η3‑Silaallyl/Alkenylsilyl Molybdenum Complex: Synthesis, Structure, and Reactivity toward Primary Amines To Form Mo–N–Si Three-Membered Cyclic Complexes

The new η3-silaallyl/alkenylsilyl molybdenum complex Cp*Mo­(CO)2(η3-Ph2SiCHCMe2) (3) was synthesized by the reaction of Cp*Mo­(CO)2(py)­Me with Ph2HSiCHCMe2. Reactions of 3 with primary amines RNH2 (R = tBu, iPr, Et) gave Mo–N–Si three-membered cyclic complexes Cp*Mo­(CO)2(κ2-N,Si-RHNSiPh2) (5a, R = tBu; 5b, R = iPr; 5c, R = Et) with elimination of isobutene. In NMR tube reactions using iPrNH2 and EtNH2, the Mo–N–Si–C four-membered cyclic complexes Cp*Mo­(CO)2(κ2-N,C-RHNSiPh2CHiPr) (4b, R = iPr; 4c, R = Et) were observed as intermediates leading to 5b and 5c, respectively. Complex 4c was successfully isolated in a preparative reaction. The molecular structures of 3, 4c, and 5b were determined by X-ray crystal analyses. Interestingly, the contribution of silylene character was suggested for the SiPh2 moiety of 5b from the X-ray structure. The reaction of 5b with MeOH gave the dinuclear complex Cp*­(CO)2Mo­(μ-OMe)­(μ-H)­Mo­(CO)2Cp* as a major product.