| Abstrakt: |
Chiral tungsten(II) η1-imine complexes [Tp(CO)(PhC&tbd1;CMe)W(NH&dbd;CRR)]+ (Tp = hydridotris(3,5-dimethylpyrazolyl)borate) have been prepared by oxidation of the corresponding amido complexes Tp(CO)(PhC&tbd1;CMe)W(NHCHRR) (R/R = Ph/Ph, Ph/Me, Me/Et, and H/CHMePh) with elemental iodine. These oxidations also result in formation of amine complexes which have been independently synthesized. Oxidation in the presence of a weak base suppresses amine formation. However, when R = Ph, deprotonation of the imine product forms the neutral azavinylidene complex Tp(CO)(PhC&tbd1;CMe)W(N&dbd;CRR). Protonation of the azavinylidene complex provides a clean route to the desired imine complex. Crystal structures of a representative complex from each category of nitrogen donor ligand have been determined: cationic imine complex [Tp(CO)(PhC&tbd1;CMe)W(NH&dbd;CMeEt)][BAr4] (2a), cationic amine complex [Tp(CO)(PhC&tbd1;CMe)W(NH2CH2CHMePh)][I3] (4d), neutral amido complex Tp(CO)(PhC&tbd1;CMe)W(NHCHMeEt) (1a), and neutral azavinylidene complex Tp(CO)(PhC&tbd1;CMe)W(N&dbd;CMePh) (3b). |
