Divergent reactivity of [(κ3-L)ThCl2(dme)] with Grignard reagents: Alkylation, ancillary ligand transfer to magnesium, and halide exchange caught in the act

Cruz, Carlos; Chu, Terry; Emslie, David J. H.; Jenkins, Hilary A.; Harrington, Laura E.; Britten, James F.

doi:10.1016/j.jorganchem.2010.08.048

Cited by 17 publications

(8 citation statements)

References 60 publications

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“…5), unlike the uranium(IV) XA 2 precursor, 3, is free from occluded alkali metal salt. A molecule of DME is also κ 2 -coordinated to uranium with U-O bond lengths of 2.580(6) and 2.655(7) Å, and as is typical in 5f-element complexes of the XA 2 ligand, [3][4][5]39 the ligand backbone in complex 5 is planar. All uranium-XA 2 ligand bond lengths in 5 are 0.04-0.06 Å longer than those in complex 3, consistent with the increased ionic radius of uranium(III) relative to uranium(IV) [for a coordination number of six: U 4+ = 0.89 Å and U 3+ = 1.03 Å].…”

Section: Reduction To Uranium(iii)mentioning

confidence: 90%

“…General synthetic procedures have been reported elsewhere. [3][4][5][6]39 Deuterated solvents were purchased from ACP chemicals, UO 3 was purchased from Strem Chemicals, and K[B(C 6 F 5 ) 4 ] was purchased from Boulder Scientific. Thioxanthone, tetraglyme, Pd(OAc) 2 , NaOtBu, DPEPhos, KH (30 wt% in mineral oil), K, naphthalene and [NBu 4 ]Br were purchased from Sigma-Aldrich.…”

Section: General Detailsmentioning

confidence: 99%

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Rigid NON- and NSN-ligand complexes of tetravalent and trivalent uranium: comparison of U–OAr2 and U–SAr2 bonding

et al. 2012

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A rigid NSN-donor proligand, 4,5-bis(2,6-diisopropylanilino)-2,7-di-tert-butyl-9,9-dimethylthioxanthene (H(2)[TXA(2)], 1) was prepared by palladium-catalyzed coupling of 2,6-diisopropylaniline with 4,5-dibromo-2,7-di-tert-butyl-9,9-dimethylthioxanthene. Deprotonation of 1 using (n)BuLi provided Li(2)(DME)(2)[TXA(2)] (2), and subsequent reaction with UCl(4) afforded [Li(DME)(3)][(TXA(2))UCl(3)] (4). The analogous NON-donor ligated complex [(XA(2))UCl(3)K(DME)(3)] [3; XA(2) = 4,5-bis(2,6-diisopropylanilino)-2,7-di-tert-butyl-9,9-dimethylxanthene] was prepared by the reaction of K(2)(DME)(x)[XA(2)] with UCl(4). A cyclic voltammogram (CV) of 3 in THF/[NBu(4)][B(C(6)F(5))(4)] at 200 mV s(-1) showed an irreversible reduction to uranium(III) at E(pc) = -2.46 V versus FeCp(2)(0/+1), followed by a product wave at E(1/2) = -1.83 V. Complex 4 also underwent irreversible reduction to uranium(iii) [E(pc) = -2.56 V], resulting in an irreversible product peak at E(pa) = -1.83 V. One-electron reduction of complexes 3 and 4 using K(naphthalenide) under an argon atmosphere in DME yielded 6-coordinate [(XA(2))UCl(DME)] (5) and the thermally unstable 7-coordinate [(TXA(2))U(DME)Cl(2)Li(DME)(2)] (6), respectively. The U-S distances in 4 and 6 are uncommonly short, the C-S-U angles are unusually acute, and the thioxanthene backbone of the TXA(2) ligand is significantly bent. By contrast, the xanthene backbone in XA(2) complexes 3 and 5 is planar. However, κ(3)-coordination and an approximately meridional arrangement of the ancillary ligand donor atoms is maintained in all complexes. DFT and Atoms in Molecules (AIM) calculations were carried out on 3, 4, 5, 6, [(XA(2))UCl(3)](-) (3B), [(TXA(2))UCl(2)(DME)](-) (6B) and [(TXA(2))UCl(DME)] (6C) to probe the extent of covalency in U-SAr(2) bonding relative to U-OAr(2) bonding.

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Section: Reduction To Uranium(iii)mentioning

confidence: 90%

Section: General Detailsmentioning

confidence: 99%

Rigid NON- and NSN-ligand complexes of tetravalent and trivalent uranium: comparison of U–OAr2 and U–SAr2 bonding

et al. 2012

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“…General synthetic procedures have been reported elsewhere. ,,,, Deuterated solvents were purchased from ACP Chemicals. Neopentyl chloride was purchased from Strem Chemicals.…”

Section: Experimental Sectionmentioning

confidence: 99%

Uranium(IV) Alkyl Complexes of a Rigid Dianionic NON-Donor Ligand: Synthesis and Quantitative Alkyl Exchange Reactions with Alkyllithium Reagents

et al. 2013

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Reaction of [(XA2)UCl3{K(dme)3}] (XA2 = 4,5-bis(2,6-diisopropylanilino)-2,7-di-tert-butyl-9,9-dimethylxanthene) with 2 equiv of ((trimethylsilyl)methyl)lithium or neopentyllithium afforded red-orange [(XA2)U(CH2SiMe3)2] (1) and dark red [(XA2)U(CH2CMe3)2] (2), respectively. Reaction of 1 with an additional 1 equiv of LiCH2SiMe3 in THF yielded yellow [Li(THF) x ][(XA2)U(CH2SiMe3)3] (3), and reaction of [(XA2)UCl3{K(dme)3}] with 3 equiv of methyllithium in dme afforded yellow [Li(dme)3][(XA2)UMe3] (4). Reaction of 1 with 2.1 equiv of LiCH2CMe3 in benzene resulted in rapid conversion to 2, with release of 2 equiv of LiCH2SiMe3. Similarly, reaction of 1 with 3.3 equiv of MeLi in THF provided 4 as the [Li(THF) x ]+ salt, accompanied by 2 equiv of LiCH2SiMe3. These unusual alkyl exchange reactions resemble salt metathesis reactions, but with elimination of an alkyllithium instead of a lithium halide. Addition of a large excess of LiCH2SiMe3 to 2 or 4 did not generate detectable amounts of 1 by NMR spectroscopy, suggesting that the equilibrium in these reactions lies far to the side of complexes 2 and 4. In contrast, the reaction of [(XA2)Th(CH2SiMe3)2] (1-Th) with 2.2 equiv of LiCH2CMe3 yielded an approximate 1:1:3:1 mixture of [(XA2)Th(CH2CMe3)2] (2-Th), [(XA2)Th(CH2SiMe3)(CH2CMe3)] (5-Th), LiCH2SiMe3, and LiCH2CMe3.

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“…However, it should be noted that in combination with metals which are too small to fit well within the ligand binding pocket (e.g. Mg 8 or Li; vide infra), significant flexing of the ligand backbone may be observed.…”

Section: Introductionmentioning

confidence: 99%

Cyclometalation and coupling of a rigid 4,5-bis(imino)acridanide pincer ligand on yttrium

Wong

Emslie

2015

Dalton Trans.

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An extremely rigid NNN-donor proligand, 4,5-bis{(diphenylmethylene)amino}-2,7,9,9-tetramethylacridan, H[AIm2] was prepared in five steps starting from 5-methyl-2-aminobenzoic acid and 4-bromotoluene. Reaction of intensely orange H[AIm2] with LiCH2SiMe3 formed deep blue Li(x)[AIm2]x (x = 2 in the solid state), while reaction with [Y(CH2SiMe3)3(THF)2] (0.5 equiv.) afforded deep blue [Y(AIm2)(AIm)] (1; AIm = an AIm2 ligand cyclometalated at the ortho-position of one of the phenyl rings). Compound 1 slowly isomerizes to form green-brown 2, which contains a single trianionic, hexadentate ligand that features one amine, two imine, and three amido donors. The acridanide backbone and one imine group in each of the original AIm2 ligands is intact, but the two acridanide backbones are now linked by an isoindoline heterocycle. Yttrium in 2 is coordinated to six nitrogen donors and the ortho carbon of an isoindoline phenyl substituent. The intense colours of H[AIm2], Li(x)[AIm2]x and 1 were shown by TD-DFT calculations to arise from charge transfer transitions from the HOMO, which is localized on the acridanide ligand backbone, to the LUMO and LUMO+1, which are localized on the imine substituents. The conversion of 1 to 2 was studied by UV-Visible absorption spectroscopy and is first-order with a half-life of 7.8 hours at room temperature.

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Divergent reactivity of [(κ3-L)ThCl2(dme)] with Grignard reagents: Alkylation, ancillary ligand transfer to magnesium, and halide exchange caught in the act

Cited by 17 publications

References 60 publications

Rigid NON- and NSN-ligand complexes of tetravalent and trivalent uranium: comparison of U–OAr2 and U–SAr2 bonding

Rigid NON- and NSN-ligand complexes of tetravalent and trivalent uranium: comparison of U–OAr2 and U–SAr2 bonding

Uranium(IV) Alkyl Complexes of a Rigid Dianionic NON-Donor Ligand: Synthesis and Quantitative Alkyl Exchange Reactions with Alkyllithium Reagents

Cyclometalation and coupling of a rigid 4,5-bis(imino)acridanide pincer ligand on yttrium

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