Zirconium Hydride Complex Supported by a Tetradentate Carbon-Centered Tripodal Tris(aryloxide) Ligand: Synthesis, Structure, and Reactivity

A dizirconium trihydride complex supported by a tetradentate carbon-centered tris(aryloxide) ligand [{Na(dme)}3{(O3C)Zr}2(μ-H)3] (2; [O3C] = [(3,5-(t)Bu2-2-O-C6H2)3C](4-)) was prepared by reacting [(O3C)Zr(thf)3] (1) with NaBHEt3 in toluene. Exposure of 2 in THF to CO2 (1 atm) resulted in facile insertion of CO2 into Zr-H bonds, yielding a formate complex [{Na(thf)2}3{(O3C)Zr}2(μ-O2CH)3] (3). Treatment of 2 with P4 in toluene led to formation of [Na(thf)5][{Na(thf)2}2{(O3C)Zr}2(μ-P3)] (4) and PH3, in which hydrogenation of P4 took place. Complex 2 reacted with Me3SiN3 to afford an azide-bridged cyclotrimer [{Na(thf)2}{(O3C)ZrN3(thf)}]3 (5) with concomitant liberation of Me3SiH. The molecular structures of these complexes 2-5 have been determined by X-ray diffraction analyses.