Binuclear Uranium(VI) Complexes with a “Pacman” Expanded Porphyrin: Computational Evidence for Highly Unusual Bis‐Actinyl Structures

Pan, Qing‐Jiang; Shamov, Grigory A.; Schreckenbach, Georg

doi:10.1002/chem.200902014

Cited by 44 publications

(53 citation statements)

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“…Theoretical predictions on structures and reactions of the computed uranyl complexes of H4L pac and H4L provided significant support for the experimental results. [39][40][41] Additionally, these calculations, 39,40 predicted the new butterfly-like geometry for U VI 2O4 in [(OU VI (μ-O))2(L pac )] -a different type of cation-cation interaction (CCI) 32,[42][43][44][45][46][47][48][49][50][51][52][53][54][55] to that observed so far (a CCI is defined when one actinyl metal centre is coordinated by the oxo atom of a second actinyl). Here, the occupation by one oxo of a mutually cis-coordination site was explained, since a much higher energetic barrier arises from the repulsion of the second uranyl entering into the small empty pocket of [(THF)(U VI O2)(H2L pac )], as lower than the barrier to oxo migration from trans to cis-uranyl position.…”

Section: Introductionmentioning

confidence: 89%

“…The solvent effect of pyridine was taken into account with the Conductor-Like Screening Model, COSMO. 68,69 The Klamt radii were used for the main group atoms (H = 1.30 Å, C = 2.00 Å, N = 1.83 Å and O = 1.72 Å) 70 and for the actinide atoms (U, Np and Pu = 1.70 Å) 39,40,71,72 . The scalar relativistic ZORA method [73][74][75][76] and Slater-type TZP basis sets (labeled as B-II) were used.…”

Section: Computational Detailsmentioning

confidence: 99%

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Relativistic DFT and experimental studies of mono- and bis-actinyl complexes of an expanded Schiff-base polypyrrole macrocycle

et al. 2016

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The computationally- and experimentally-determined molecular structures of a bis-uranyl(vi) complex of an expanded Schiff-base polypyrrolic macrocycle [(UO)(L)] are in close agreement only if the pyridine in the fifth equatorial donor site on the uranium is included in the calculations. The relativistic density functional theory (DFT) calculations presented here are augmented from those on previously reported simpler frameworks, and demonstrate that other augmentations, such as the incorporation of condensed-phase media and the changes in the peripheral groups of the ligand, have only a slight effect. Synthetic routes to pure samples of the bis- and mono-uranyl(vi) complexes have been developed using pyridine and arene solvents, respectively, allowing the experimental determination of the molecular structures by X-ray single crystal diffraction; these agree well with the calculated structures. A comprehensive set of calculations has been performed on a series of actinyl AnO complexes of this macrocyclic ligand. These include both bis- and mono-actinyl adducts for the metals U, Np and Pu, and formal oxidation states VI and V. The reduction potentials of the complexes for U, Np, and Pu, incorporating both solvation and spin-orbit coupling considerations, show the order Np > Pu > U. The agreement between experimental and computed data for U is excellent, suggesting that at this level of computation predictions made about the significantly more radiotoxic Np and Pu molecules should be accurate. A particularly unusual structure of the mononuclear plutonyl(v) complex was predicted by quantum chemical calculations, in which a twist in the macrocycle allows one of the two endo-oxo groups to form a hydrogen bond to one pyrrole group of the opposite side of the macrocycle, in accordance with this member of the set containing the most Lewis basic oxo groups.

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Section: Introductionmentioning

confidence: 89%

Section: Computational Detailsmentioning

confidence: 99%

Relativistic DFT and experimental studies of mono- and bis-actinyl complexes of an expanded Schiff-base polypyrrole macrocycle

et al. 2016

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“…13 The studies of Arnold 15 and one-electron reduced uranium(V) products. 16,17 Our theoretical studies 18 showed that the H 4 L 1 ligand can accommodate two uranyl ions to form bis-uranyl complexes (UO 2 ) 2 (L 1 ). Of particular interest is the fact that the two UO 2 2+ moieties exhibit the butterfly-like and T-shaped structures as seen in Chart 2.…”

Section: Introductionmentioning

confidence: 99%

“…In contrast, the aryl-linked macrocycle (H 4 L 1 ) shows energetic preference for a butterfly-like and a T-shaped bis-uranyl complex. 18…”

Section: Introductionmentioning

confidence: 99%

Theoretical predictions of cofacial bis(actinyl) complexes of a stretched Schiff-base calixpyrrole ligand

et al. 2011

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“…No hexavalent bis ‐uranyl counterpart has been found so far. Our previous theoretical study suggested that the penta valent uranyl bar is less rigid than the hexa valent one and more easily transformed to the cis ‐structure. Experimentally, Arnold and Love et al have chemically modified the aryl‐linked H 4 L Ar ligand and prepared an anthracenyl‐containing polypyrrolic macrocycle (H 4 L, Chart ) that has longer linker .…”

Section: Introductionmentioning

confidence: 99%

Infrared vibrational spectra, electronic structures, and formation reactions of polypyrrolic mono‐ and bis‐actinyl complexes: A relativistic DFT study

Zheng

Xuan

et al. 2017

Int J of Quantum Chemistry

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The development of synthetic techniques has enabled synthesis and characterization of a series of mono and bis-uranyl complexes of octadentate polypyrrolic macrocycles such as aryl-lined H 4 L Ar and anthracenyl-linked H 4 L, which is complemented by theoretical investigation via extending to more toxic and radioactive transuranics. The relativistic density functional theory (DFT) study has been dedicated to twelve actinyl complexes supported by the H 4 L ligand. The actinides include U, Np, and Pu elements, and either one or two is rendered in complexes with oxidation states of V or VI. Calculated symmetric/asymmetric An 5 O stretching vibrational frequencies show the decreasing trend along U, Np, and Pu, which is consistent with calculated bond orders. The hydrogen bonds between -yl endo-oxo and remaining hydrogen atoms of pyrrolides in mononuclear complexes cause pronounced redshift of An 5 O vibrational frequencies compared to those in binuclear complexes, so does the reduction from hexa-to pentavalent complexes. The electronic structures of actinyl complexes were calculated. For example, B-pyU VI possesses low-lying U(5f)character virtual orbitals, where f(d) and f(/) orbitals occur in low-energy region and p-type ones are residing further high; the r*(U 5 O) and r(U 5 O) orbitals are significantly split over 7 eV. The previous experimental observation that the 1:1 reactions between uranyl salts and the macrocycle tend to give a mixture of bis-and mono-uranyl complexes, with bis-the major product, has been corroborated by computational studies of the thermodynamics of the reactions. K E Y W O R D S electronic structure, polypyrrolic actinyl complexes, relativistic DFT, thermodynamic energy, vibrational spectra | I N T R O D U C T I O NIn addition to the utilization in the separation science, [1][2][3][4][5] nitrogendonor ligands such as polypyrrolic macrocycle, 2,6-bis(trazinyl)pyridine and their derivatives have greatly excited the coordination chemistry of actinides. [6][7][8][9][10][11][12][13][14][15][16][17] A flexible octadentate polypyrrolic ligand (H 4 L Ar ), [18,19] for instance, is versatile, because it can accommodate diverse metal ions ranging from actinide (An), lanthanide (Ln) to transition metal, different metal ion number, and various metal oxidation (eg, III-VI for uranium). [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] Most of actinide-containing complexes supported by the H 4 L Ar ligand adopt the intriguing "Pacman-like" structure, in contrast to a recently synthesized nonclassic one. [36] The obtained bis-uranyl polypyrrolic complexes, [(ROU V (l-O)) 2 (L Ar )] (R 5 i Pr, SiMe 3 , SnPh 3 , Sn n Bu 3 , and Lipy 3 ), [28][29][30] show one cis-uranyl and one trans-one that are bonded by the cation-cation interaction (CCI) [37][38][39][40][41][42] . It is worth noting that one uranyl unit, usually retaining linear, has to be bent to suit the small space inside the mouth of these "Pacman-like" complexes. No hexavalent bis-uranyl counterpart has been found so far. Our p...

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Binuclear Uranium(VI) Complexes with a “Pacman” Expanded Porphyrin: Computational Evidence for Highly Unusual Bis‐Actinyl Structures

Cited by 44 publications

References 93 publications

Relativistic DFT and experimental studies of mono- and bis-actinyl complexes of an expanded Schiff-base polypyrrole macrocycle

Relativistic DFT and experimental studies of mono- and bis-actinyl complexes of an expanded Schiff-base polypyrrole macrocycle

Theoretical predictions of cofacial bis(actinyl) complexes of a stretched Schiff-base calixpyrrole ligand

Infrared vibrational spectra, electronic structures, and formation reactions of polypyrrolic mono‐ and bis‐actinyl complexes: A relativistic DFT study

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