Molybdenum and Tungsten Monoalkoxide Pyrrolide (MAP) Alkylidene Complexes That Contain a 2,6-Dimesitylphenylimido Ligand
Author(s)Gerber, Laura C. H.; Schrock, Richard Royce; Mueller, Peter
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Molybdenum and tungsten bispyrrolide alkylidene complexes that contain a 2,6-dimesitylphenylimido (NAr*) ligand have been prepared, in which the pyrrolide is the parent pyrrolide or 2,5-dimethylpyrrolide. Monoalkoxide pyrrolide (MAP) complexes were prepared through addition of 1 equiv of an alcohol to the bispyrrolide complexes. MAP compounds that contain the parent pyrrolide (NC[subscript 4]H[– over 4]) are pyridine adducts, while those that contain 2,5-dimethylpyrrolide are pyridine free. Molybdenum and tungsten MAP 2,5-dimethylpyrrolide complexes that contain O-t-Bu, OCMe(CF[subscript 3])[subscript 2], or O-2,6-Me[subscript 2]C[subscript 6]H[subscript 3] ligands were found to have approximately equal amounts of syn and anti alkylidene isomers, which allowed a study of the interconversion of the two employing [superscript 1]H–[superscript 1]H EXSY methods. The K[subscript eq] values ([syn]/[anti]) are all 2–3 orders of magnitude smaller than those observed for a large number of Mo bisalkoxide imido alkylidene complexes, as a consequence of the destabilization of the syn isomer by the sterically demanding NAr* ligand. The rates of interconversion of syn and anti isomers were found to be 1–2 orders of magnitude faster for W MAP complexes than for Mo MAP complexes.
DepartmentMassachusetts Institute of Technology. Department of Chemistry
American Chemical Society (ACS)
Gerber, Laura C. H., Richard R. Schrock, and Peter Müller. “Molybdenum and Tungsten Monoalkoxide Pyrrolide (MAP) Alkylidene Complexes That Contain a 2,6-Dimesitylphenylimido Ligand.” Organometallics 32, no. 8 (April 22, 2013): 2373–2378.
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