chem. Soc. 2007, 129, 1698.

[3] A. B. Chaplin, J. C. Green, A. S. Weller, J. Am. Chem. Soc. 2011, 133, 13162.

[4] (a) C. Boulho, P. Oulié, L.Vendier, M. Etienne, V. Pimienta, A.Locati, F.Bessac, F. Maseras, D. A. Pantazis, J. E. McGrady, J. Am. Chem. Soc. 2010, 132, 14239; (b) C. Boulho, T. Keys, Y. Coppel, L. Vendier, M. Etienne, A. Locati, F. Bessac, F. Maseras, D. A. Pantazis, J. E. McGrady, Organometallics 2009, 28, 940.

[5] Y. Escudié, C. Dinoi, O. Allen, L. Vendier, M. Etienne, Angew. Chem. Int. Ed. 2012, 51, 2461.

[6] A. Caballero, E. Despagnet-Ayoub, A. Díaz, M. M. Díaz-Requejo, M. E. González-Núñez, R. Mello, B. K. Muñoz, W.-S. Ojo, G. Asensio,M. Etienne, P. J. Pérez., Science 2011, 332, 835.