Highly Fluorinated Tris(indazolyl)borate Silylamido Complexes of the Heavier Alkaline Earth Metals: Synthesis, Characterization, and Efficient Catalytic Intramolecular Hydroamination

Abstract Heteroleptic silylamido complexes of the heavier alkaline earth elements calcium and strontium containing the highly fluorinated 3‐phenyl hydrotris(indazolyl)borate {F 12 ‐Tp 4Bo, 3Ph } − ligand have been synthesized by using salt metathesis reactions. The homoleptic precursors [Ae{N(SiMe 3 ) 2 } 2 ] (Ae=Ca, Sr) were treated with [Tl(F 12 ‐Tp 4Bo, 3Ph )] in pentane to form the corresponding heteroleptic complexes [(F 12 ‐Tp 4Bo, 3Ph )Ae{N(SiMe 3 ) 2 }] (Ae=Ca ( 1 ); Sr ( 3 )). Compounds 1 and 3 are inert towards intermolecular redistribution. The molecular structures of 1 and 3 have been determined by using X‐ray diffraction. Compound 3 exhibits a Sr ⋅⋅⋅ MeSi agostic distortion. The synthesis of the homoleptic THF‐free compound [Ca{N(SiMe 2 H) 2 } 2 ] ( 4 ) by transamination reaction between [Ca{N(SiMe 3 ) 2 } 2 ] and HN(SiMe 2 H) 2 is also reported. This precursor constitutes a convenient starting material for the subsequent preparation of the THF‐free complex [(F 12 ‐Tp 4Bo, 3Ph )Ca{N(SiMe 2 H) 2 }] ( 5 ). Compound 5 is stabilized in the solid state by a Ca⋅⋅⋅β‐SiH agostic interaction. Complexes 1 and 3 have been used as precatalysts for the intramolecular hydroamination of 2,2‐dimethylpent‐4‐en‐1‐amine. Compound 1 is highly active, converting completely 200 equivalents of aminoalkene in 16 min with 0.50 mol % catalyst loading at 25 °C.