Synthesis and Reactions of Tungsten Alkylidene Complexes That Contain the 2,6-Dichlorophenylimido Ligand

Tungsten alkylidene complexes that contain the 2,6-dichlorophenylimido ligand (NAr Cl ), W(NAr Cl )(CHCMe 3 )(OR F6 ) 2 and W(NAr Cl )(CHCMe 3 )(Biphen)(THP) (OR F6 = OCMe(CF 3 ) 2; Biphen 2- = 3,3‘-di-t-Bu-5,5‘,6,6‘-tetramethyl-1,1‘-biphenyl-2,2‘-diolate; THP = tetrahydropyran), have been prepared from W(NAr Cl )(CHCMe 3 )(OSO 2 CF 3 ) 2 (dme). Reaction of W(NAr Cl )(CHCMe 3 )(OR F6 ) 2 with excess ethylene gave the tungstacyclobutane complex W(NAr Cl )(OR F6 ) 2 (C 3 H 6 ), while reaction of W(NAr Cl )(CHCMe 3 )(OR F6 ) 2 with internal olefins gave the dimer, [W(μ-NAr Cl )(OR F6 ) 2 ] 2 . W(NAr Cl )(CHCMe 3 )(Biphen)(THP) reacted with excess ethylene to give W(NAr Cl )(Biphen)(C 3 H 6 ), which yielded W(NAr Cl )(Biphen)(C 2 H 4 )(THF) upon addition of THF. The tungstacyclopentane complex, W(NAr Cl )(Biphen)(C 4 H 8 ), was formed upon treatment of W(NAr Cl )(Biphen)(C 2 H 4 )(THF) with ethylene. W(NAr Cl )(Biphen)(C 3 H 6 ) decomposed to yield ( inter alia ) the dimeric, heterochiral methylidene complex, [W(NAr Cl )(Biphen)(μ-CH 2 )] 2, which decomposed further to yield homochiral [W(NAr Cl )(Biphen)] 2 (μ-CH 2 CH 2 ). Finally, [W(NAr Cl )(Biphen)] 2 (μ-CH 2 CH 2 ) loses ethylene reversibly to yield [W(NAr Cl )(Biphen)] 2, which could not be isolated in pure form. {W(μ-NAr Cl )[OC(CF 3 ) 2 Me] 2 } 2, W(NAr Cl )(Biphen)(C 3 H 6 ), W(NAr Cl )(Biphen)(C 2 H 4 )(THF), W(NAr Cl )(Biphen)(C 4 H 6 ), [W(NAr Cl )(Biphen)(μ-CH 2 )] 2, and [W(NAr Cl )(Biphen)] 2 (μ-CH 2 CH 2 ) were characterized through X-ray studies.