Stable Analogs of the Uranyl Ion Containing the −NUN− Group

Brown, D. G.; Denning, R.G.

doi:10.1021/ic951386v

Cited by 46 publications

(41 citation statements)

References 38 publications

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“…The PUF 3 molecule has a weak uranium-phosphorus triple bond with a calculated bond length of 2.38 (PW91) or 2.40 (CASPT2; Figure 3). The natural orbital occupation numbers ( Figure 5) give an effective bond order of 2.4 corresponding to a considerably weaker triple bond than in N UF 3 . The terminal U P bond is expected to be weaker than the terminal UN bond as the more diffuse phosphorus orbitals are less effective in forming multiple bonds than nitrogen atomic orbitals.…”

Section: Methodsmentioning

confidence: 99%

“…Most of these investigations have centered on organometallic systems, [1] and molecular complexes containing metal nitride units have been prepared. [2][3][4][5][6] These compounds with U = N linkages and organoimido (An = NR) and phosphinidene (An = PR) groups [7,8] are representative. Matrix-isolation infrared spectroscopy has contributed to the short list of uranium compounds containing triple bonds with discovery of the NUN and CUO molecules and preparation the [NUO] + cation first detected by mass spectrometry.…”

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confidence: 99%

“…[27,28] The smaller UF n molecules have been studied less often, [28,29] but fluorine has demonstrated its ability to facilitate the participation of uranium in important chemical and physical processes. The strong inductive effect of fluorine was central to the stabilization of the first uranium methylidyne complex FCUF 3 , [24] and fluorine should be equally as useful in assisting other even heavier main-group elements to stabilize U VI and to form novel triple bonds to uranium. We report herein a combined experimental and theoretical investigation of uranium-atom reactions with NF 3 and PF 3 , designed to prepare terminal uranium nitride and phosphide functional groups.…”

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Simple NUF₃ and PUF₃ Molecules with Triple Bonds to Uranium

et al. 2008

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The chemical behavior of actinide elements must be understood to manage effectively the many uses of actinide materials in todays world. Considerable interest has developed in recent years in actinide (An) complexes with metalligand multiple bonds. Most of these investigations have centered on organometallic systems, [1] and molecular complexes containing metal nitride units have been prepared. [2][3][4][5][6] These compounds with U = N linkages and organoimido (An = NR) and phosphinidene (An = PR) groups [7,8] are representative. Matrix-isolation infrared spectroscopy has contributed to the short list of uranium compounds containing triple bonds with discovery of the NUN and CUO molecules and preparation the [NUO] + cation first detected by mass spectrometry. [9][10][11][12][13] The common first-row elements carbon, nitrogen, and oxygen form multiple bonds with their 2p valence orbitals, and these bonds are responsible for the chemical properties of many simple compounds, such as HCCH, NN, and O=O. However, heavier main group elements from the second, third, and fourth complete rows of the periodic table are much less inclined to form multiple bonds, and their chemistry markedly reflects this difference.[14] Although the heavier pblock elements are involved in double bonds, such triple bonds are seldom found. On the other hand f elements (lanthanides and actinides) with multiple bonds are not common, and the quest for such compounds with multiple bonds between two actinide metals and between actinide and main-group elements has evolved vigorously with computations leading the former [15][16][17][18][19][20] and synthesis the latter. [1][2][3][4][5][6][7][8] We recently reported the first examples of uranium methylidene and methylidyne molecules using laser-ablated uranium atoms as the reagent. These species include the CH 2 =UH 2 , CH 2 =UHF, CH 2 =UF 2 , HCUF 3 , and FCUF 3 molecules. [21][22][23][24] Analogous methylidene complexes are important reagents in organometallic chemistry, particularly for the early transition metals.[25] Although alkylidyne complexes are not as prevalent, a number of simple Group 6 methylidyne complexes have been prepared through metal-atom reactions with methyl halides. [25,26] Fluorine is a very important element in uranium chemistry because of its role in uranium-isotope separation using gaseous diffusion of the volatile uranium hexafluoride. Accordingly UF 6 has been the subject of considerable experimental and theoretical investigations. [27,28] The smaller UF n molecules have been studied less often, [28,29] but fluorine has demonstrated its ability to facilitate the participation of uranium in important chemical and physical processes. The strong inductive effect of fluorine was central to the stabilization of the first uranium methylidyne complex FCUF 3 , [24] and fluorine should be equally as useful in assisting other even heavier main-group elements to stabilize U VI and to form novel triple bonds to uranium. We report herein a combined experimental and theoretical inves...

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Simple NUF₃ and PUF₃ Molecules with Triple Bonds to Uranium

et al. 2008

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“…However, direct imido analogs of the uranyl ion have remained elusive despite a great deal of effort toward their synthesis. For instance, Denning and co-workers were able to isolate the phosphorane-iminato (UNPR 3 ) and sulfilimine (UNSR 2 ) substituted analogs of uranyl, which are heteroatom approximations to the imido ligand (7)(8)(9). Burns and co-workers were able to synthesize Cp* 2 U(NR) 2 (where R was either Ph or adamantyl and Cp* was C 5 Me 5 ), but with imido groups in a cis configuration (10,11).…”

mentioning

confidence: 99%

“…Burns and co-workers were able to synthesize Cp* 2 U(NR) 2 (where R was either Ph or adamantyl and Cp* was C 5 Me 5 ), but with imido groups in a cis configuration (10,11). The difficulty in isolating a trans-bis(alkyl or aryl imido) complex led Denning to speculate that their isolation was not possible because uranium(VI) is too oxidizing (9).…”

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Synthesis of Imido Analogs of the Uranyl Ion

Hayton

Boncella

Scott

et al. 2005

Science

225

194

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Here we describe the synthesis of two imido analogs of the uranyl ion, UO 2+ 2 , in which the oxygens are replaced by divalent alkyl or aryl nitrogen groups: U(N t Bu) 2 I 2 (THF) 2 (1) and U(NPh) 2 I 2 (THF) 3 (2) (where t Bu is tert -butyl and THF is tetrahydrofuran). Both compounds have been fully characterized by standard analytical techniques, including x-ray crystallography, and the chemical bonding between the metal center and the nitrogen ligands was quantified by using hybrid density functional theory calculations. As expected for a uranyl analog, these complexes exhibit linear N-U-N linkages and very short U-N bonds. In addition, the theoretical calculations show strong involvement of the 5f and 6d electrons in the U-N bonding.

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