Small molecule activation at uranium coordination complexes: control of reactivity via molecular architecture

Castro-Rodríguez, Ingrid; Meyer, Karsten

doi:10.1039/b513755c

Cited by 229 publications

(222 citation statements)

References 69 publications

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“…[29] The measured room-temperature magnetic moment (m eff = 3.44 m B at 300 K) is in the range of the values previously reported for mononuclear U IV complexes (2.5-3.55 m B ). [28,30] The observed low-temperature field dependency of the magnetization shows a small response of less than 0.9 m B , which is typical for U IV compounds ( Figure S6 in the Supporting Information). [31] These magnetic data provide clear evidence that complex 3 contains only U IV ions.…”

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confidence: 87%

A Nitrido‐Centered Uranium Azido Cluster Obtained from a Uranium Azide

2008

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Caught in the actinide: A tetranuclear azido/nitrido uranium anion containing eight end‐on bridging azido ligands and a μ4 interstitial nitrido ligand has been isolated and structurally characterized (see 1D chain; U green, Cs orange, I magenta, N blue, C white). A new two‐step procedure has been developed to promote the cluster assembly by oxidation of [UI3(thf)4] with a preformed uranium heptaazido complex.

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confidence: 87%

A Nitrido‐Centered Uranium Azido Cluster Obtained from a Uranium Azide

2008

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“…Forc omparison, we re-measured data for 1U, [9,15,21] and [U(N'') 3 (I)], [18] giving data consistent with literature values.I mportantly, 1U has asimilar low-temperature magnetization profile to 3U,while that of the non-Kramers [U(N'') 3 (I)] fails to saturate up to 7T . Further support for the uranium(III) oxidation state of 3U comes from low temperature (20 K) EPR spectroscopy at 9.5 GHz (Figure 2, right), where at ypical uranium(III) spectrum [22] is observed from ap owdered sample with effective g-values of g = 4.65, 1.33, and 0.89 arising from the ground Kramers doublet. Thenon-Kramers uranium(IV) ion would be expected to be EPR-silent under these conditions.…”

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confidence: 99%

Rare‐Earth‐ and Uranium‐Mesoionic Carbenes: A New Class of f‐Block Carbene Complex Derived from an N‐Heterocyclic Olefin

et al. 2017

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Neutral mesoionic carbenes (MICs) have emerged as an important class of carbene,however they are found in the free form or ligated to only afew d-block ions.Unprecedented f-block MIC complexes [M(N'') 3 {CN(Me)C(Me)N(Me)CH}] (M = U, Y, La, Nd;N '' = N(SiMe 3 ) 2 )a re reported. These complexes were prepared by af ormal 1,4-proton migration reaction when the metal triamides [M(N'') 3 ]w ere treated with the N-heterocyclic olefin H 2 C=C(NMeCH) 2 ,which constitutes an ew,g eneral wayt op repare MIC complexes.Q uantum chemical calculations on the 5f 3 uranium(III) complex suggest the presence of aU =Cd onor-acceptor bond, composed of aM IC!U s-component and aU (5f)!MIC(2p) p-backbond, but for the d 0 f 0 Ya nd La and 4f 3 Nd congeners only MIC!M s-bonding is found. Considering the generally negligible p-acidity of MICs,t his is surprising and highlights that greater consideration should possibly be given to recognizing MICs as potential p-acid ligands when coordinated to strongly reducing metals.Over the past three decades the field of stable singlet Nheterocyclic carbenes (NHCs, I,S cheme 1) has become ab urgeoning area.[1] Within that time,avariety of experimentally viable classes of carbenes related to I have emerged, including anionic-NHCs (II), [2] cyclic alkylaminocarbenes (CAAC, III), [3] and various charge-neutral mesoionic carbenes (MIC, IV-VI), [4] Scheme 1, where for the latter no reasonable canonical resonance forms can be drawn without assigning additional formal charges.Agrowing number of MICs of type IV are known, but it is notable that all examples to date pertain to either the free carbene,o rw ere formed at and remain coordinated to surprisingly few transition metal ions, [4] which contrasts to NHCs that have been coordinated to the majority of metals in the periodic table.[1] Where the bonding of these MICs to metals is concerned, complexes are usually considered to have strong MIC!metal s-donation. Given that strong s-donation, it is surprising that MIC complexes are limited to even only af ew transition metals, but this may reflect the limited range of methodologies to deliberately prepare metal-MIC complexes.Interestingly,any p-bonding components of metal-MIC bonds are,u nlike NHCs,r arely explicitly considered.[5] This is likely because MICs are anticipated to have at best weak p-acceptor character since the carbene is strongly stabilized by N-lone pair and vinyl groups,a se videnced by computational comparisons of different classes of carbenes. [6] We report herein the synthesis and characterization of rare-earth-MIC and uranium-MIC complexes,which are the first f-block-MIC complexes so by definition anew class of fblock-carbene complex. [7] Thec omplexes reported herein were prepared by the formal 1,4-proton migration of an Nheterocyclic olefin (NHO) that represents an ew,g eneral method by which to prepare MIC complexes.I nterestingly, quantum chemical calculations suggest that the 5f 3 uranium-(III) ion engages in aweak p-back-bond to the MIC utilizing a5felectron, whereas the ...

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“…The oxygen transfer to a metal center with the formation of the O=M(CO) moiety may be driven by the ancillary ligands, as recently shown in the case of the U III complex. 83,84,95, 96 In the η 1 -O complex (( Ad ArO) 3 tacnU III )=O=C•-O − , depending on the steric hindrance of the ligand around the U center, a further reaction can occur. By replacing the adamantane ligand (Ad) by the less bulky tert-butyl (t-Bu), an initial formation of a CO 2 adduct occurs.…”

Section: C-o Bond Cleavage and O Transfermentioning

confidence: 99%

Metal Coordination ofCO₂

Mascetti

2014

Encyclopedia of Inorganic and Bioinorganic Chemistry

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Even though carbon dioxide is used in a great number of industrial applications, it remains a molecule with low reactivity. Its activation by coordination to metal complexes is used in both stoichiometric and catalytic reactions. This article describes the different kinds of metal carbon dioxide complexes observed in the gas phase, in cryogenic solids, and in solution, and briefly presents the reactivity of coordinated CO 2 toward electrophiles and nucleophiles.

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Small molecule activation at uranium coordination complexes: control of reactivity via molecular architecture

Cited by 229 publications

References 69 publications

A Nitrido‐Centered Uranium Azido Cluster Obtained from a Uranium Azide

A Nitrido‐Centered Uranium Azido Cluster Obtained from a Uranium Azide

Rare‐Earth‐ and Uranium‐Mesoionic Carbenes: A New Class of f‐Block Carbene Complex Derived from an N‐Heterocyclic Olefin

Metal Coordination ofCO₂

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Small molecule activation at uranium coordination complexes: control of reactivity via molecular architecture

Cited by 229 publications

References 69 publications

A Nitrido‐Centered Uranium Azido Cluster Obtained from a Uranium Azide

A Nitrido‐Centered Uranium Azido Cluster Obtained from a Uranium Azide

Rare‐Earth‐ and Uranium‐Mesoionic Carbenes: A New Class of f‐Block Carbene Complex Derived from an N‐Heterocyclic Olefin

Metal Coordination ofCO2

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Metal Coordination ofCO₂