Reductive disproportionation of nitric oxide mediated by low-valent uranium

Abstract

The reductive disproportionation of nitric oxide (1 atm) is mediated by the bulky UIII aryloxide [UIII(OArAd,Ad,Me)3] (1) (Ad,Ad,MeArO = O-C6H2-2,6-Ad-4-Me) to form the UV terminal oxo species [(Ad,Ad,MeArO)3UV(O)] (2) and N2O, as confirmed by single crystal X-ray diffraction and GC-MS measurements.

A Combined Experimental and Theoretical Study of the Versatile Reactivity of an Oxocerium(IV) Complex: Concerted Versus Reductive Addition

“…Metalmediated disproportionation of NO to give N 2 Oi sw ell documented. [15] It should be noted that the above-mentioned reactions with CO, SO 2 ,a nd NO are unique for the Ce IV -oxo complex. No reactionw as found between the non-oxo Ce IV complexes, such as [Ce(L OEt ) 2 X 2 ]( X= Cl À ,N O 3 À ), and CO, SO 2 ,o rN O under the same conditions, indicating that the Ce=Om oiety is essential for the reductiveinsertion reactions.…”

CO2 Activation with Formation of Uranium Carbonate Complexes in a Closed Synthetic Cycle

“…The coordination environment at the uranium center is best described as (distorted) trigonal pyramidal, with an average oxygen atom features a U−O bond length of 1.904 Å, approximately 0.1 Å longer than the corresponding bond determined for the uranium(V) precursor 2 (Table 1). 39 The The molecular structure of tetravalent 4a exhibits a trigonalpyramidal geometry, similar to pentavalent 2, with only slight differences in the bond lengths and angles, reflecting the oneelectron reduction of the metal center (Figure 2). The U−O bond length of the terminal oxo moiety is 1.862(3) Å, which is 0.05 Å longer in comparison to the uranium(V) complex 2 and compares well with values of other uranium(IV) oxo complexes in the literature, ranging from 1.860(3) to 1.916(6) Å.…”

“…The pentavalent oxo species [( Ad,Ad,Me ArO) 3 U V (O)] (2), previously reported and isolated after oxidation by N 2 O or NO, 39 proved to be inert toward CO 2 . Consequently, 2 was reduced with the strong reductant KC The molecular structure of 3 reveals an infinite 1D polymeric chain with the potassium cations acting as linkers between the uranium units.…”

“…37,38 On the basis of the few known examples, it appears that terminal oxo formation and CO 2 reactivity of uranium complexes benefit from sterically demanding, monodentate systems, such as ( t Bu) 3 SiOH 37 and Ad,Ad,Me ArOH. 39 These bulky ligands can prevent the formation of dinuclear compounds yet provide the necessary flexibility for the changes in geometry during the formation of terminal oxo or carbonate complexes. In the context of this study, we further investigated monodentate aryloxide ligands in order to investigate the role of the compounds' geometric flexibility for CO 2 activation.…”

The synthesis and versatile reducing power of low-valent uranium complexes

“…134,135 Finally, reaction of uranium tris(aryloxide) U(O-2,6-Ad 2-4-MeC6H2)3 with excess NO led to formation of the uranium(V) oxo complex U(O)(O-2,6-Ad 2-4-MeC 6H2)3 and N2O; this reductive disproportionation process was proposed to occur via a uranium(IV) η 1 -ONNO − intermediate. 136 The same oxo complex was isolated by reaction of U(O-2,6-Ad 2-4-MeC6H2)3 with N2O. 136…”