Compound 2

µ-oxo-bis[tris-tert-butoxysiloxouranium(IV)]

From: The role of bridging ligands in dinitrogen reduction and functionalization by uranium multimetallic complexes

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Synonyms:
  • [{U(OSi(OtBu)3)3}2(μ-O)]

Compound data: 1H NMR

Compound data: 13C NMR

Compound data: Crystallographic data

Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.

A cold yellow suspension of IMesN2O (184.7 mg, 0.53 mmol, 1 eq) in THF (6 mL) was added to a cold solution (-80 °C) of complex [U(OSi(OtBu)3)3]2, 1 (1.09 g, 0.53 mmol, 1 eq) in THF (6 mL). N2 evolution was observed. The solution was allowed to react at -80°C for 4 h. Monitoring the reaction mixture by 1H NMR in THF-d8 shows that the reaction is complete after 4 hours at -80 °C and some solid has formed. The resulting suspension was taken to dryness and the solid residue was washed several times with cold (-40°C) toluene (2mL), until complete removal of the IMes carbene formed during the reaction, to afford [{U(OSi(OtBu)3)3}2(μ-O)], 2, as a pink solid (0,87 g, 79 % yield). X-ray suitable crystals were obtained by leaving standing a 0.005 M solution of 2 in toluene at -40 °C overnight. 1H NMR of the solid (400 MHz, tol-d8, 298 K): δ (ppm) = 0.49 (s, CH3 terminal siloxide 13C NMR of the solid (400 MHz, tol-d8, 298 K): δ (ppm) = 70.16 (s, (C(CH3)3),), δ (ppm) = 25.97 (s, (C(CH3)3)) Anal. Calcd for 2 C72H162O25Si6U2: C, 41.72; H, 7.88; N, 0.00. Found: C, 41.46; H, 7.77; N, 0.00. When the reaction is carried out at higher temperatures, a larger number of by-products are formed and the yield in complex 2 is significantly reduced. Complex 2 is stable in THF and toluene solution at room temperature for, respectively, 24 and 6 hours, but decomposes slowly over time to afford unidentified species and [U(OSi(OtBu)3)4]. The decomposition is complete after 20-30 days.

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