Publications by authors named "Cory J Windorff"

21 Publications

  • Page 1 of 1

Crystallographic characterization of (CHSiMe)U(BH).

Acta Crystallogr E Crystallogr Commun 2021 Apr 12;77(Pt 4):383-389. Epub 2021 Mar 12.

Department of Chemistry, University of California, Irvine, California 92697, USA.

New syntheses have been developed for the synthesis of (borohydrido-κ)tris-[η-(tri-methyl-sil-yl)cyclo-penta-dien-yl]uranium(IV), [U(BH)(CHSi)] or Cp'U(BH) (Cp' = CHSiMe) and its structure has been determined by single-crystal X-ray crystallography. This compound crystallized in the space group and the structure features three -coordinated Cp' rings and a -coordinated (BH) ligand.
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http://dx.doi.org/10.1107/S2056989021002425DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8025856PMC
April 2021

Pronounced Pressure Dependence of Electronic Transitions for Americium Compared to Isomorphous Neodymium and Samarium Mellitates.

Inorg Chem 2021 Jan 16;60(1):476-483. Epub 2020 Dec 16.

Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan Way, Tallahassee, Florida 32306, United States.

The mellitate ion is relevant in spent nuclear fuel processing and is utilized as a surrogate for studying the interactions of f elements with humic acids. A wealth of different coordination modes gives the potential for diverse structural chemistry across the actinide series. In this study, an americium mellitate, Am[(C(COO)](HO)·2HO (), has been synthesized and characterized using structural analysis and spectroscopy at ambient and elevated pressures. was then compared to isomorphous neodymium () and samarium () mellitates via bond-length analysis and pressure dependence of their Laporte-forbidden f → f transitions. Results show that the pressure dependence of the f → f transitions of is significantly greater than that observed in and , with average shifts of 21.4, 4.7, and 3.6 cm/GPa, respectively. This greater shift found in shows further evidence that the 5f orbitals are more affected than the 4f orbitals when pressure is applied to isostructural compounds.
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http://dx.doi.org/10.1021/acs.inorgchem.0c03293DOI Listing
January 2021

Exploring the Oxidation States of Neptunium with Schiff Base Coordination Complexes.

Inorg Chem 2020 Dec 25;59(24):18035-18047. Epub 2020 Nov 25.

Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan Way, Room 118 DLC, Tallahassee, Florida 32306, United States.

A pair of neptunium Schiff base coordination complexes, and { = ,'-bis[(4,4'-diethylamino)salicylidene]-1,2-phenylenediamine}, have been synthesized and analyzed by several characterization methods including single-crystal X-ray diffraction, electronic absorption, H NMR, cyclic voltammetry, and theoretical interpretation. Structural analysis reveals that and are isomorphous with the previously reported and (M = Pu, Ce, U, Th) complexes, respectively, allowing for a direct comparison across the series. The reduction of or direct synthesis from a (NpO) source shows evidence of a pentavalent neptunyl species as determined by UV/vis/NIR and H NMR spectroscopy. The synthesis of directly from a (NpO) starting material gives a similar spectrum. Theoretical analysis offers insight into the electronic structure for a better understanding of the bonding patterns and relative stability of the different oxidation states. Computational results show that the Np-L covalent interactions in are similar to those in the complex, indicating that neither the presence of the axial oxo ligands nor the oxidation state significantly modify the nature of the Np-L bonds.
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http://dx.doi.org/10.1021/acs.inorgchem.0c02455DOI Listing
December 2020

Structure and Characterization of an Americium Bis(-diethyl)dithiophosphate Complex.

Inorg Chem 2020 Nov 29;59(22):16291-16300. Epub 2020 Oct 29.

Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.

A facile synthesis of an americium complex with a sulfur-donor ligand has been developed, allowing characterization of americium bonding from multiple perspectives via several techniques. Reaction of Am with SP(OEt) yields the tetrakis complex [Am(SP(OEt))] that can be crystallized as the tetraphenylarsonium salt. Structures obtained from single crystal X-ray diffraction show bond length discrepancies from the neodymium analogue consistent with the soft-donor bond enhancement common to actinides. Solid state optical spectroscopy confirms interaction of the ligand with 5f orbitals. P nuclear magnetic reflects the minor paramagnetism of Am(III). Computational investigations through CASSCF calculations, ligand-field density functional theory, and quantum chemical topological analysis allow a quantification of covalency or orbital interaction effects via total energy density and nephelauxetic parameters, both of which indicate greater covalency in the americium species than in the neodymium analogue or the americium aquo complex.
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http://dx.doi.org/10.1021/acs.inorgchem.0c02085DOI Listing
November 2020

A Single Small-Scale Plutonium Redox Reaction System Yields Three Crystallographically-Characterizable Organoplutonium Complexes.

Inorg Chem 2020 Sep 10;59(18):13301-13314. Epub 2020 Sep 10.

Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.

An approach to obtaining substantial amounts of data from a hazardous starting material that can only be obtained and handled in small quantities is demonstrated by the investigation of a single small-scale reaction of cyclooctatetraene, CH, with a solution obtained from the reduction of Cp'Pu (Cp' = CHSiMe) with potassium graphite. This one reaction coupled with oxidation of a product has provided single-crystal X-ray structural data on three organoplutonium compounds as well as information on redox chemistry thereby demonstrating an efficient route to new reactivity and structural information on this highly radioactive element. The crystal structures were obtained from the reduction of CH by a putative Pu(II) complex, (Cp'Pu), generated in situ, to form the Pu(III) cyclooctatetraenide complex, [K(crypt)][(CH)Pu], , and the tetra(cyclopentadienyl) Pu(III) complex, [K(crypt)][Cp'Pu], . Oxidation of the sample of with Ag(I) afforded a third organoplutonium complex that has been structurally characterized for the first time, (CH)Pu, . Complexes and contain Pu sandwiched between parallel (CH) rings. The (Cp'Pu) anion in features three η-Cp' rings and one η-Cp' ring, which is a rare example of a formal Pu-C η-bond. In addition, this study addresses the challenge of small-scale synthesis imparted by radiological and material availability of transuranium isotopes, in particular that of pure metal samples. A route to an anhydrous Pu(III) starting material from the more readily available PuO was developed to facilitate reproducible syntheses and allow complete spectroscopic analysis of and . PuO was converted to PuBr(DME) (DME = CHOCHCHOCH) and subsequently PuBr(THF), which was used to independently synthesize , , and .
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http://dx.doi.org/10.1021/acs.inorgchem.0c01671DOI Listing
September 2020

Compression of curium pyrrolidine-dithiocarbamate enhances covalency.

Nature 2020 07 15;583(7816):396-399. Epub 2020 Jul 15.

Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, USA.

Curium is unique in the actinide series because its half-filled 5f  shell has lower energy than other 5f  configurations, rendering it both redox-inactive and resistant to forming chemical bonds that engage the 5f shell. This is even more pronounced in gadolinium, curium's lanthanide analogue, owing to the contraction of the 4f orbitals with respect to the 5f orbitals. However, at high pressures metallic curium undergoes a transition from localized to itinerant 5f electrons. This transition is accompanied by a crystal structure dictated by the magnetic interactions between curium atoms. Therefore, the question arises of whether the frontier metal orbitals in curium(III)-ligand interactions can also be modified by applying pressure, and thus be induced to form metal-ligand bonds with a degree of covalency. Here we report experimental and computational evidence for changes in the relative roles of the 5f/6d orbitals in curium-sulfur bonds in [Cm(pydtc)] (pydtc, pyrrolidinedithiocarbamate) at high pressures (up to 11 gigapascals). We compare these results to the spectra of [Nd(pydtc)] and of a Cm(III) mellitate that possesses only curium-oxygen bonds. Compared with the changes observed in the [Cm(pydtc)] spectra, we observe smaller changes in the f-f transitions in the [Nd(pydtc)] absorption spectrum and in the f-f emission spectrum of the Cm(III) mellitate upon pressurization, which are related to the smaller perturbation of the nature of their bonds. These results reveal that the metal orbital contributions to the curium-sulfur bonds are considerably enhanced at high pressures and that the 5f orbital involvement doubles between 0 and 11 gigapascal. Our work implies that covalency in actinides is complex even when dealing with the same ion, but it could guide the selection of ligands to study the effect of pressure on actinide compounds.
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http://dx.doi.org/10.1038/s41586-020-2479-2DOI Listing
July 2020

Pressure-Induced Spectroscopic Changes in a Californium 1D Material Are Twice as Large as Found in the Holmium Analog.

Inorg Chem 2020 Aug 10;59(15):10794-10801. Epub 2020 Jul 10.

Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.

In this study, the synthesis, characterization, and pressure response of a 1D californium mellitate (mellitate = 1,2,3,4,5,6-benzenehexacarboxylate) coordination polymer, Cf(mell)(HO)·4HO (), are reported. The Cf-O lengths within the crystal structure are compared to its gadolinium () and holmium () analogs as well. These data show that the average Cf-O bond distance is slightly longer than the average Gd-O bond, consistent with trends in effective ionic radii. UV-vis-NIR absorption spectra as a function of pressure were collected using diamond-anvil techniques for both and . These experiments show that the Cf(III) f → f transitions have a stronger dependence on pressure than that of the holmium analog. In the former case, the shift is nearly linear with applied pressure and averages 6.6 cm/GPa, whereas in the latter, it is <3 cm/GPa.
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http://dx.doi.org/10.1021/acs.inorgchem.0c01290DOI Listing
August 2020

Examination of Molten Salt Reactor Relevant Elements Using Hydrothermal Synthesis.

Inorg Chem 2020 Apr 26;59(7):4176-4180. Epub 2020 Mar 26.

Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan Way, Room 188 DLC, Tallahassee, Florida 32306, United States.

The structural chemistry of elements relevant to the FLiBe molten salt reactor, Th, U, Np, and Zr, including Ce and Nd (as analogues for Pu and Am, respectively), have been examined using hydrothermal synthesis at 200 °C. These reactions serve to model the reaction of molten salts under hydrolysis conditions. The results show that U and Np formed , while Ce formed . The source of U also controlled the crystal quality, where UO gave small crystals, while UO·2HO gave very large crystals. It is likely that Be incorporation was not observed because of the high solubility of [BeF] in water. Zr formed a third product, , which features isolated [BeF] and [ZrF] units bridged by Li. Additionally, was regularly isolated. When little to no alkali metal was included in the reaction, was isolated for Np, U, and Ce.
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http://dx.doi.org/10.1021/acs.inorgchem.0c00360DOI Listing
April 2020

Structural and Spectroscopic Investigation of Two Plutonium Mellitates.

Inorg Chem 2020 Mar 10;59(5):3085-3090. Epub 2020 Feb 10.

Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.

The aqueous reaction of mellitic acid (Hmell) with PuBr·HO forms two plutonium mellitates, Pu(mell)(HO)·HO () and Pu(mell)(HO)·2HO (). These compounds are compared to the isomorphous lanthanide mellitates with similar ionic radii via bond length analysis. Both plutonium compounds form three-dimensional metal-organic frameworks, with having two unique metal centers and having one. All plutonium metal centers exhibit nine-coordinate geometries. Our results show metal-oxygen bond lengths for plutonium significantly shorter than those of the previously reported lanthanum and herein reported cerium analogues, consistent with the nine-coordinate ionic radii. Clear Laporte-forbidden 5f → 5f transitions are observed in the ultraviolet-visible-near-infrared spectra and are assigned to trivalent plutonium. However, there is a distinct color difference between the two plutonium compounds.
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http://dx.doi.org/10.1021/acs.inorgchem.9b03432DOI Listing
March 2020

Probing a variation of the inverse-trans-influence in americium and lanthanide tribromide tris(tricyclohexylphosphine oxide) complexes.

Chem Sci 2020 Feb 5;11(10):2770-2782. Epub 2020 Feb 5.

Department of Chemistry and Biochemistry, Florida State University 95 Chieftan Way, RM. 118 DLC Tallahassee Florida 32306 USA

The synthesis, characterization, and theoretical analysis of meridional americium tribromide tris(tricyclohexylphosphine oxide), , has been achieved and is compared with its early lanthanide (La to Nd) analogs. The data show that homo ligands display significantly shorter bonds than the or hetero ligands. This is particularly pronounced in the americium compound. DFT along with multiconfigurational CASSCF calculations show that the contraction of the bonds relates qualitatively with overall covalency, americium shows the most covalent interactions compared to lanthanides. However, the involvement of the 5p and 6p shells in bonding follows a different order, namely cerium > neodymium ∼ americium. This study provides further insight into the mechanisms by which ITI operates in low-valent f-block complexes.
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http://dx.doi.org/10.1039/c9sc05268bDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8157511PMC
February 2020

Synthesis, Spectroscopy, and Theoretical Details of Uranyl Schiff-Base Coordination Complexes.

Inorg Chem 2020 Jan 22;59(1):23-31. Epub 2019 Apr 22.

Department of Chemistry and Biochemistry , Florida State University , 95 Chieftan Way, Room 118 DLC , Tallahassee , Florida 32306 , United States.

Two uranyl Schiff-base coordination complexes, and {L = ,'-bis[(4,4'-diethylamino)salicylidene]-1,2-phenylenediamine}, have been synthesized that feature a rigid phenyl backbone. These complexes have been characterized by structural, spectroscopic, and theoretical analysis to offer an electronic structure basis to explain the bonding parameters and stability. Single-crystal X-ray analysis reveals that adopts the typical "soft taco confirmation" characteristic of uranyl salophen complexes, whereas features an unusual neutral ligand coordination that contains an internal hydrogen bond between the phenol and imine. Rate constants calculated from electrochemical experiments confirm a quasi-reversible UO/UO couple. Single-configurational and multiconfigurational methods were used to explore the bonding in and . For , the U-Cl bond exhibits more covalent contributions than U-O.
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http://dx.doi.org/10.1021/acs.inorgchem.9b00477DOI Listing
January 2020

Electronic, Magnetic, and Theoretical Characterization of (NH)UF, a Simple Molecular Uranium(IV) Fluoride.

Inorg Chem 2019 Jan 20;58(1):637-647. Epub 2018 Dec 20.

Department of Chemistry and Biochemistry , Florida State University , Tallahassee , Florida 32306 , United States.

The simple system of tetraammonium octafluorouranate is employed to derive a fundamental understanding of the uranium-fluorine interaction. The structure is composed of isolated molecules, enabling a detailed examination of the U ( f) ion. Characterization of single-crystals by X-ray diffraction, absorption spectroscopy, and magnetic analysis up to 45 T is combined with extensive theoretical treatment by CASSCF. The influence of different active spaces and representations of the structure is examined in the context of the experimental evidence. The Interacting Quantum Atoms method (IQA) is used to examine the nature of the U-F bond, concluding that there is a non-negligible degree of covalent character (9% of the total bond energy) in [UF]. For the structural and theoretical reasons discussed herein, it is proposed that the structure of (NH)UF may be appropriately employed as a benchmark compound for future theoretical characterization of U(IV).
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http://dx.doi.org/10.1021/acs.inorgchem.8b02800DOI Listing
January 2019

Experimental and Theoretical Comparison of Transition-Metal and Actinide Tetravalent Schiff Base Coordination Complexes.

Inorg Chem 2018 Dec 30;57(24):15389-15398. Epub 2018 Nov 30.

Department of Chemistry and Biochemistry , Florida State University , 95 Chieftan Way, RM. 118 DLC , Tallahassee , Florida 32306 , United States.

A series of homoleptic tetravalent transition-metal and actinide Schiff-base coordination complexes, ML {M = Zr, Hf, Th, U; L = N, N'-bis[(4,4'-diethylamino)salicylidene]-1,2-phenylenediamine}, have been synthesized that feature a rigid phenyl backbone. These complexes create the opportunity for comparing a series of complexes containing metal cations in the formal IV+ oxidation state by structural, spectroscopic, and theoretical analysis that also incorporate the previously reported Ce(IV) and Pu(IV) analogues. X-ray crystallographic analysis reveals that all complexes are isomorphous and feature a co-facial ligand geometry. TD-DFT and other quantum mechanical methods were used to explore bonding differences across between the complexes, and resulting calculated absorbance spectra for ML are in good agreement with the experimental data. The computational results also suggest that U(IV) and Pu(IV) analogs have more covalent character in their bonding than found with the other metal cations reported here.
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http://dx.doi.org/10.1021/acs.inorgchem.8b02700DOI Listing
December 2018

Synthesis of uranium-in-cryptand complexes.

Chem Commun (Camb) 2018 Sep;54(73):10272-10275

Department of Chemistry, University of California-Irvine, Irvine, California 92697, USA.

The facile encapsulation of U(iii) and La(iii) by 2.2.2-cryptand (crypt) using simple starting materials is described. Addition of crypt to UI3 and LaCl3 forms the crystallographically-characterizable complexes, [U(crypt)I2]I and [La(crypt)Cl2]Cl. In the presence of water, the U(iii)-aquo adducts, [U(crypt)I(OH2)][I]2 and [U(crypt)I(OH2)][I][BPh4], can be isolated.
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http://dx.doi.org/10.1039/c8cc05341cDOI Listing
September 2018

Schiff-base coordination complexes with plutonium(iv) and cerium(iv).

Chem Commun (Camb) 2018 Aug 18;54(62):8634-8636. Epub 2018 Jul 18.

Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan Way, RM. 118 DLC, Tallahassee, Florida 32306, USA.

PuL and CeL (L = N,N'-bis[(4,4'-diethylamino)salicylidene]-1,2-phenylenediamine) have been synthesized, and characterized by single crystal X-ray diffraction, UV/vis/NIR spectroscopy, and cyclic voltammetry. These studies reveal the enhanced stabilization of Pu(iv) versus Ce(iv) with this Schiff base, and quasi-reversible redox behaviour only with the plutonium complex.
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http://dx.doi.org/10.1039/c8cc03571gDOI Listing
August 2018

Identification of the Formal +2 Oxidation State of Neptunium: Synthesis and Structural Characterization of {Np[CH(SiMe)]}.

J Am Chem Soc 2018 06 5;140(24):7425-7428. Epub 2018 Jun 5.

Department of Chemistry , University of California-Irvine , Irvine , California 92697-2025 , United States.

We report a new formal oxidation state for neptunium in a crystallographically characterizable molecular complex, namely Np in [K(crypt)][NpCp″] [crypt = 2.2.2-cryptand, Cp″ = CH(SiMe)]. Density functional theory calculations indicate that the ground state electronic configuration of the Np ion in the complex is 5f6d.
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http://dx.doi.org/10.1021/jacs.8b03907DOI Listing
June 2018

Small-Scale Metal-Based Syntheses of Lanthanide Iodide, Amide, and Cyclopentadienyl Complexes as Analogues for Transuranic Reactions.

Inorg Chem 2017 Oct 15;56(19):11981-11989. Epub 2017 Sep 15.

Department of Chemistry, University of California , Irvine, California 92697, United States.

Small-scale reactions of the Pu analogues La, Ce, and Nd have been explored in order to optimize reaction conditions for milligram scale reactions of radioactive plutonium starting from the metal. Oxidation of these lanthanide metals with iodine in ether and pyridine has been studied, and LnI(EtO) (1-Ln; x = 0.75-1.9) and LnI(py) (2-Ln; py = pyridine, NCH) have been synthesized on scales ranging from 15 mg to 2 g. The THF adducts LnI(THF) (3-Ln) were synthesized by dissolving 1-Ln in THF. The viability of these small-scale samples as starting materials for amide and cyclopentadienyl f-element complexes was tested by reacting KN(SiMe), KCp' (Cp' = CHSiMe), KCp'' (Cp'' = CH(SiMe)-1,3), and KCMeH with 1-Ln generated in situ. These reactions produced Ln[N(SiMe)] (4-Ln), Cp'Ln (5-Ln), Cp″Ln (6-Ln), and (CMeH)Ln (7-Ln), respectively. Small-scale samples of Cp'Ce (5-Ce) and Cp'Nd (5-Nd) were reduced with potassium graphite (KC) in the presence of 2.2.2-cryptand to check the viability of generating the crystallographically characterizable Ln complexes [K(2.2.2-cryptand)][Cp'Ln] (8-Ln; Ln = Ce, Nd).
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http://dx.doi.org/10.1021/acs.inorgchem.7b01968DOI Listing
October 2017

Covalency in Americium(III) Hexachloride.

J Am Chem Soc 2017 06 14;139(25):8667-8677. Epub 2017 Jun 14.

Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.

Developing a better understanding of covalency (or orbital mixing) is of fundamental importance. Covalency occupies a central role in directing chemical and physical properties for almost any given compound or material. Hence, the concept of covalency has potential to generate broad and substantial scientific advances, ranging from biological applications to condensed matter physics. Given the importance of orbital mixing combined with the difficultly in measuring covalency, estimating or inferring covalency often leads to fiery debate. Consider the 60-year controversy sparked by Seaborg and co-workers ( Diamond, R. M.; Street, K., Jr.; Seaborg, G. T. J. Am. Chem. Soc. 1954 , 76 , 1461 ) when it was proposed that covalency from 5f-orbitals contributed to the unique behavior of americium in chloride matrixes. Herein, we describe the use of ligand K-edge X-ray absorption spectroscopy (XAS) and electronic structure calculations to quantify the extent of covalent bonding in-arguably-one of the most difficult systems to study, the Am-Cl interaction within AmCl. We observed both 5f- and 6d-orbital mixing with the Cl-3p orbitals; however, contributions from the 6d-orbitals were more substantial. Comparisons with the isoelectronic EuCl indicated that the amount of Cl 3p-mixing with Eu 5d-orbitals was similar to that observed with the Am 6d-orbitals. Meanwhile, the results confirmed Seaborg's 1954 hypothesis that Am 5f-orbital covalency was more substantial than 4f-orbital mixing for Eu.
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http://dx.doi.org/10.1021/jacs.7b03755DOI Listing
June 2017

Synthesis, Structure, and Reactivity of the Sterically Crowded Th Complex (CMe)Th Including Formation of the Thorium Carbonyl, [(CMe)Th(CO)][BPh].

J Am Chem Soc 2017 03 27;139(9):3387-3398. Epub 2017 Feb 27.

Department of Chemistry, University of California , Irvine, California 92697-2025, United States.

The Th complex, (CMe)Th, has been isolated despite the fact that tris(pentamethylcyclopentadienyl) complexes are highly reactive due to steric crowding and few crystallographically characterizable Th complexes are known due to their highly reducing nature. Reaction of (CMe)ThMe with [EtNH][BPh] produces the cationic thorium complex [(CMe)ThMe][BPh] that can be treated with KCMe to generate (CMe)ThMe, 1. The methyl group on (CMe)ThMe can be removed with [EtNH][BPh] to form [(CMe)Th][BPh], 2, the first cationic tris(pentamethylcyclopentadienyl) metal complex, which can be reduced with KC to yield (CMe)Th, 3. Complexes 1-3 have metrical parameters consistent with the extreme steric crowding that previously has given unusual (CMe) reactivity to (CMe)M complexes in reactions that form less crowded (CMe)M-containing products. However, neither sterically induced reduction nor (η-CMe) reactivity is observed for these complexes. (CMe)Th, which has a characteristic EPR spectrum consistent with a d ground state, has the capacity for two-electron reduction via Th and sterically induced reduction. However, it reacts with MeI to make two sterically more crowded complexes, (CMe)ThI, 4, and (CMe)ThMe, 1, rather than (CMe)Th(Me)I. Complex 3 also forms more crowded complexes in reactions with I, PhCl, and AlMe, which generate (CMe)ThI, (CMe)ThCl, and (CMe)ThMe, 1, respectively. The reaction of (CMe)Th, 3, with H forms the known (CMe)ThH as the sole thorium-containing product. Surprisingly, (CMe)ThH is also observed when (CMe)Th is combined with 1,3,5,7-cyclooctatetraene. [(CMe)Th][BPh] reacts with tetrahydrofuran (THF) to make [(CMe)Th(THF)][BPh], 2-THF, which is the first (CMe)M of any kind that does not have a trigonal planar arrangement of the (CMe) rings. It is also the first (CMe)M complex that does not ring-open THF. [(CMe)Th][BPh], 2, reacts with CO to generate a product characterized as [(CMe)Th(CO)][BPh], 5, the first example of a molecular thorium carbonyl isolable at room temperature. These results have been analyzed using density functional theory calculations.
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http://dx.doi.org/10.1021/jacs.6b10826DOI Listing
March 2017

Identification of the Formal +2 Oxidation State of Plutonium: Synthesis and Characterization of {Pu[CH(SiMe)]}.

J Am Chem Soc 2017 03 13;139(11):3970-3973. Epub 2017 Mar 13.

Department of Chemistry, University of California , Irvine, California 92697-2025, United States.

Over 70 years of chemical investigations have shown that plutonium exhibits some of the most complicated chemistry in the periodic table. Six Pu oxidation states have been unambiguously confirmed (0 and +3 to +7), and four different oxidation states can exist simultaneously in solution. We report a new formal oxidation state for plutonium, namely Pu in [K(2.2.2-cryptand)][PuCp″], Cp″ = CH(SiMe). The synthetic precursor PuCp″ is also reported, comprising the first structural characterization of a Pu-C bond. Absorption spectroscopy and DFT calculations indicate that the Pu ion has predominantly a 5f electron configuration with some 6d mixing.
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http://dx.doi.org/10.1021/jacs.7b00706DOI Listing
March 2017

Expanding the Chemistry of Molecular U(2+) Complexes: Synthesis, Characterization, and Reactivity of the {[C5 H3 (SiMe3 )2 ]3 U}(-) Anion.

Chemistry 2016 Jan 4;22(2):772-82. Epub 2015 Dec 4.

Department of Chemistry, University of California-Irvine, Irvine, CA 92697 (USA).

The synthesis of new molecular complexes of U(2+) has been pursued to make comparisons in structure, physical properties, and reactivity with the first U(2+) complex, [K(2.2.2-cryptand)][Cp'3 U], 1 (Cp'=C5 H4 SiMe3 ). Reduction of Cp''3 U [Cp''=C5 H3 (SiMe3 )2 ] with KC8 in the presence of 2.2.2-cryptand or 18-crown-6 generates [K(2.2.2-cryptand)][Cp''3 U], 2-K(crypt), or [K(18-crown-6)(THF)2 ][Cp''3 U], 2-K(18c6), respectively. The UV/Vis spectra of 2-K and 1 are similar, and they are much more intense than those of U(3+) analogues. Variable temperature magnetic susceptibility data for 1 and 2-K(crypt) reveal lower room temperature χM T values relative to the experimental values for the 5f(3) U(3+) precursors. Stability studies monitored by UV/Vis spectroscopy show that 2-K(crypt) and 2-K(18c6) have t1/2 values of 20 and 15 h at room temperature, respectively, vs. 1.5 h for 1. Complex 2-K(18c6) reacts with H2 or PhSiH3 to form the uranium hydride, [K(18-crown-6)(THF)2 ][Cp''3 UH], 3. Complexes 1 and 2-K(18c6) both reduce cyclooctatetraene to form uranocene, (C8 H8 )2 U, as well as the U(3+) byproducts [K(2.2.2-cryptand)][Cp'4 U], 4, and Cp''3 U, respectively.
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http://dx.doi.org/10.1002/chem.201503583DOI Listing
January 2016