Half-Sandwich Scorpionates as Nitrene Transfer Catalysts

Scorpionate complexes of the middle to late 3d transition metals [(L)M(NCMe)3](BF4)n (M = Mn, Fe, Co, Ni: 1M, L = tris(3,5-dimethylpyrazol-1-yl)methane, TpmMe,Me, n = 2; 2M, L = tris(3-phenylpyrazol-1-yl)methane, TpmPh, n = 2; 3M except 3Mn, L = hydrotris(3,5-dimethylpyrazol-1-yl)borate, [TpMe,Me]−, n = 1; 4M, L = hydrotris(3-phenyl-5-methylpyrazol-1-yl)borate, [TpPh,Me]−, n = 1) were examined as catalysts for styrene aziridination and THF amination using phenyl-N-tosyliodinane as a nitrene donor. [(TpmMe,Me)Fe(NCMe)3](BF4)2 (1Fe) was identified as the most active catalyst, giving nearly quantitative nitrene transfer yields at 5 mol % loadings. The reactivity of 1Fe with a wider range of organic substrates was also explored, and a striking observation was strong selectivity for aromatic rather than benzylic amination for alkylaromatic substrates.