Synthesis of High-Oxidation-State Mo═CHX Complexes, Where X = Cl, CF3, Phosphonium, CN.

Reactions between Z-XCH=CHX where X = Cl, CF3, or CN and Mo(N-t-Bu)(CH-t-Bu)(OHIPT)Cl(PPh2Me) (OHIPT = O-2,6-(2,4,6-i-Pr3C6H2)2C6H3) produce Mo(N-t-Bu)(CHX)(OHIPT)Cl(PPh2Me) complexes. Addition of 2,2'-bipyridyl (Bipy) yields Mo(N-t-Bu)(CHX)(OHIPT)Cl(Bipy) complexes, which could be isolated and structurally characterized. The reaction between Mo(N-t-Bu)(CH-t-Bu)(OHMT)Cl(PPh2Me) (OHMT = O-2,6-(2,4,6-Me3C6H2)2C6H3) and Z-ClCH=CHCl in the presence of Bipy produces a mixture that contains both Mo(N-t-Bu)(CHCl)(OHMT)Cl(PPh2Me) and Mo(N-t-Bu)(CHCl)(OHMT)Cl(Bipy), but the relatively insoluble product that crystallizes from toluene-d 8 is the phosphoniomethylidene complex, [Mo(N-t-Bu)(CHPPh2Me)(OHMT)(Cl)(Bipy)]Cl. The Mo(N-t-Bu)(CHX)(OHIPT)Cl(PPh2Me) complexes (X = Cl or CF3) were confirmed to initiate the stereoselective cross-metathesis between Z-5-decene and Z-XCH=CHX.