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ABSTRACT: Carbon monoxide (CO) is in principle an excellent resource from which to produce industrial hydrocarbon feedstocks as alternatives
to crude oil; however, CO has proven remarkably resistant to selective homologation, and the few complexes that can effect
this transformation cannot be recycled because liberation of the homologated product destroys the complexes or they are substitutionally
inert. Here, we show that under mild conditions a simple triamidoamine uranium(III) complex can reductively homologate CO
and be recycled for reuse. Following treatment with organosilyl halides, bis(organosiloxy)acetylenes, which readily convert
to furanones, are produced, and this was confirmed by the use of isotopically 13C-labeled CO. The precursor to the triamido uranium(III) complex is formed concomitantly. These findings establish that, under
appropriate conditions, uranium(III) can mediate a complete synthetic cycle for the homologation of CO to higher derivatives.
This work may prove useful in spurring wider efforts in CO homologation, and the simplicity of this system suggests that catalytic
CO functionalization may soon be within reach.
Proceedings of the National Academy of Sciences 06/2012; 109(24):9265-9270. · 9.68 Impact Factor
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ABSTRACT: Four new uranium-ruthenium complexes, [(Tren(TMS))URu(η(5)-C(5)H(5))(CO)(2)] (9), [(Tren(DMSB))URu(η(5)-C(5)H(5))(CO)(2)] (10), [(Ts(Tolyl))(THF)URu(η(5)-C(5)H(5))(CO)(2)] (11), and [(Ts(Xylyl))(THF)URu(η(5)-C(5)H(5))(CO)(2)] (12) [Tren(TMS)=N(CH(2)CH(2)NSiMe(3))(3); Tren(DMSB)=N(CH(2)CH(2)NSiMe(2)tBu)(3)]; Ts(Tolyl)=HC(SiMe(2)NC(6)H(4)-4-Me)(3); Ts(Xylyl)=HC(SiMe(2)NC(6)H(3)-3,5-Me(2))(3)], were prepared by a salt-elimination strategy. Structural, spectroscopic, and computational analyses of 9-12 shows: i) the formation of unsupported uranium-ruthenium bonds with no isocarbonyl linkages in the solid state; ii) ruthenium-carbonyl backbonding in the [Ru(η(5)-C(5)H(5))(CO)(2)](-) ions that is tempered by polarization of charge within the ruthenium fragments towards uranium; iii) closed-shell uranium-ruthenium interactions that can be classified as predominantly ionic with little covalent character. Comparison of the calculated U-Ru bond interaction energies (BIEs) of 9-12 with the BIE of [(η(5)-C(5)H(5))(3)URu(η(5)-C(5)H(5))(CO)(2)], for which an experimentally determined U-Ru bond disruption enthalpy (BDE) has been reported, suggests BDEs of approximately 150 kJ mol(-1) for 9-12.
Chemistry 09/2011; 17(40):11266-73. · 5.93 Impact Factor
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Angewandte Chemie International Edition 09/2011; 50(44):10440-3. · 13.45 Impact Factor
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ABSTRACT: Treatment of the complex [U(Tren(TMS))(Cl)(THF)] [1, Tren(TMS) = N(CH(2)CH(2)NSiMe(3))(3)] with Me(3)SiI at room temperature afforded known crystalline [U(Tren(TMS))(I)(THF)] (2), which is reported as a new polymorph. Sublimation of 2 at 160 °C and 10(-6) mmHg afforded the solvent-free dimer complex [{U(Tren(TMS))(μ-I)}(2)] (3), which crystallizes in two polymorphic forms. During routine preparations of 1, an additional complex identified as [U(Cl)(5)(THF)][Li(THF)(4)] (4) was isolated in very low yield due to the presence of a slight excess of [U(Cl)(4)(THF)(3)] in one batch. Reaction of 1 with one equivalent of lithium dicyclohexylamide or bis(trimethylsilyl)amide gave the corresponding amide complexes [U(Tren(TMS))(NR(2))] (5, R = cyclohexyl; 6, R = trimethylsilyl), which both afforded the cationic, separated ion pair complex [U(Tren(TMS))(THF)(2)][BPh(4)] (7) following treatment of the respective amides with Et(3)NH·BPh(4). The analogous reaction of 5 with Et(3)NH·BAr(f)(4) [Ar(f) = C(6)H(3)-3,5-(CF(3))(2)] afforded, following addition of 1 to give a crystallizable compound, the cationic, separated ion pair complex [{U(Tren(TMS))(THF)}(2)(μ-Cl)][BAr(f)(4)] (8). Reaction of 7 with K[Mn(CO)(5)] or 5 or 6 with [HMn(CO)(5)] in THF afforded [U(Tren(TMS))(THF)(μ-OC)Mn(CO)(4)] (9); when these reactions were repeated in the presence of 1,2-dimethoxyethane (DME), the separated ion pair [U(Tren(TMS))(DME)][Mn(CO)(5)] (10) was isolated instead. Reaction of 5 with [HMn(CO)(5)] in toluene afforded [{U(Tren(TMS))(μ-OC)(2)Mn(CO)(3)}(2)] (11). Similarly, reaction of the cyclometalated complex [U{N(CH(2)CH(2)NSiMe(2)Bu(t))(2)(CH(2)CH(2)NSiMeBu(t)CH(2))}] with [HMn(CO)(5)] gave [{U(Tren(DMSB))(μ-OC)(2)Mn(CO)(3)}(2)] [12, Tren(DMSB) = N(CH(2)CH(2)NSiMe(2)Bu(t))(3)]. Attempts to prepare the manganocene derivative [U(Tren(TMS))MnCp(2)] from 7 and K[MnCp(2)] were unsuccessful and resulted in formation of [{U(Tren(TMS))}(2)(μ-O)] (13) and [MnCp(2)]. Complexes 3-13 have been characterized by X-ray crystallography, (1)H NMR spectroscopy, FTIR spectroscopy, Evans method magnetic moment, and CHN microanalyses.
Inorganic Chemistry 08/2011; 50(19):9631-41. · 4.60 Impact Factor
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Chemistry 06/2011; 17(25):6909-12. · 5.93 Impact Factor
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ABSTRACT: Amine-elimination gave the two uranium-rhenium complexes [(Ts(Xy))(THF)(n)URe(η(5)-C(5)H(5))(2)] [Ts(Xy) = HC(SiMe(2)N-3,5-Me(2)C(6)H(3))(3); n = 0 or 1]; structural and theoretical analyses, and comparison to [(Tren(TMS))URe(η(5)-C(5)H(5))(2)] [Tren(TMS) = N(CH(2)CH(2)NSiMe(3))(3)], reveal an increasing σ-component to the U-Re bond upon removal of dative ancillary ligands from uranium with the π-component remaining essentially invariant.
Chemical Communications 01/2011; 47(1):295-7. · 6.17 Impact Factor
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ABSTRACT: Treatment of UCl(4) with one or two equivalents of IPr [IPr = {C(NArCH)(2)}, Ar = 2,6-diisopropylphenyl] gives [UCl(4)(IPr)(2)] as the sole isolable uranium-containing containing product; an X-ray diffraction study showed close Cl...C(carbene) contacts, but DFT analysis suggests the contacts are the result of aryl chloride steric repulsions as the Cl...C orbital interaction is negligible.
Dalton Transactions 09/2009; · 3.84 Impact Factor
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ABSTRACT: The unprecedented formation of a dinuclear tuck-in-tuck-over tuck-over dialkyl Tren-uranium(IV) complex and the first example of double dearylation of BPh(4)(-) in a molecular context to give a BPh(2)-functionalized uranium metallocycle are reported.
Journal of the American Chemical Society 08/2009; 131(30):10388-9. · 9.91 Impact Factor
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ABSTRACT: The first structurally authenticated molecular uranium-transition metal bond is reported; DFT studies show sigma- and pi-components in the U-Re bond and this is the first time that the latter component has been reported in an unsupported f-element-transition metal bond.
Chemical Communications 06/2009; · 6.17 Impact Factor
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ABSTRACT: The synthesis and characterization of the first unsupported Ga-Y bond in [Y{Ga(NArCH)(2)}{C(PPh(2)NSiMe(3))(2)}(THF)(2)] (Ar = 2,6-diisopropylphenyl) is described; structural and computational analyses are consistent with a highly polarized covalent Ga-Y bond.
Inorganic Chemistry 04/2009; 48(8):3520-2. · 4.60 Impact Factor
