REDUCTION OF MOLYBDENUM IMIDO ALKYLIDENE COMPLEXES IN THE PRESENCE OF OLEFINS TO GIVE MOLYBDENUM(IV) COMPLEXES

Mo(CH-t-Bu)(NAr)[OCMe(CF3)2]2 (1a) (Ar = 2,6-diisopropylphenyl) reacts with excess vinyltrimethylsilane to give Mo(NAr)[OCMe(CF3)2]2(CH2 = CHSiMe3) (2). Complex 2 reacts with trimethylphosphine, 2-butyne, and excess ethylene to give Mo(NAr)[OCMe(CF3)2]2(PMe3)2 (3), Mo(NAr)[OCMe(CF3)2]2(MeC = CMe) (4), or Mo(NAr)[OCMe(CF3)2]2(C4H8) (8), respectively. Complex 4 reacts with PMe3 to give Mo(NAr)[OCMe(CF3)2]2(MeC = CMe)(PMe3) (5), and 8 reacts with PMe3 to give Mo(NAr)(OCMe(CF3)2]2(CH2 = CH2)(PMe3) (9). Metallacycle Mo(CH2CH2CH2)(NAr)[OCMe(CF3)2]2 (6) decomposes in the presence of excess ethylene to form 8 and reacts with trimethylphosphine to give Mo(CH2)(NAr)[OCMe(CF3)2]2(PMe3) (7). Mo(CH-t-Bu)(NAr)(O-t-Bu)2 (1b) reacts with excess ethylene to give Mo(CH2CH2CH2)(NAr)(O-t-Bu)2 (10), which reacts with trimethylphosphine to give Mo(CH2)(NAr)(O-t-Bu)2(PMe3) (11). 10 decomposes to [Mo(NAr)(O-t-Bu)2]2 (12; C2/c, a = 14.772 (6) angstrom, b = 15.470 (4) angstrom, c = 10.625 (8) angstrom, beta = 104.62 (3)-degrees, Z = 4, M(r) = 834.88, rho = 1.276 g/cm3, mu = 5.99 cm-1, R1 = 0.035, R2 = 0.047). 12 is an imido-bridged dimer that is believed to form upon coupling of methylene ligands in two Mo(NAr)(CH2)(O-t-Bu)2 complexes.