10.1021/acs.organomet.5b00703.s002
Maryam Yousif
Maryam
Yousif
Daniel
J. Tjapkes
Daniel
J.
Tjapkes
Richard L. Lord
Richard L.
Lord
Stanislav Groysman
Stanislav
Groysman
Catalytic Formation of Asymmetric Carbodiimides at
Mononuclear Chromium(II/IV) Bis(alkoxide) Complexes
American Chemical Society
2015
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 00:00:00
Dataset
https://acs.figshare.com/articles/dataset/Catalytic_Formation_of_Asymmetric_Carbodiimides_at_Mononuclear_Chromium_II_IV_Bis_alkoxide_Complexes/2118430
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>.