164468-53-5Relevant academic research and scientific papers
Synthesis, Structure, and Properties of Homoleptic 1-Oxa-1,3-diene Molybdenum and Tungsten Complexes
Schmidt, Thomas,Neis, Stephan,Goddard, Richard
, p. 315 - 325 (2007/10/02)
Homoleptic tris(1-oxa-1,3-diene)molybdenum and tungsten complexes are formed as yellow, crystalline compounds in 54-80percent isolated yield on treatment of the corresponding β-unsubstituted α,β-unsaturated ketones with W(CO)3(CH3CH2CN)3 or (η6-C6H6)Mo(CO)3 in refluxing hexane.Reaction of these oxadienes with (η6-C6H5CH3)2Mo in tetrahydrofuran or n-hexane provides a new high yield route to homoleptic molybdenum complexes that are otherwise difficult to prepare.X-ray crystal structure analyses of two air-stable, isomeric tungsten complexes reveal a significant contribution of a ?2,η2-bonding mode in the coordinated oxadiene moieties.Under reaction conditions that allow the platinum catalyzed hydrogenation of phenyl substituents in these ligands, the coordinated oxadiene fragments are inert, thus demonstrating an unprecedented chemoselectivity in the hydrogenation of aryl-substituted enones.On the other hand, the complexes are labile enough to catalyze the cyclotrimerization of alkynes such as methyl propiolate. - Keywords: Oxadiene Complex, Molybdenum, Tungsten, X-Ray, Selective Hydrogenation
