High Oxidation State Multiple Metal−Carbon Bonds

Abstract

Richard R. Schrock received his Ph.D. degree in inorganic chemistry from Harvard in 1971 under the tutelage of John Osborn. After spending 1 year as an NSF postdoctoral fellow at Cambridge University working for Lord Jack Lewis and 3 years at the Central Research and Development Department of E. I. duPont de Nemours and Company, he moved to Massachusetts Institute of Technology in 1975. He became full professor in 1980 and the Frederick G. Keyes Professor of Chemistry in 1989. His interests include the inorganic and organometallic chemistry of high oxidation state, early metal complexes (especially those that contain an alkylidene or alkylidyne ligand), catalysis and mechanisms, the chemistry of high oxidation state dinitrogen and related complexes, and the controlled polymerization of olefins and acetylenes. He has received the ACS Award in Organometallic Chemistry (1985), the Harrison Howe Award of the Rochester ACS section (1990), the ACS Award in Inorganic Chemistry (1996), and an ACS Cope Scholar Award (2001). He has been elected to the American Academy of Arts and Sciences and the National Academy of Sciences. He was Associate Editor of Organometallics for 8 years, has published more than 370 research papers, and has supervised over 100 Ph.D. students and postdocs. (Photograph is reprinted with permission from Richard R. Schrock and L. Barry Hetherington.

A Well-Defined, Silica-Supported Tungsten Imido Alkylidene Olefin Metathesis Catalyst

“…Overall, the data obtained for 2m show that 2 is probably formed as the syn isomer. The structural assignment for 2 is also supported by the EXAFS data (Table 1, Figure S2), which are in agreement with a W atom bound to one nitrogen at 1.734(7) Å, a bond length consistent with an imido ligand, 12 two carbons at 1.873 and 2.16(2) Å, consistent with a neopentylidene and a neopentyl ligands respectively, 5 and one oxygen at 1.95(3) Å, consistent with a siloxy substituent. The EXAFS data are further improved by including three carbons at 3.18(1) Å, assigned to the two quaternary carbons of the neopentyl and neopentylidene ligands in addition to the ipso carbon of the aryl imido group.…”

“…Moreover, they show that the surface complex has the usual pseudo-tetrahedral syn structure, the anti isomer lying 5.7 kcal mol -1 above. 5,25 The main difference between the calculated and experimental structures is the absence of a M···O(Si ) 2 . 26 We have also tested the catalyst (60mg, 3.5%) in a flow reactor at 30°C using propene (17 mL/min; 62 mol propene/mol W/min).…”

New Enantiomerically Pure Alkylimido Molybdenum-Based Alkylidene Complexes. Synthesis, Characterization, and Activity as Chiral Olefin Metathesis Catalysts

“…The oil was dissolved in 10 mL of pentane. This solution was cooled to −30 °C and two crops of bright yellow crystals were collected; yield 1.7 g (2.0 mmol, 42%): 1 Procedure B-Mo(NPhAd) 2 Cl 2 (thf) (4.4 g, 6.4 mmol) was dissolved in 50 mL of ether and the solution was cooled to −78 °C. A solution of PhMe 2 CCH 2 MgCl in ether (11.8 mmol) was added dropwise to the reaction mixture.…”

“…The solids were filtered off and the toluene solution was reduced to 5 mL. White solid was filtered after 48 hours at − 30 °C; yield 461 mg (0.55 mmol, 54%): 1 Variable temperature 1H NMR spectrum of a sample of 7b in toluene-d 8 . Two alkylidene resonances at −70 °C correspond to the two diastereomers of the anti THF adduct.…”

Stereoretentive Olefin Metathesis: An Avenue to Kinetic Selectivity

“…Olefin metathesis has become an indispensable method for the formation of carbon-carbon double bonds, [1][2][3][4][5] finding use in synthetic organic, [6][7][8] biological, [9][10][11] and materials chemistry. [12][13][14] The ubiquity of olefin metathesis as a synthetic tool has been linked to the evolution of catalysts from ill-defined mixtures to well-characterized molecular species based on molybdenum, ruthenium and tungsten.…”