π-cyclopentadienyl compounds of uranium-IV and thorium-IV

Reynolds, Larry T.; Wilkinson, Geoffrey

doi:10.1016/0022-1902(56)80051-1

Cited by 175 publications

(108 citation statements)

References 8 publications

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“…The U-X and average U-C distances are larger in the U(III) compound than in the U(IV) precursor, by 0.084-0.145 and 0.025-0.044 Å respectively, correlating with the increase of 0.160 Å in the radii of the U 3+ and U 4+ ions. 27 The lengthening of the U-S and average U-C distances from Cp 3 29 We also note the very slight variation of the Cp C-C bond lengths when passing from the U(IV) to the U(III) species, which is indicative that the reduction process does not affect the Cp ring.…”

Section: Molecular Geometry Optimizationsmentioning

confidence: 82%

“…For instance, the MPA metal spin density is equal to 2.90 instead of 3 for the [Cp 3 UCl] -anion, while it is 2.18 instead of 2 for the neutral U(IV) complex. In each case a small delocalization of electron spin on the ligands occurs.…”

Section: View Article Onlinementioning

confidence: 99%

“…The cyclopentadienyl ligand has occupied a predominant place in this discipline from its beginning with the synthesis of the triscyclopentadienyl compounds Cp 3 UCl 3 and Cp 3 U 4 (Cp = C 5 H 5 ), the first organo-uranium(IV)a n d( III) complexes, isolated in 1956 and 1970, respectively. Some years later, the bispentamethylcyclopentadienyl compound Cp* 2 UCl 2 (Cp* = C 5 Me 5 ) was found to be, as well as Cp 3 UCl, the precursor of an important family of derivatives. 5 The recent period is marked by the speeding up of emergence of new classes of organo-uranium compounds.…”

Section: Introductionmentioning

confidence: 99%

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A DFT and experimental investigation of the electron affinity of the triscyclopentadienyl uranium complexes Cp3UX

et al. 2009

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Relativistic Density Functional Theory (DFT) based methods coupled with the Conductor-like Screening Model (COSMO) for a realistic solvation approach are used to investigate the electron affinity (EA) of a series of triscyclopentadienyl uranium complexes Cp 3 UX (X = Cl, BH 4 ,SPh,S i Pr and O i Pr) related to the U(IV)/U(III) redox system. E 1/2 half-wave potentials have been measured in solution (THF) under the same rigorous conditions for all the species under consideration. A good correlation (r 2 = 0.99) is found between the computed EA values, either in the gas phase or in solution, and the experimental half-wave potentials; the study brings to light the importance of spin-orbit coupling effects which must be taken into account in order to achieve the observed agreement between theory and experiment. The influence of the electron donating character of the X ligand on the orbital involved in the reduction process, namely the lowest unoccupied molecular orbital (LUMO) of the neutral U(IV) complexes, and on the EAs is discussed.

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Section: Molecular Geometry Optimizationsmentioning

confidence: 82%

Section: View Article Onlinementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A DFT and experimental investigation of the electron affinity of the triscyclopentadienyl uranium complexes Cp3UX

et al. 2009

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“…1,2 The synthesis, structure, and bonding of bis(cyclooctatetraenyl)uranium (uranocene) was first reported in a seminal paper by Streitwieser and MullerWesterhoff in 1968. 3 The focuses of the present work are the distinctive linear hexavalent actinyl ions [OAnO] 2+ (An = U, Np, Pu), which exist in solutions and as solids.…”

Section: ■ Introductionmentioning

confidence: 99%

Synthesis and Hydrolysis of Uranyl, Neptunyl, and Plutonyl Gas-Phase Complexes Exhibiting Discrete Actinide–Carbon Bonds

et al. 2016

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Gas-phase organoactinyl complexes possessing discrete An−C bonds (An = U, Np, Pu) were synthesized in a quadrupole ion trap by endothermic decarboxylation of [AnO 2 (O 2 C−R) 3 ]− anion complexes in which a formally AnO 2 2+ actinyl core is coordinated by three carboxylate ligands, with R = CH 3 (methyl), CH 3 CC (1-propynyl), C 6 H 5 (phenyl), C 6 F 5 (pentafluorophenyl). Decarboxylation and competing ligand loss were studied computationally by density functional theory complementing experiment. Although decarboxylation was computed to be the energetically most favorable process in all cases, reduction from An(VI) to An(V) via neutral ligand loss was often prevalent, particularly for An = Np, Pu, presumably resulting from barriers associated with decarboxylation. Comparative hydrolysis rates of the An−C bonds were experimentally determined, and the chemical properties of these bonds were analyzed by the quantum theory of atoms in molecules. The measured hydrolysis rates differed by up to 3 orders of magnitude: the fastest was for [(CH 3 CC)UO 2 (O 2 C− CCCH 3 ) 2 ]− and the slowest for [(C 6 F 5 )PuO 2 (O 2 C−C 6 F 5 ) 2 ]− . There is a general correlation between hydrolysis exothermicity and hydrolysis rate. Prototypical hydrolysis reaction pathways computed for R = CH 3 (An = U, Np) reveal a mechanism in which an outer-sphere water becomes inner-sphere concomitant with transfer of an H atom to yield an OH ligand and CH 4 , with a net energy release of 170 kJ mol −1 and a transition state barrier of 45 kJ mol −1 for An = U. Infrared multiphoton dissociation spectra of selected complexes were acquired to confirm the predicted structures by agreement between the computed and observed vibrational frequencies. The experiment and theory results provide an evaluation of the comparative propensities for formation of the organoactinyls as a function of actinide and carboxylate and an assessment of the nature and stability toward hydrolysis of the primarily ionic An−C bonds.

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“…Nonetheless, with the notable exception of cyclopentadienyl derivatives, progress has generally been hampered by a lack of synthetic methods or suitable ligand transfer reagents. The first uranium-p-ligand complex employed cyclopentadienyl in the complex [U(Z 5 -C 5 H 5 ) 3 Cl], which was reported in 1956 by Wilkinson 18 , and was subsequently authenticated structurally by Yen in 1965 (ref. 19).…”

mentioning

confidence: 99%

Reductive assembly of cyclobutadienyl and diphosphacyclobutadienyl rings at uranium

et al. 2013

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Despite the abundance of f-block-cyclopentadienyl, arene, cycloheptatrienyl and cyclooctatetraenide complexes, cyclobutadienyl derivatives are unknown in spite of their prevalence in the d-block. Here we report that reductive [2 þ 2]-cycloaddition reactions of diphenylacetylene and (2,2-dimethylpropylidyne)phosphine with uranium(V)-inverted sandwich 10p-toluene tetra-anion complexes results in the isolation of inverted sandwich cyclobutadienyl and diphosphacyclobutadienyl dianion uranium(IV) complexes. Computational analysis suggests that the bonding is predominantly electrostatic. Although the c 4 molecular orbital in the cyclobutadienyl and diphosphacyclobutadienyl ligands exhibits the correct symmetry for d-bonding to uranium, the dominant covalent contributions arise from p-bonding involving c 2 and c 3 orbital combinations. This contrasts with uranium complexes of larger arenes and cyclo-octatetraenide, where d-bonding dominates. This suggests that the angular requirements for uranium to bond to a small four-membered ring favours p-bonding, utilizing 5f-instead of 6d-orbitals, over d-bonding that is favoured with larger ligands, where 6d-orbitals can become involved in the bonding.

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π-cyclopentadienyl compounds of uranium-IV and thorium-IV

Cited by 175 publications

References 8 publications

A DFT and experimental investigation of the electron affinity of the triscyclopentadienyl uranium complexes Cp3UX

A DFT and experimental investigation of the electron affinity of the triscyclopentadienyl uranium complexes Cp3UX

Synthesis and Hydrolysis of Uranyl, Neptunyl, and Plutonyl Gas-Phase Complexes Exhibiting Discrete Actinide–Carbon Bonds

Reductive assembly of cyclobutadienyl and diphosphacyclobutadienyl rings at uranium

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