Complex chromium and uranyl isocyanates

Bailey, R.A.; Michelsen, T.W.

doi:10.1016/0022-1902(72)80601-8

Cited by 12 publications

(1 citation statement)

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“…Uranium azides have been the subject of extensive research efforts in recent years, largely due to their propensity to extrude dinitrogen, a mode of reactivity that has led to their application in generating uranium nitride species. − In contrast, the isoelectronic cyanate (O-bound, OCN – ) and isocyanate (N-bound, NCO – ) ligands have been the subject of comparatively few studies in the molecular solution-phase chemistry of uranium. − The corresponding conversion of a uranium isocyanate or cyanate to a nitrido complex by loss of CO has not been observed and is furthermore extremely uncommon for any metal. − More broadly, there remains much more to be uncovered about the similarities and differences between azide and cyanate ligands in actinide chemistry.…”

Section: Introductionmentioning

confidence: 99%

Uranium Metallocene Azides, Isocyanates, and Their Borane-Capped Lewis Adducts

et al. 2020

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Uranium(IV) metallocene complexes (Cp iPr4 ) 2 U(N 3 ) 2 (1-N 3 ), (Cp iPr ) 2 U(NCO) 2 (1-NCO), and (Cp iPr4 ) 2 U(OTf) 2 (1-OTf) containing the bulky Cp iPr4 ligand (Cp iPr4 = tetra(isopropyl)cyclopentadienyl) were prepared directly from reactions between (Cp iPr4 ) 2 UI 2 or (Cp iPr4 ) 2 UI and corresponding pseudohalide salts. The mixed-ligand complex (Cp iPr4 ) 2 U(N 3 )(OTf) (1-N 3 -OTf) was isolated after heating a 1:1 mixture of 1-N 3 and 1-OTf. The coordination of 1 equiv B(C 6 F 5 ) 3 to 1-N 3 produced the borane-capped azide(2-NCO) in which the borane-capped cyanate ligand had rearranged to become O-bound to uranium. The reaction of (Cp iPr4 ) 2 UI and NaOCN led to the isolation of the uranium(III) cyanate-bridged "molecular square" [(Cp iPr4 ) 2 U(μ-η 1 :η 1 -OCN)] 4 (3-OCN). Cyclic voltammetry and UV−vis spectroscopy revealed small differences in the electronic properties between azide and isocyanate complexes, while X-ray crystallography showed nearly identical solid-state structures, with the most notable difference being the geometry of borane coordination to the azide in 2-N 3 versus the cyanate in 2-NCO. Reactivity studies comparing 3-OCN to the azide analogue [(Cp iPr4 ) 2 U(μ-η 1 :η 1 -N 3 )] 4 (3-N 3 ) demonstrated significant differences in the chemistry of cyanates and azides with trivalent uranium. A computational analysis of 1-NCO, 1-N 3 , 2-NCO, and 2-N 3 has provided a basis for understanding the energetic preference for specific linkage isomers and the effect of the B(C 6 F 5 ) 3 coordination on the bonding between uranium, azide, and isocyanate ligands.

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