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Synthesis and characterization of an f-block terminal parent imido [U═NH] complex: a masked uranium(IV) nitride.

King DM, McMaster J, Tuna F, McInnes EJ, Lewis W, Blake AJ, Liddle ST - J. Am. Chem. Soc. (2014)

Bottom Line: Treatment of 2c (M = K) with 2 equiv of 15-crown-5 ether (15C5) afforded the uranium terminal parent imido complex [U(Tren(TIPS))(NH)][K(15C5)2] (3c), which can also be viewed as a masked uranium(IV) nitride.The uranium-imido linkage was found to be essentially linear, and theoretical calculations suggested σ(2)π(4) polarized U-N multiple bonding.Attempts to oxidize 3c to afford the neutral uranium terminal parent imido complex [U(Tren(TIPS))(NH)] (4) resulted in spontaneous disproportionation to give 1 and the uranium-nitride complex [U(Tren(TIPS))(N)] (5); this reaction is a new way to prepare the terminal uranium-nitride linkage and was calculated to be exothermic by -3.25 kcal mol(-1).

View Article: PubMed Central - PubMed

Affiliation: School of Chemistry, University of Nottingham , University Park, Nottingham NG7 2RD, U.K.

ABSTRACT
Deprotonation of [U(Tren(TIPS))(NH2)] (1) [Tren(TIPS) = N(CH2CH2NSiPr(i)3)3] with organoalkali metal reagents MR (M = Li, R = Bu(t); M = Na-Cs, R = CH2C6H5) afforded the imido-bridged dimers [{U(Tren(TIPS))(μ-N[H]M)}2] [M = Li-Cs (2a-e)]. Treatment of 2c (M = K) with 2 equiv of 15-crown-5 ether (15C5) afforded the uranium terminal parent imido complex [U(Tren(TIPS))(NH)][K(15C5)2] (3c), which can also be viewed as a masked uranium(IV) nitride. The uranium-imido linkage was found to be essentially linear, and theoretical calculations suggested σ(2)π(4) polarized U-N multiple bonding. Attempts to oxidize 3c to afford the neutral uranium terminal parent imido complex [U(Tren(TIPS))(NH)] (4) resulted in spontaneous disproportionation to give 1 and the uranium-nitride complex [U(Tren(TIPS))(N)] (5); this reaction is a new way to prepare the terminal uranium-nitride linkage and was calculated to be exothermic by -3.25 kcal mol(-1).

No MeSH data available.


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Structure of 3c (40% displacement ellipsoids;non-imidoH atoms and minor disorder components omitted for clarity).
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fig2: Structure of 3c (40% displacement ellipsoids;non-imidoH atoms and minor disorder components omitted for clarity).

Mentions: The solid-statestructure of 3c was determined byX-ray crystallography to confirm the separated ion pair formulation(Figure 2). The U1–N5 bond length wasdetermined to be 2.034(3) Å, which most likely reflects the anionicnature of [U(TrenTIPS)(NH)]− in partcounteracting the abstraction of an alkali metal to give a terminalU=NH linkage. However, the U–Nimido distancein 3c is 0.2 Å shorter than the U–NH2 bond length in 1,6b is only 0.07 Å longer than the sum of the double additive covalentradii of uranium and nitrogen,15 and compareswell to terminal U(IV)=NR bond lengths (1.95–2.01 Å).16 The U–Namide distances in 3c are indistinguishable from those of 2a–e, but the anionic and terminal nature of [U(TrenTIPS)(NH)]− in 3c is apparent upon inspectionof the U–Namine bond, which is trans to the imidogroup and notably longer [2.749(3) Å] than the analogous distancesin 2a–e [av 2.674(4) Å]. Theimido H atom was located in the Fourier transform difference map andwas refined with restraints, giving a U=N–H angle of172(3)°.


Synthesis and characterization of an f-block terminal parent imido [U═NH] complex: a masked uranium(IV) nitride.

King DM, McMaster J, Tuna F, McInnes EJ, Lewis W, Blake AJ, Liddle ST - J. Am. Chem. Soc. (2014)

Structure of 3c (40% displacement ellipsoids;non-imidoH atoms and minor disorder components omitted for clarity).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4353020&req=5

fig2: Structure of 3c (40% displacement ellipsoids;non-imidoH atoms and minor disorder components omitted for clarity).
Mentions: The solid-statestructure of 3c was determined byX-ray crystallography to confirm the separated ion pair formulation(Figure 2). The U1–N5 bond length wasdetermined to be 2.034(3) Å, which most likely reflects the anionicnature of [U(TrenTIPS)(NH)]− in partcounteracting the abstraction of an alkali metal to give a terminalU=NH linkage. However, the U–Nimido distancein 3c is 0.2 Å shorter than the U–NH2 bond length in 1,6b is only 0.07 Å longer than the sum of the double additive covalentradii of uranium and nitrogen,15 and compareswell to terminal U(IV)=NR bond lengths (1.95–2.01 Å).16 The U–Namide distances in 3c are indistinguishable from those of 2a–e, but the anionic and terminal nature of [U(TrenTIPS)(NH)]− in 3c is apparent upon inspectionof the U–Namine bond, which is trans to the imidogroup and notably longer [2.749(3) Å] than the analogous distancesin 2a–e [av 2.674(4) Å]. Theimido H atom was located in the Fourier transform difference map andwas refined with restraints, giving a U=N–H angle of172(3)°.

Bottom Line: Treatment of 2c (M = K) with 2 equiv of 15-crown-5 ether (15C5) afforded the uranium terminal parent imido complex [U(Tren(TIPS))(NH)][K(15C5)2] (3c), which can also be viewed as a masked uranium(IV) nitride.The uranium-imido linkage was found to be essentially linear, and theoretical calculations suggested σ(2)π(4) polarized U-N multiple bonding.Attempts to oxidize 3c to afford the neutral uranium terminal parent imido complex [U(Tren(TIPS))(NH)] (4) resulted in spontaneous disproportionation to give 1 and the uranium-nitride complex [U(Tren(TIPS))(N)] (5); this reaction is a new way to prepare the terminal uranium-nitride linkage and was calculated to be exothermic by -3.25 kcal mol(-1).

View Article: PubMed Central - PubMed

Affiliation: School of Chemistry, University of Nottingham , University Park, Nottingham NG7 2RD, U.K.

ABSTRACT
Deprotonation of [U(Tren(TIPS))(NH2)] (1) [Tren(TIPS) = N(CH2CH2NSiPr(i)3)3] with organoalkali metal reagents MR (M = Li, R = Bu(t); M = Na-Cs, R = CH2C6H5) afforded the imido-bridged dimers [{U(Tren(TIPS))(μ-N[H]M)}2] [M = Li-Cs (2a-e)]. Treatment of 2c (M = K) with 2 equiv of 15-crown-5 ether (15C5) afforded the uranium terminal parent imido complex [U(Tren(TIPS))(NH)][K(15C5)2] (3c), which can also be viewed as a masked uranium(IV) nitride. The uranium-imido linkage was found to be essentially linear, and theoretical calculations suggested σ(2)π(4) polarized U-N multiple bonding. Attempts to oxidize 3c to afford the neutral uranium terminal parent imido complex [U(Tren(TIPS))(NH)] (4) resulted in spontaneous disproportionation to give 1 and the uranium-nitride complex [U(Tren(TIPS))(N)] (5); this reaction is a new way to prepare the terminal uranium-nitride linkage and was calculated to be exothermic by -3.25 kcal mol(-1).

No MeSH data available.


Related in: MedlinePlus