Yousif, Maryam Tjapkes, Daniel J. Lord, Richard L. Groysman, Stanislav Catalytic Formation of Asymmetric Carbodiimides at Mononuclear Chromium(II/IV) Bis(alkoxide) Complexes Herein we report the synthesis of Cr imido complexes in bis­(alkoxide) ligand environments and their nitrene transfer reactivity with isocyanides. The reaction of Cr<sub>2</sub>(OR)<sub>4</sub> (OR = OC<sup><i>t</i></sup>Bu<sub>2</sub>Ph) with bulky aryl or alkyl azide results in the formation of the trigonal-planar Cr­(IV) mono­(imido) complexes Cr­(OR)<sub>2</sub>(NR<sup>1</sup>), whereas less bulky aryl azides form the Cr­(VI) bis­(imido) complexes Cr­(OR)<sub>2</sub>(NR<sup>1</sup>)<sub>2</sub>. Cr­(IV) mono­(imido) complexes undergo facile reaction with 1 equiv of 2,6-dimethylphenyl isocyanide (CNR<sup>2</sup>) to form the corresponding carbodiimides R<sup>1</sup>NCNR<sup>2</sup>. In contrast, no reaction of Cr­(OR)<sub>2</sub>(NR<sup>1</sup>)<sub>2</sub> complexes with CNR<sup>2</sup> is observed. The reaction of Cr­(OR)<sub>2</sub>(NR<sup>1</sup>) with excess isocyanide leads to the isolation of the Cr­(II) complex Cr­(OR)<sub>2</sub>(CNR<sup>2</sup>)<sub>4</sub>, along with the observation of the anticipated carbodimide product. Cr­(OR)<sub>2</sub>(CNR<sup>2</sup>)<sub>4</sub>, which can also be obtained by treating Cr<sub>2</sub>(OR)<sub>4</sub> with 4 equiv of isocyanide, reacts with azides N<sub>3</sub>R<sup>1</sup> (R<sup>1</sup> = adamantyl, mesityl) to produce the respective carbodiimides. Catalytic formation of carbodiimides R<sup>1</sup>NCNR<sup>2</sup> is observed from the mixtures of azides R<sup>1</sup>N<sub>3</sub> (R<sup>1</sup> = mesityl, 2,6-diethylphenyl, 2-isopropylphenyl, adamantyl) and several different aryl isocyanides CNR<sup>2</sup> using 2.5 mol % of Cr<sub>2</sub>(OR)<sub>4</sub>. carbodiimides R 1NCNR;nitrene transfer reactivity;aryl azides form;R 1;alkyl azide results;azides R 1N;aryl isocyanides CNR 2;Cr imido complexes;azides N 3R 2015-10-26
    https://acs.figshare.com/articles/dataset/Catalytic_Formation_of_Asymmetric_Carbodiimides_at_Mononuclear_Chromium_II_IV_Bis_alkoxide_Complexes/2118430
10.1021/acs.organomet.5b00703.s002