Half-sandwich and mixed-ring uranium complexes

Berthet, Jean‐Claude; Maréchal, Jean‐François Le; Ephritikhine, Michel

doi:10.1016/0022-328x(94)87111-6

Cited by 20 publications

(17 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This was a major obstacle in the development of the chemistry of mono(cyclooctatetraenyl) uranium compounds for a long time 13. However, this situation favored the design of several [U(COT)X 2 ] complexes (X = I,14 BH 4 ,12 NEt 2 15) which were useful precursors for the synthesis of alkyl,14b alkoxide,16 or thiolate17 derivatives. …”

Section: Resultsmentioning

confidence: 99%

Synthesis of Organouranium(IV) Triflates from U(OTf)4 or from Alkyl or Amide Precursors

Berthet

Nierlich

Ephritikhine

2002

Eur. J. Inorg. Chem.

Self Cite

View full text Add to dashboard Cite

The uranium(IV) triflate [U(OTf)4] (1) (OTf = OSO2CF3) gives stable adducts with Lewis bases, such as [U(OTf)4(py)] (2) (py = pyridine). The crystal structure of a solvate of [U(OTf)4(OPPh3)3] (3), which exhibits a bidentate OTf group, has been determined. Substitution of the triflate ligands of 1 with LiNEt2, Kacac (acac = MeCOCHCOMe), KCp (Cp = η‐C5H5), and K2COT (COT = η‐C8H8) has led to the formation of [U(NEt2)4], [U(acac)4], [U(Cp)3(OTf)] (4), and [U(COT)(OTf)2(py)] (5), respectively. However, the bis(cyclopentadienyl) compounds [U(Cp*)2(OTf)2] (6) (Cp* = η‐C5Me5) and [U(Cp)2(OTf)2(py)] (7) could not be prepared from 1. Complexes 4−7 have been isolated in good yields from the protonolysis reactions of the corresponding alkyl or amide precursors by means of pyridinium triflate. Compound 5 has also been prepared by treating [U(COT)2] with either [pyH][OTf] or 1 in pyridine. The crystal structures of [U(Cp)2(OTf)2(py)2] (8) and [U(COT)(OTf)2(OPPh3)2]·0.5py (9) have been determined.

show abstract

Section: Resultsmentioning

confidence: 99%

Synthesis of Organouranium(IV) Triflates from U(OTf)4 or from Alkyl or Amide Precursors

Berthet

Nierlich

Ephritikhine

2002

Eur. J. Inorg. Chem.

Self Cite

View full text Add to dashboard Cite

show abstract

“…This group permitted to isolate unique examples of monocyclooctatetraene uranium alkyl compounds, [U(C 8 H 8 )(CH 2 SiMe 3 ) 2 (hmpa)] and [Li(THF) 3 ][U(C 8 H 8 )(CH 2 SiMe 3 ) 3 ], while other alkyl derivatives were found to decompose into [U(C 8 H 8 ) 2 ]. 32 For this reason, reactions of UO 2 X 2 (X = I, OTf) and LiCH 2 SiMe 3 were considered.…”

Section: Polynuclear Uranyl(v) Complexes With O=u=o→m Interactions (M...mentioning

confidence: 99%

Synthesis and crystal structure of pentavalent uranyl complexes. The remarkable stability of UO2X (X = I, SO3CF3) in non-aqueous solutions

et al. 2009

Self Cite

View full text Add to dashboard Cite

The reaction of [UO(2)I(2)(THF)3] with KC(5)R(5) (R = H, Me) or K(2)C(8)H(8) in pyridine gave crystals of [{UO(2)(py)(5)}{KI2(py)2}]. (1), which were desolvated under vacuum into pulverulent [UO(2)(py)2.2KI2] (2).Similar reactions with [UO2(OTf)2] afforded [UO2(py)2.3K(OTf)2] (3) as a powder and crystals of [{UO(2)(py)(5)}2{K(3)(OTf)(5)}. py]. (4.py), which were also obtained together with crystals of [{UO2(py)5}2{K(OTf)2(py)2}][OTf] py (5. py) by treating [UO2(OTf)2] with KC(4)Me(4)P. Crystals of 6. py, the thallium analogue of 5. py, were isolated from the reaction of [UO2(OTf)2] and TlC5H5. Treatment of[UO2I2(THF)3] with LiCH2SiMe3 in pyridine afforded crystals of [{UO(2)(py)5}{LiI(py)2}][I] (7) while[UO(2)(OTf)2] reacted with the alkyllithium reagent in acetonitrile to give crystals of [{UO2(py)5}{Li2(OTf)3}]. (8) in pyridine. The crystal structures of 1, 4. py, 5. py, 6. py, 7 and 8 revealed the presence of U=O-->M interactions (M = Li, K, Tl), and the rich diversity of these structures, from dinuclear (7) to 3D polymeric (4), is related to the distinct coordination numbers of the M+ ion and ligation modes of the bridging iodide and triflate ligands as well as the presence of U=O-->M interactions. The mononuclear complexes [UO2(OTf)(THF)n] (9) and [UO2(OTf)(Et2O)0.5] (10) were respectively obtained by reaction of [UO2(OTf)2] with KC5R5 in THF or LiCH2SiMe3 in Et2O, and were transformed into [UO(2)(OTf)(py)2] (11) in pyridine. Treatment of [UO(2)I(2)(THF)3] with TlC5H5 inpyridine afforded crystals of [UO2(py)5][I]. py (12. py) which were desolvated under vacuum into the powder of [UO(2)I(py)2.5] (14). The same reaction in THF gave [UO2I(THF)2.7] (13) in powder form.Crystals of [UO(2)(CyMe4BTBP)(py)][OTf]. 1.5py (15. 1.5py) and the powder of [UO2I(CyMe4BTBP)](16) were obtained by treating [UO(2)(CyMeBTBP)X2] (X= OTf, I) with KC5Me5 or TlC5H5,respectively. The uranyl(V) chloride and nitrate compounds [UO(2)Cl(py)3] (17) and [UO2(NO3)(py)3] (18)were prepared by reaction of the uranyl(VI) precursors with TlC5H5 in pyridine; complex 18 was also obtained by treating 13 with TlNO3. Crystals of the neutral mononuclear complex [UO(2)(OTf)(py)4] (19)were isolated from reaction of [UO(2)(OTf)2] with Me3SiC5H5 in acetonitrile. Similar reaction with [UO(2)Cl(2)(THF)2]2 in pyridine gave crystals of [UO(2)Cl(2)(py)3]. The crystal structures of 12 py, 15. 1.5py and 19 were determined; the structure of 15 was compared with that of the uranyl(VI) counterpart. All the uranyl(V) compounds are remarkably stable in pyridine solution; the IR absorption at 816 cm-1 is attributed to the v (asym)(U=O) of the ubiquitous [UO(2)(py)(5)]+ species.

show abstract

“…Therefore, it is not surprising that the earliest attempts to prepare homoleptic actinide alkyl complexes often led to the isolation of mixtures of thermally unstable products which proved difficult to characterize. , Numerous methodologies have subsequently been employed to overcome the problem of stabilizing homoleptic actinide σ-alkyl derivatives, including the preparation of anionic alkyl complexes which possess high coordination numbers at the metal center, the use of phosphine ligands to prepare base-stabilized alkyl complexes ThR 4 (Me 2 PCH 2 CH 2 PMe 2 ) (R = Me, CH 2 Ph), and the use of the sterically demanding bis(trimethylsilyl)methyl ligand to prepare the homoleptic uranium(III) alkyl derivative U[CH(SiMe 3 ) 2 ] 3 and cyclooctatetraenyl to produce steric saturation at the metal center and thus inhibit potential decomposition reactions. As an alternative to the ubiquitous cyclopentadienyl moiety, other workers have successfully employed sterically encumbered pyrazolylborate, bis(trimethylsilyl)amide, and bis(trimethylsilyl)benzamidinato ligands for the stabilization of actinide alkyl complexes.…”

Section: Introductionmentioning

confidence: 99%

Sterically Demanding Aryloxides as Supporting Ligands in Organoactinide Chemistry. Synthesis, Structural Characterization, and Reactivity of Th(O-2,6-t-Bu₂C₆H₃)₂(CH₂SiMe₃)₂ and Formation of the Trimeric Thorium Hydride Th₃H₆(O-2,6-t-Bu₂C₆H₃)₆

et al. 1996

View full text Add to dashboard Cite

Reaction of ThBr 4 (THF) 4 with 2 equiv of KOAr (Ar ) 2,6-t-Bu 2 C 6 H 3 ) produces the bis-(aryloxide) complex ThBr 2 (OAr) 2 (THF) 2 (1) in 67% yield. Alkylation of 1 with 2 equiv of Me 3 SiCH 2 MgCl allows the isolation of Th(OAr) 2 (CH 2 SiMe 3 ) 2 (2) in 61% yield. Thermolysis of 2 (benzene, 60 °C, 36 h) in the presence of NEt 3 results in the formation of the cyclometalated ligand redistribution product Th(OC 6 H 3 -t-BuCMe 2 CH 2 )(OAr) 2 (3). Reaction of 2 with 1 equiv of 2,6-dimethylphenyl isocyanate leads to insertion into the Th-C bond to yield (ArO) 2 Th[OC(dNR)CH 2 SiMe 3 ](CH 2 SiMe 3 ) (4; R ) 2,6-Me 2 C 6 H 3 ). Aminolysis of 2 with 2 equiv of 2,6-diisopropylaniline allows the isolation of the bis(amido) species Th(OAr) 2 (NH-2,6-i-Pr 2 C 6 H 3 ) 2 (5) in 92% yield. 2 reacts with dihydrogen (1.5 atm) over a period of 7 days to form the trimeric dihydride complex Th 3 (µ 3 -H) 2 (µ 2 -H) 4 (OAr) 6 (6). In the presence of 1 equiv of [HNMe 2 Ph][B(C 6 F 5 ) 4 ], 2 catalyzes the hydrogenation of 1-hexene (N t ) 1 h -1 ), while 6 is found to be a single-component catalyst for the analogous process (N t ) 3 h -1 ). Complexes 1-6 have been characterized by 1 H NMR and IR spectroscopy, microanalysis, and, in the case of 2 and 6, by single-crystal X-ray diffraction studies. 2 comprises a pseudotetrahedral thorium metal center bearing two aryloxide and two alkyl ligands. The O-Th-O angle between the aryloxide ligands (119.2(4)°) is significantly larger than the C-Th-C angle (101.4(6)°). Th-O and Th-C distances average 2.137(11) and 2.462(18) Å, respectively, while Th-C-Si angles are 125.9(8) and 122.8(8)°. The alkyl groups of 2 also display a reduced C-H coupling constant (J CH ) 98 Hz), suggestive of R-agostic interaction between the methylene group and the Th metal center. 6 exhibits a triangular arrangement of three thorium metal centers, each bearing two terminal aryloxide ligands. Two sides of the trimetallic core (Th-Th distances 3.781(1) and 3.818(1) Å) are bridged by single µ 2 -hydride ligands, while the third side is bridged by two µ 2 -hydride ligands (Th-Th distance 3.588(1) Å). Each face of the trimer is capped by a µ 3 -hydride ligand to produce a structurally unique M 3 (µ 3 -X) 2 (µ 2 -X) 4 X 6 geometry. Th-(µ 2 -H) and Th-(µ 3 -H) distances lie in the ranges 2.0(1)-2.3(1) and 2.3(1)-2.6(1) Å, respectively, while Th-O distances range from 2.126(7) to 2.164-(7) Å.

show abstract

Half-sandwich and mixed-ring uranium complexes

Cited by 20 publications

References 23 publications

Synthesis of Organouranium(IV) Triflates from U(OTf)4 or from Alkyl or Amide Precursors

Synthesis of Organouranium(IV) Triflates from U(OTf)4 or from Alkyl or Amide Precursors

Synthesis and crystal structure of pentavalent uranyl complexes. The remarkable stability of UO2X (X = I, SO3CF3) in non-aqueous solutions

Sterically Demanding Aryloxides as Supporting Ligands in Organoactinide Chemistry. Synthesis, Structural Characterization, and Reactivity of Th(O-2,6-t-Bu₂C₆H₃)₂(CH₂SiMe₃)₂ and Formation of the Trimeric Thorium Hydride Th₃H₆(O-2,6-t-Bu₂C₆H₃)₆

Contact Info

Product

Resources

About

Half-sandwich and mixed-ring uranium complexes

Cited by 20 publications

References 23 publications

Synthesis of Organouranium(IV) Triflates from U(OTf)4 or from Alkyl or Amide Precursors

Synthesis of Organouranium(IV) Triflates from U(OTf)4 or from Alkyl or Amide Precursors

Synthesis and crystal structure of pentavalent uranyl complexes. The remarkable stability of UO2X (X = I, SO3CF3) in non-aqueous solutions

Sterically Demanding Aryloxides as Supporting Ligands in Organoactinide Chemistry. Synthesis, Structural Characterization, and Reactivity of Th(O-2,6-t-Bu2C6H3)2(CH2SiMe3)2 and Formation of the Trimeric Thorium Hydride Th3H6(O-2,6-t-Bu2C6H3)6

Contact Info

Product

Resources

About

Sterically Demanding Aryloxides as Supporting Ligands in Organoactinide Chemistry. Synthesis, Structural Characterization, and Reactivity of Th(O-2,6-t-Bu₂C₆H₃)₂(CH₂SiMe₃)₂ and Formation of the Trimeric Thorium Hydride Th₃H₆(O-2,6-t-Bu₂C₆H₃)₆