A dizirconium trihydride complex supported by a tetradentate carbon-centered tris(aryloxide) ligand [{Na-(dme)}(3){(O3C)Zr}(2)(mu-H)(3)] (2; [O3C] = [(3,5-Bu-t(2)-2-O-C6H2)(3)C](4-)) was prepared by reacting [(O3C)Zr(thf)(3)] (1) with NaBHEt3 in toluene. Exposure of 2 in THE 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)(mu-O2CH)(3)] (3). Treatment of 2 with P-4 in toluene led to formation of [Na(thf)(5)][{Na(thf(2)}(2){(O3C)Zr}(2)(mu-P-3)] (4) and PH3, in which hydrogenation of P4 took place. Complex 2 reacted with Me3SiN3 to afford an azide-bridged cyclotrimer RNa(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.