Syntheses of Molybdenum Adamantylimido and -Butylimido Alkylidene Chloride Complexes Using HCI and Diphenylmethylphosphine.

Reactions between Mo(N--Bu)(CH--Bu) or Mo(NAdamantyl)(CHCMePh) and 3 equiv of HCl in the presence of 1 equiv of PPhMe yield Mo(NR)(CHR')(PPhMe)Cl complexes, from which Mo(NR)(CHR')(PPhMe)(OAr)Cl complexes (OAr = a 2,6-terphenoxide) can be prepared. The Mo(NR)(CHR')(PPhMe)(OAr)Cl complexes were evaluated as cross-metathesis catalysts between cyclooctene and -1,2-dichloroethylene. The efficiencies of the test reaction for complexes in which OAr = OTPP, OHMT, OHIPT, or OHTBT (where OTPP is 2,3,5,6-tetraphenylphenoxide, OHMT is hexamethylterphenoxide, OHIPT is hexaisopropylterphenoxide, and OHTBT is hexa-butylterphenoxide) maximize when OAr is OHMT or OHIPT. Mo(N--Bu)(CH--Bu)(PPhMe)Cl is essentially inactive for the reaction between cyclooctene and -1,2-dichloroethylene. X-ray structural studies were carried out on Mo(NAd)(CHCMePh)(PPhMe)Cl, Mo(N--Bu)(CH--Bu)(PPhMe)(OHMT)Cl, Mo(NAd)(CHCMePh)(Cl)(OHTBT)(PMe), and Mo(NAd)(CHCMePh)(PMe)(Cl), the product of the reaction between Mo(NAd)(CHCMePh)(Cl)(OHTBT)(PMe) and 0.5 equiv of water.