Preparation, solution dynamics, and x-ray structure of bis(pentamethylcyclopentadienyl)actinide complexes of chelating phosphorus ylides

Cramer, Roger E.; Roth, Steven.; Edelmann, Frank T.; Bruck, Michael A.; Cohn, Kim; Gilje, John W.

doi:10.1021/om00107a011

Cited by 43 publications

(16 citation statements)

References 5 publications

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“…This angle is smaller as compared to the non-bridge uranium complexes (133-138u). 8,[37][38][39][40] The uranium atom is bonded to four bridging chloride ligands for which two bonds are much longer than the other two: U-Cl( 1…”

Section: Introductionmentioning

confidence: 99%

Recent advances in organothorium and organouranium catalysis

2008

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In this critical review we summarize the latest results obtained during the last decade concerning the catalytic activities of organoactinide complexes. We begin with a brief summary of the synthesis and characterization of uranium and thorium complexes that later will be used as catalysts for demanding chemical transformations. Hydroamination, hydrosilylation of terminal alkynes, coupling of terminal alkynes with isonitriles, catalytic reduction of azides and hydrazines, ring opening polymerization of cyclic esters and polymerization of alpha-olefins are covered in this review (118 references). The topics covered in this review regarding organoactinide chemistry will be of interest to inorganic, organic and organometallic chemists, material and catalytic scientists due to its unique mode of activation as compared to late transition-metals. In addition, the field of organoactinide complexes in catalysis is steadily growing, because of the complementary reactivity of organoactinides as compared to other early or late transition complexes, in demanding chemical transformations.

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Section: Introductionmentioning

confidence: 99%

Recent advances in organothorium and organouranium catalysis

2008

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“…[1][2][3] Recently, we reported that benzonitrile inserts into the actinide-carbon bonds in complexes of the type (C 5 Me 5 ) 2 AnR 2 to afford bis(ketimide) complexes (C 5 Me 5 ) 2 An[-NdC(Ph)(R)] 2 (where An ) Th, R ) Ph, CH 2 Ph, CH 3 ; An ) U, R ) CH 2 Ph, CH 3 ) and determined through structural, electrochemical, and spectroscopic studies that the An-N interactions in these complexes possessed bond orders greater than one. [3][4][5] As few systematic studies on the electronic structures across a homologous series of actinide complexes have been reported, [6][7][8][9] we were interested in exploiting the (C 5 Me 5 ) 2 An bis(ketimide) framework to prepare a series of complexes from fluorinated nitriles to tune electronic properties of the resulting complexes.…”

Section: Introductionmentioning

confidence: 99%

Systematic Studies of Early Actinide Complexes: Thorium(IV) Fluoroketimides

et al. 2007

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Reaction of (C5Me5)2Th(CH3)2 with 2 equiv of NC-ArF gives the corresponding fluorinated thorium(IV) bis(ketimide) complexes (C5Me5)2Th[-N=C(CH3)(ArF)]2 (where ArF = 3-F-C6H4 (4), 4-F-C6H4 (5), 2-F-C6H4 (6), 3,5-F2-C6H3 (7), 3,4,5-F3-C6H2 (8), 2,6-F2-C6H3 (9), 2,4,6-F3-C6H2 (10), and C6F5 (11)). The complexes have been characterized by a combination of single-crystal X-ray diffraction, cyclic voltammetry and NMR, and UV-visible absorption and low-temperature luminescence spectroscopies. Density functional theory (DFT) and time-dependent DFT (TD-DFT) results are reported for complexes 5, 11, and (C5Me5)2Th[-N=C(Ph)2]2 (1) for comparison with experimental data and to guide in the interpretation of the spectroscopic results. The most significant structural perturbation imparted by the fluorine substitution in these complexes is a rotation of the fluorophenyl group (ArF) out of the plane defined by the N=C(CMe)(Cipso) fragment in complexes 9-11 when the ArF group possesses two ortho fluorine atoms. Excellent agreement is obtained between the optimized ground state DFT calculated structures and crystal structures for 11, which displays the distortion, as well as 5, which does not. In complexes 9-11, the out-of-plane rotation results in large interplanar angles (phi) between the planes formed by ketimide atoms N=C(CMe)(Cipso) and the ketimide aryl groups in the range phi = 49.1-88.8 degrees , while in complexes 5, 7, and 8, phi = 5.7-34.9 degrees . The large distortions in 9-11 are a consequence of an unfavorable steric interaction between one of the two ortho fluorine atoms and the methyl group [-N=C(CH3)] on the ketimide ligand. Excellent agreement is also observed between the experimental electronic spectroscopic data and the TD-DFT predictions that the two lowest lying singlet states are principally of nonbonding nitrogen p orbital to antibonding C=N pi* orbital (pN-->pi*C=N or npi*) character, giving rise to moderately intense transitions in the mid-visible spectral region that are separated in energy by less than 0.1 eV. Low-temperature (77 K) luminescence from both singlet and triplet excited states are also observed for these complexes. Emission lifetime data at 77 K for the triplet states are in the range 50-400 mus. These emission spectral data also exhibit vibronic structure indicative of a small Franck-Condon distortion in the ketimide M-N=C(R1)(R2) linkage. Consistent with this vibronic structure, resonance enhanced Raman vibrational scattering is also observed for (C5Me5)2Th[-N=C(Ph)(CH2Ph)]2 (2) when exciting into the visible excited states. These systems represent rare examples of Th(IV) complexes that engender luminescence and resonance Raman spectral signatures.

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“…† The U-C(108) distance of 2.752(11) Å is significantly longer than any other U-C s-bond hitherto recorded; the usual range is ca. 2.4-2.55 Å, 12 although distances of ca. 2.60 Å have been measured in complexes of chelating phosphorus ylids.…”

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confidence: 99%