Structure and reactions of a metallacyclic complex containing a remarkably long uranium–carbon bond

Boaretto, Rita; Roussel, Paul; Kingsley, Andrew J.; Munslow, Ian J.; Sanders, Christopher J.; Alcock, Nathaniel W.; Scott, Peter

doi:10.1039/a903783g

Cited by 54 publications

(57 citation statements)

References 23 publications

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“…[24] The UÀC distance in 2 is significantly longer than that in the only other tetravalent uranium NHC adduct, [U-(C 5 Me 5 ) 2 (=O)(C{NMeCMe} 2 )], which has a U À C distance of 2.639 (9) . [9] All the U À C bonds in 2 are longer (within e.s.d.s) than those in the trivalent complex [U{N(SiMe 3 ) 2 } 3 -{C(NMeCMe) 2 }] (2.672 (5) [25] There is no evidence of any interaction with lattice solvent or adjacent molecules in the structure.…”

Section: Resultsmentioning

confidence: 94%

Synthesis and Small Molecule Reactivity of Uranium(IV) Alkoxide Complexes with both Bound and Pendant N‐heterocyclic Carbene Ligands

Arnold

Blake

Wilson

2005

Chemistry A European J

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The syntheses of two tetravalent uranium alkoxide-carbene complexes are reported, [UIL3], and [UL4] where L = OCMe2CH2[1-C(NCHCHNiPr)]. The latter shows dynamic behaviour of the alkoxycarbene ligands in solution at room temperature, and the crystal structure of [UL4] shows that one carbene group remains uncoordinated. The unbound N-heterocyclic carbene group is trapped by a range of reagents such as 16-valence-electron metal carbonyl fragments and BH3 moieties, forming, for example, [UL3(mu-L)W(CO)5], [UL2(mu-L)2Mo(CO)4], and [UL(n)(L-BH3)(4-n)] (n = 1-4), demonstrating the potential for these hemilabile electropositive metal-carbene complexes to participate in the bifunctional activation of small molecules.

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Section: Resultsmentioning

confidence: 94%

Synthesis and Small Molecule Reactivity of Uranium(IV) Alkoxide Complexes with both Bound and Pendant N‐heterocyclic Carbene Ligands

Arnold

Blake

Wilson

2005

Chemistry A European J

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“…Tren-uranium tetraphenylborate complexes were targeted via alkyl precursors, namely [U{N(CH 2 CH 2 NSiMe 2 Bu t ) 2 (CH 2 CH 2 NSi-MeBu t CH 2 )}] 23 (21) (24), after addition of donor solvents respectively, as a pale green solids in near-quantitative yield (Scheme 7).…”

Section: Borate Derivativesmentioning

confidence: 99%

“…5, 23,29 was initially prepared by treatment of 2 with a range of lithium, potassium, magnesium and zinc alkyls in pentane to give brown solutions from which extremely air-sensitive orange-brown crystals of 21 could be isolated. 5, 23,29 was initially prepared by treatment of 2 with a range of lithium, potassium, magnesium and zinc alkyls in pentane to give brown solutions from which extremely air-sensitive orange-brown crystals of 21 could be isolated.…”

Section: Tren-uranium -Group 14 Complexesmentioning

confidence: 99%

“…Complex 21 reacts with stoichiometric quantities of the acetylenes HCCX (X = H, Ph, p-tolyl) to afford the respective mononuclear acetylide complexes [U(Tren DMBS )(C 2 X)] [X = H (27), Ph (28), p-tolyl (29)], although structural characterisation is lacking for 27. Complex 21 reacts with stoichiometric quantities of the acetylenes HCCX (X = H, Ph, p-tolyl) to afford the respective mononuclear acetylide complexes [U(Tren DMBS )(C 2 X)] [X = H (27), Ph (28), p-tolyl (29)], although structural characterisation is lacking for 27.…”

Section: Tren-uranium -Group 14 Complexesmentioning

confidence: 99%

“…29 Subsequently, cyclometallation chemistry at uranium has been explored using the less sterically demanding Tren TMS ligand system. It was reported that under these conditions over a period of a few hours deuteration of all SiMe 2 groups as well as the metallacyclic CH 2 unit was observed.…”

Section: Tren-uranium -Group 14 Complexesmentioning

confidence: 99%

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Uranium triamidoamine chemistry

Gardner

Liddle

2015

Chem. Commun.

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Triamidoamine (Tren) complexes of the p- and d-block elements have been well-studied, and they display a diverse array of chemistry of academic, industrial and biological significance. Such in-depth investigations are not as widespread for Tren complexes of uranium, despite the general drive to better understand the chemical behaviour of uranium by virtue of its fundamental position within the nuclear sector. However, the chemistry of Tren-uranium complexes is characterised by the ability to stabilise otherwise reactive, multiply bonded main group donor atom ligands, construct uranium-metal bonds, promote small molecule activation, and support single molecule magnetism, all of which exploit the steric, electronic, thermodynamic and kinetic features of the Tren ligand system. This Feature Article presents a current account of the chemistry of Tren-uranium complexes.

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Characterizing Pressure‐Induced Uranium CH Agostic Bonds

et al. 2015

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The diuranium(III) compound [UN'' 2 ] 2 (m-h 6 :h 6 -C 6 H 6 )( N '' = N(SiMe 3 ) 2 )h as been studied using variable, high-pressure single-crystal X-ray crystallography,and density functional theory .Inthis compound, the low-coordinate metal cations are coupled through p-and d-symmetric arene overlap and show close metalÀCH contacts with the flexible methyl CH groups of the sterically encumbered amido ligands.The metalmetal separation decreases with increasing pressure,b ut the most significant structural changes are to the close contacts between ligand CH bonds and the Ucenters.A lthough the interatomic distances are suggestive of agostic-type interactions between the Ua nd ligand peripheral CH groups,Q TAIM (quantum theory of atoms-in-molecules) computational analysis suggests that there is no such interaction at ambient pressure.H owever,Q TAIM and NBO analyses indicate that the interaction becomes agostic at 3.2 GPa.Simple,low-coordinate U III complexes have been recently reported to show arich reactivity with inert small molecules. [1] This reactivity is despite the fact that in the solid state, structural studies show close contacts between the metal and peripheral ligand Cand Hatoms that sometimes protect ap otential coordination site and sometimes simply block further reactions.F or example,h ydrocarbon solutions of [U(N'') 3 ](N'' = N(SiMe 3 ) 2 ) [2] (containing three UÀC SiMe3 close contacts,a verage distance = 3.047 ) reductively couple CO, [3] whereas those of [U{N(SiMe 2 Ph) 2 } 3 ]( containing three U À C ipsoPh close contacts,average distance = 3.093 ) [4] do not.Arguably the most useful homogeneous CÀHb ond functionalization reactions currently being developed for dblock metal catalysts rely on CH metallation of ab ound substrate. [5] Similarly,U complexes that show CH metallation [6] have been developed into catalysts for N-heterocycle coupling,f or example. [7] TheU III aryloxide [{(ArO) 3 tacn}U-(cC 6 H 12 )] (tacn = 1,4,7-triazacyclonane) shows an intermolecular CÀHc ontact to am olecule of cyclohexane solvent with aU À Cd istance of 3.864 (7) a nd an h 2 -CH interaction suggested by calculations. [8] More generally,a gostic interactions between uranium centers and ligand CH groups are often invoked from inspection of close metal-ligand contacts in X-ray structures. [9] No routine method exists for assessing the strength and influence of weak interactions to confirm ag enuine agostic interaction in paramagnets,w here traditional NMR spectral methods do not work [10] and neutron diffraction studies are not readily available. [11] Computationally,t he electron-density-basedq uantum theory of atoms-inmolecules (QTAIM), with its simple definition of achemical bond, has been successfully employed to identify agostic interactions. [12] Systems in which energetically competitive structures are related by subtle changes,such as agostic interactions,may be sensitive to external conditions such as pressure.H igh pressure has previously shown unconventional behavior in coordination compounds...

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Structure and reactions of a metallacyclic complex containing a remarkably long uranium–carbon bond

Cited by 54 publications

References 23 publications

Synthesis and Small Molecule Reactivity of Uranium(IV) Alkoxide Complexes with both Bound and Pendant N‐heterocyclic Carbene Ligands

Synthesis and Small Molecule Reactivity of Uranium(IV) Alkoxide Complexes with both Bound and Pendant N‐heterocyclic Carbene Ligands

Uranium triamidoamine chemistry

Characterizing Pressure‐Induced Uranium CH Agostic Bonds

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