Molybdenum Monoaryloxide Pyrrolide Alkylidene Complexes That Contain Mono-ortho-substituted Phenyl Imido Ligands

Abstract

Monaryloxide pyrrolide (MAP) molybdenum imido alkylidene complexes of the type Mo(NArX)(CHCMe2R)(Me2Pyr)(OR′) (Me2Pyr = 2,5-dimethylpyrrolide) have been prepared in which NArX is an ortho-substituted phenylimido group (X = Cl (NArCl), CF3 (NArCF3), i-Pr (NAriPr), t-Bu (NArtBu), mesityl (NArM), or TRIP (TRIP = triisopropylphenyl; NArT)) and OR′ = O-2,3,5,6-(C6H5)4C6H (OTPP), O-2,6-(2,4,6-Me3C6H2)2C6H3 (OHMT), or O-2,6-(2,4,6-i-Pr3C6H2)2C6H3 (OHIPT). The object was to explore to what extent relatively “large” NArM or NArT ligands would alter the performance of MAP catalysts in reactions that have been proposed to depend upon the relative size of the imido and OR′ groups. Preliminary studies employing the ring-opening metathesis polymerization of 5,6-dicarbomethoxynorbornadiene as a measure of selectivity suggest that a single phenylimido ortho substituent, even in an NArM or NArT group, does not produce any unique behavior and that the outcome of the ROMP reaction correlates with the overall relative size o...