Syntheses and Structures of Molybdenum Imido Alkylidene Pyrrolide and Indolide Complexes

An X-ray structural study of Mo(NAd)(CHCMe 2 Ph)(2,5-Me 2 NC 4 H 2 ) 2 ( 1; Ad = 1-adamantyl) reveals it to contain one η 1 -2,5-Me 2 NC 4 H 2 ring and one η 5 -2,5-Me 2 NC 4 H 2 ring. The structures of Mo(NAr)(CHCMe 2 Ph)(pyrrolide) 2 (Ar = 2,6- i -Pr 2 C 6 H 3 ) complexes that contain 2,3,4,5-tetramethylpyrrolides, 2,5-diisopropylpyrrolides, or 2,5-diphenylpyrrolides are analogous to that of 1 . In contrast, Mo(NAr)(CH 2 CMe 2 Ph)(indolide) 2 ( 6 ) was shown to contain two η 1 -bound indolides. Monohexafluoro- t -butoxide pyrrolide (MAP) species can be prepared, either through addition of one equiv of Me(CF 3 ) 2 COH to a bispyrrolide or through reactions between the lithium pyrrolide and the bishexafluoro- t -butoxide. A trimethylphosphine adduct of a bispyrrolide, Mo(NAd)(CHCMe 2 Ph)(η 1 -NC 4 H 4 ) 2 (PMe 3 ), has been prepared and structurally characterized, while a PMe 3 adduct of MAP hexafluoro- t -butoxide species was found to have PMe 3 bound approximately trans to the pyrrolide. This adduct serves as a model for the structure of the initial olefin adduct in olefin metathesis.