Homolysis of the Ln–N bond: Synthesis, characterization and catalytic activity of organolanthanide(II) complexes with 2-pyridylmethyl and 3-pyridylmethyl-functionalized indenyl ligands

Wang, Shaowu; Yan, Feng; Mao, Lili; Sheng, Enhong; Yang, Gaosheng; Xie, Meihua; Wang, Shaoyin; Wei, Yun; Huang, Zirui

doi:10.1016/j.jorganchem.2005.12.002

Cited by 15 publications

(16 citation statements)

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“…À couple [25] allowing, for example, redox-inactive complexes such as [YCp* 3 ] to reduce dinitrogen to form, for example [{Cp* 2 Y} 2 (m-N 2 )]. SIR mechanisms have been observed in other organometallic f-block systems [26][27][28] . To confirm that Y À N bond homolysis is occurring in our case, [29] the reaction between 1 and [Y{N(SiMe 3 ) 2 } 3 ] in the presence of dihydroanthracene (DHA) shows not only the rapid formation of 3 plus three equivalents of HN(SiMe 3 ) 2 by 1 H NMR spectroscopy, but also a stoichiometric quantity of anthracene (0.5 equiv), formed by H-atom abstraction from DHA by the silylaminyl radical CN(SiMe 3 ) 2 , the SIR byproduct.…”

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confidence: 78%

Single‐Electron Uranyl Reduction by a Rare‐Earth Cation

et al. 2010

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Unlike their transition-metal analogues, the oxo groups of the uranyl dication, [UO 2 ] 2+ , which has a linear geometry and short, strong UÀO bonds are commonly considered inert. [1] Very little Lewis base character has been demonstrated for the uranyl oxo groups, [2,3] which makes them poor models for the heavier, highly radioactive transuranic actinyl cations such as neptunyl [NpO 2 ] n+ (n = 1, 2). [4,5] The heavier actinyls are important components in nuclear waste and demonstrate oxo basicity that can give rise to poorly understood cluster formation and problems in nuclear waste PUREX separation processes.[6] However, it has been shown recently that the more Lewis basic, pentavalent uranyl cation, [UO 2 ] + , can be stabilized indefinitely using suitable equatorial-binding ligands and anaerobic conditions. [7,8] Usually the [UO 2 ] + cation decomposes by disproportionation, which is also a poorly understood process, but is important in the precipitation of uranium salts out of aqueous environments. [9,10] The disproportionation is suggested, by analogy with the transuranic metal oxo Lewis base behavior, to involve the formation of cation-cation interactions (CCIs) [11,12] in which the oxo groups ligate to adjacent actinyl centers forming diamond (A) or T-shaped (B) dimers or clusters which can then allow the transfer of protons and electrons between metals, such as in C. [13] We reported that the use of rigid, Pacman-shaped macrocycles can allow the isolation of heterobimetallic uranyltransition metal complexes that form an oxo interaction with the transition metal in the solid state and solution, [14] and how the inclusion of more than one metal cation alongside the uranyl cation led to isolable, stable pentavalent uranyl complexes with a covalently functionalized oxo group. [15] More recently, pentavalent uranyl complexes with Group 1 cation oxo-coordination, [16] and a doubly silylated complex [17] have been isolated. Here, we report the first uranyl-4f metal interaction, prepared by either standard, or sterically induced reduction procedures, and demonstrate strong magnetic coupling between the 4f and 5f electrons.The reaction between the divalent samarium silylamide [Sm(THF) 2 {N(SiMe 3 ) 2 } 2 ] and the uranyl Pacman complex [UO 2 (py)(H 2 L)] (1) in pyridine resulted in the deposition of the new uranyl-samarium complex [UO 2 Sm(py) 2 (L)] 2 (2) as a very poorly soluble, thermally stable, red crystalline powder in good yield (Scheme 1), and containing crystals suitable for single-crystal X-ray diffraction studies (Figure 1).The 1 H NMR spectrum of 2 in [D 5 ]pyridine reveals the presence of paramagnetically shifted resonances between d = 12.4 and À21.5 ppm, the number and integrals of which are consistent with the retention of a wedged, Pacman structure in solution of C s symmetry. In the solid state, the molecular structure shows that 2 is dimeric (Figure 1) and the unit cell contains two similar molecules. Focusing on one molecule of 2, both the uranium and samarium centers are sevencoordinate w...

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confidence: 78%

Single‐Electron Uranyl Reduction by a Rare‐Earth Cation

et al. 2010

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“…Crowded f-block organometallic complexes such as [LnCp* 3 ] (Cp* = C 5 Me 5 ) can provide a reducing electron through the [Cp*]/[Cp*] À couple [25] allowing, for example, redox-inactive complexes such as [YCp* 3 ] to reduce dinitrogen to form, for example [{Cp* 2 Y} 2 (m-N 2 )]. SIR mechanisms have been observed in other organometallic f-block systems [26][27][28] . To confirm that Y À N bond homolysis is occurring in our case, [29] the reaction between 1 and [Y{N(SiMe 3 ) 2 } 3 ] in the presence of dihydroanthracene (DHA) shows not only the rapid formation of 3 plus three equivalents of HN(SiMe 3 ) 2 by 1 H NMR spectroscopy, but also a stoichiometric quantity of anthracene (0.5 equiv), formed by H-atom abstraction from DHA by the silylaminyl radical CN(SiMe 3 ) 2 , the SIR byproduct.…”

mentioning

confidence: 78%

Single‐Electron Uranyl Reduction by a Rare‐Earth Cation

et al. 2010

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Unlike their transition-metal analogues, the oxo groups of the uranyl dication, [UO 2 ] 2+ , which has a linear geometry and short, strong UÀO bonds are commonly considered inert. [1] Very little Lewis base character has been demonstrated for the uranyl oxo groups, [2,3] which makes them poor models for the heavier, highly radioactive transuranic actinyl cations such as neptunyl [NpO 2 ] n+ (n = 1, 2). [4,5] The heavier actinyls are important components in nuclear waste and demonstrate oxo basicity that can give rise to poorly understood cluster formation and problems in nuclear waste PUREX separation processes. [6] However, it has been shown recently that the more Lewis basic, pentavalent uranyl cation, [UO 2 ] + , can be stabilized indefinitely using suitable equatorial-binding ligands and anaerobic conditions. [7,8] Usually the [UO 2 ] + cation decomposes by disproportionation, which is also a poorly understood process, but is important in the precipitation of uranium salts out of aqueous environments. [9,10] The disproportionation is suggested, by analogy with the transuranic metal oxo Lewis base behavior, to involve the formation of cation-cation interactions (CCIs) [11,12] in which the oxo groups ligate to adjacent actinyl centers forming diamond (A) or T-shaped (B) dimers or clusters which can then allow the transfer of protons and electrons between metals, such as in C. [13] We reported that the use of rigid, Pacman-shaped macrocycles can allow the isolation of heterobimetallic uranyltransition metal complexes that form an oxo interaction with the transition metal in the solid state and solution, [14] and how the inclusion of more than one metal cation alongside the uranyl cation led to isolable, stable pentavalent uranyl complexes with a covalently functionalized oxo group. [15] More recently, pentavalent uranyl complexes with Group 1 cation oxo-coordination, [16] and a doubly silylated complex [17] have been isolated. Here, we report the first uranyl-4f metal interaction, prepared by either standard, or sterically induced reduction procedures, and demonstrate strong magnetic coupling between the 4f and 5f electrons.The reaction between the divalent samarium silylamide [Sm(THF) 2 {N(SiMe 3 ) 2 } 2 ] and the uranyl Pacman complex [UO 2 (py)(H 2 L)] (1) in pyridine resulted in the deposition of the new uranyl-samarium complex [UO 2 Sm(py) 2 (L)] 2 (2) as a very poorly soluble, thermally stable, red crystalline powder in good yield (Scheme 1), and containing crystals suitable for single-crystal X-ray diffraction studies (Figure 1). [*] Prof.

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“…The majority of the MMA polymers produced by using Eu 2+ -containing functionalized indenyl complexes 64 , 65 , 72 , and 73 as initiators is syndiotactic. [11,77] However, when complexes 66 – 68 were used in dimethoxyethane or THF, a 1:1:1 ratio of isotactic, syndiotactic, and atactic polymers was obtained. However, predominantly syndiotactic polymers were obtained when using 66 in toluene, and a decrease in the ratio of syndiotactic to isotactic polymers was observed with 70 when the solvent was changed from THF or dimethoxyethane to toluene, which suggests that a solvent effect influences the stereochemistry of these polymers.…”

Section: Applications Of Eu2+-containing Complexesmentioning

confidence: 99%

“…The presence of several tacticities in the synthesized polymers was attributed to the rac / meso interconversion, which is favored by solvents including THF and dimethoxyethane. [77] While the stereochemistry of the polymers showed dependency on the solvent used, it is still unclear whether this stereoregularity is influenced by the nature of the initiator, specifically by the metal or ligands. A similar study that uses different initiators (for example, different divalent lanthanide metal ions or a ligand system other than indene compounds) could answer this question.…”

Section: Applications Of Eu2+-containing Complexesmentioning

confidence: 99%

“…Eu 2+ ‐containing complexes 64 – 73 , which contain functionalized indenyl ligands are used in the polymerization of MMA (Figure 8). 11,75–77 The activity of these complexes in polymerizations and the stereochemistries of the resulting polymers are dependent on temperature and solvent (Figure 7). High activity is observed at low temperatures (–30 to –60 °C for complexes 64 and 65 ; 0 to –60 °C for complexes 66 – 69 , 72 , and 73 ; –30 to –45 °C for complexes 70 and 71 ), and these complexes have solvent‐dependent activities.…”

Section: Applications Of Eu2+‐containing Complexesmentioning

confidence: 99%

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Developments in the Coordination Chemistry of Europium(II)

Garcia

Allen

2012

Eur J Inorg Chem

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Recent advances in the coordination chemistry of Eu2+ are reviewed. Common synthetic routes for generating discrete Eu2+-containing complexes reported since 2000 are summarized, followed by a description of the reactivity of these complexes and their applications in reduction chemistry, polymerization, luminescence, and as contrast agents for magnetic resonance imaging. Rapid development of the coordination chemistry of Eu2+ has led to an upsurge in the utilization of Eu2+-containing complexes in synthetic chemistry, materials science, and medicine.

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Homolysis of the Ln–N bond: Synthesis, characterization and catalytic activity of organolanthanide(II) complexes with 2-pyridylmethyl and 3-pyridylmethyl-functionalized indenyl ligands

Cited by 15 publications

References 65 publications

Single‐Electron Uranyl Reduction by a Rare‐Earth Cation

Single‐Electron Uranyl Reduction by a Rare‐Earth Cation

Single‐Electron Uranyl Reduction by a Rare‐Earth Cation

Developments in the Coordination Chemistry of Europium(II)

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