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Wang S, Wang D, Heng Y, Li T, Ding W, Zi G, Walter MD. Synthesis and Structure of [η 5-1,2,4-(Me 3Si) 3C 5H 2] 2Th(bipy) and Its Reactivity toward Small Molecules. Inorg Chem 2024; 63:7473-7492. [PMID: 38591749 DOI: 10.1021/acs.inorgchem.4c00635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Abstract
Halide exchange of (Cp3tms)2ThCl2 (1; Cp3tms = η5-1,2,4-(Me3Si)3C5H2) with Me3SiI furnishes (Cp3tms)2ThI2 (2), which is then reduced with potassium graphite (KC8) in the presence of 2,2'-bipyridine to give the thorium bipyridyl metallocene (Cp3tms)2Th(bipy) (3) in good yield. Complex 3 was fully characterized and readily reacted with various small molecules. For example, 3 may serve as a synthetic equivalent for the (Cp3tms)2Th(II) fragment when exposed to CuI, Ph2S2, organic azides, and CS2. Moreover, upon the addition of thiobenzophenone Ph2CS, p-methylbenzaldehyde (p-MeC6H4)CHO, benzophenone Ph2CO, amidate PhCONH(p-tolyl), seleno-ketone (p,p'-dimethoxy), selenobenzophenone (p-MeOPh)2CSe, di(p-tolyl)methanimine (p-tolyl)2C═NH, 1,2-di(benzylidene)hydrazine (PhCH═N)2, and nitriles PhCN, PhCH2CN, and Ph2CHCN C-C coupling results to give (Cp3tms)2Th[(bipy)(Ph2CS)] (8), (Cp3tms)2Th[(bipy)(p-MePhCHO)] (9), (Cp3tms)2Th[(bipy)(Ph2CO)] (10), (Cp3tms)2Th[(bipy){(p-tolylNH)(Ph)CO}] (11), (Cp3tms)2Th[(bipy){(p-MeOPh)2CSe}] (12), (Cp3tms)2Th[(bipy){(p-tolyl)2CNH}] (13), (Cp3tms)2Th[(bipy)(PhCHNN═CHPh)] (14), (Cp3tms)2Th[(bipy)(PhCN)] (16), (Cp3tms)2Th[(bipy)(PhCH2CN)] (17), and (Cp3tms)2Th[(bipy)(Ph2CHCN)] (18), respectively. However, when thiazole is added to 3, the dimeric sulfido complex [(Cp3tms)2Th]2[μ-(bipy)CH2NCHCHS]2 (15) can be isolated. Moreover, the addition of isonitriles such as Me3CNC and PhCH2NC to 3 results in C-N bond cleavage and C-C coupling processes to form the thorium isocyanido amido complexes (Cp3tms)2Th[4-(Me3C)bipy](NC) (19) and (Cp3tms)2Th[4-(PhCH2)bipy](NC) (20), respectively. Nevertheless, upon exposure of 3 to (trimethylsilyl)diazomethane Me3SiCHN2, the bis-amido complex (Cp3tms)2Th[5,6-(Me3SiCH)bipy] (21), concomitant with N2 release, is isolated.
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Affiliation(s)
- Shichun Wang
- Department of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Dongwei Wang
- Department of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Yi Heng
- Department of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Tongyu Li
- Department of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Wanjian Ding
- Department of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Guofu Zi
- Department of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Marc D Walter
- Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, Braunschweig 38106, Germany
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Nguyen JQ, Wedal JC, Ziller JW, Furche F, Evans WJ. Investigating Steric and Electronic Effects in the Synthesis of Square Planar 6d 1 Th(III) Complexes. Inorg Chem 2024; 63:6217-6230. [PMID: 38502000 DOI: 10.1021/acs.inorgchem.3c04462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
The factors affecting the formation and crystal structures of unusual 6d1 Th(III) square planar aryloxide complexes, as exemplified by [Th(OArMe)4]1- (OArMe = OC6H2tBu2-2,6-Me-4), were explored by synthetic and reduction studies of a series of related Th(IV) tetrakis(aryloxide) complexes, Th(OArR)4 (OArR = OC6H2tBu2-2,6-R-4). Specifically, electronic, steric, and countercation effects were explored by varying the aryloxide ligand, the alkali metal reducing agent, and the alkali metal chelating agent. Salt metathesis reactions between ThBr4(DME)2 (DME = 1,2-dimethoxyethane) and 4 equiv of the appropriate potassium aryloxide salt were used to prepare a series of Th(IV) aryloxide complexes in high yields: Th(OArH)4 (OArH = OC6H3tBu2-2,6), Th(OArtBu)4 (OArtBu = OC6H2tBu3-2,4,6), Th(OArOMe)4 (OArOMe = OC6H2tBu2-2,6-OMe-4), and Th(OArPh)4 (OArPh = OC6H2tBu2-2,6-Ph-4). Th(OArH)4 can be reduced by KC8, Na, or Li in the absence or presence of 2.2.2-cryptand (crypt) or 18-crown-6 (crown) to form dark purple solutions that have EPR and UV-visible spectra similar to those of the square planar Th(III) complex, [Th(OArMe)4]1-. Hence, the para position of the aryloxide ligand does not have to be alkylated to obtain the Th(III) complexes. Furthermore, reduction of Th(OArOMe)4, Th(OArtBu)4, and Th(OArPh)4 with KC8 in THF generated purple solutions with EPR and UV-visible spectra that are similar to those of the previously reported Th(III) anion, [Th(OArMe)4]1-. Although many of these reduction reactions did not produce single crystals suitable for study by X-ray diffraction, reduction of Th(OArH)4, Th(OArtBu)4, and Th(OArOMe)4 with Li provided X-ray quality crystals whose structures had square planar coordination geometries. Reduction of Th(OArPh)4 with Li also gave a product with EPR and UV-visible spectra that matched those of [Th(OArMe)4]1-, but X-ray quality crystals of the reduction product were too unstable to provide data. Neither Th(Odipp)4(THF)2 (Odipp = OC6H3iPr2-2,6) nor Th(Odmp)4(THF)2 (Odmp = OC6H3Me2-2,6) could be reduced to Th(III) products under similar conditions. Reduction of U(OArH)3(THF) with KC8 in the presence of 2.2.2-cryptand (crypt) was examined for comparison and formed [K(crypt)][U(OArH)4], which has a tetrahedral arrangement of the aryloxide ligands. Moreover, no further reduction was observed when either [K(crypt)][U(OArH)4] or [K(crown)(THF)2][U(OArH)4] were treated with KC8 or Li.
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Affiliation(s)
- Joseph Q Nguyen
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025, United States
| | - Justin C Wedal
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025, United States
| | - Joseph W Ziller
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025, United States
| | - Filipp Furche
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025, United States
| | - William J Evans
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025, United States
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Wedal JC, Moore WNG, Lukens WW, Evans WJ. Perplexing EPR Signals from 5f 36d 1 U(II) Complexes. Inorg Chem 2024; 63:2945-2953. [PMID: 38279200 DOI: 10.1021/acs.inorgchem.3c03449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2024]
Abstract
Metal complexes with unpaired electrons in orbitals of different angular momentum quantum numbers (e.g., f and d orbitals) are unusual and opportunities to study the interactions among these electrons are rare. X-band electron paramagnetic resonance (EPR) data were collected at <10 and 77 K on 10 U(II) complexes with 5f36d1 electron configurations and on some analogous Ce(II), Pr(II), and Nd(II) complexes with 4fn5d1 electron configurations. The U(II) compounds unexpectedly display similar two-line axial signals with g|| = 2.04 and g⊥ = 2.00 at 77 K. In contrast, U(II) complexes with 5f4 configurations are EPR-silent. Unlike U(II), the congenic 4f35d1 Nd(II) complex is EPR-silent. The Ce(II) complex with a 4f15d1 configuration is also EPR-silent, but a signal is observed for the Pr(II) complex, which has a 4f25d1 configuration. Whether or not an EPR signal is expected for these complexes depends on the coupling between f and d electrons. Since the coupling in U(II) systems is expected to be sufficiently strong to preclude an EPR signal from compounds with a 5f36d1 configuration, the results are viewed as unexplained phenomena. However, they do show that 5f36d1 U(II) samples can be differentiated from 5f4 U(II) complexes by EPR spectroscopy.
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Affiliation(s)
- Justin C Wedal
- Department of Chemistry, University of California Irvine, Irvine, California 92697, United States
| | - William N G Moore
- Department of Chemistry, University of California Irvine, Irvine, California 92697, United States
| | - Wayne W Lukens
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - William J Evans
- Department of Chemistry, University of California Irvine, Irvine, California 92697, United States
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Moore WNG, White JRK, Wedal JC, Furche F, Evans WJ. Reduction of Rare-Earth Metal Complexes Induced by γ Irradiation. Inorg Chem 2022; 61:17713-17718. [DOI: 10.1021/acs.inorgchem.2c02857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- William N. G. Moore
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Jessica R. K. White
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Justin C. Wedal
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Filipp Furche
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - William J. Evans
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
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Wedal JC, Ziller JW, Furche F, Evans WJ. Synthesis and Reduction of Heteroleptic Bis(cyclopentadienyl) Uranium(III) Complexes. Inorg Chem 2022; 61:7365-7376. [PMID: 35504019 DOI: 10.1021/acs.inorgchem.2c00322] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Heteroleptic U(III) complexes supported by bis(cyclopentadienyl) frameworks have been synthesized to examine their suitability as precursors to U(II) complexes. The newly synthesized (C5Me5)2U(OC6H2tBu2-2,6-Me-4), (C5Me5)2U(OC6H2Ad2-2,6-tBu-4) (Ad = 1-adamantyl), (C5Me5)2U(C5H5), and (C5Me5)2U(C5Me4H) are compared with (C5Me5)2U[N(SiMe3)2], (C5Me5)2U[CH(SiMe3)2], and (C5Me5)U[N(SiMe3)2]2. An improved synthesis of (C5Me5)2U(μ-Ph)2BPh2 was developed, which was used to synthesize (C5Me5)2U(C5Me4H). Since the X-ray crystal structure of (C5Me5)2U(OC6H2tBu2-2,6-Me-4) contained two very different molecules in the asymmetric unit with 115.7(5)° and 166.0(5)° U-O-Cipso angles, the (C5Me4H)2U(OC6H2tBu2-2,6-Me-4) and (C5Me5)2Ce(OC6H2tBu2-2,6-Me-4) analogues were synthesized and characterized by X-ray diffraction for comparison. Electrochemical studies in THF with a 100 mM [nBu4N][BPh4] supporting electrolyte showed U(IV)/U(III) and U(III)/U(II) redox couples for all the heteroleptic complexes except (C5Me5)2U(C5H5). Chemical reduction of all heteroleptic compounds formed dark blue solutions characteristic of U(II) when reacted with KC8 at -78 °C, but none formed isolable U(II) complexes. The targeted U(II) complexes, [(C5Me5)2U(OC6H2tBu2-2,6-Me-4)]1-, {(C5Me5)2U[CH(SiMe3)2]}1-, [(C5Me5)2U(C5H5)]1-, and [(C5Me5)2U(C5Me4H)]1-, were analyzed by density functional theory, and a 5f36d1 electron configuration was found to be the ground state in each case.
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Affiliation(s)
- Justin C Wedal
- Department of Chemistry, University of California Irvine, Irvine, California 92697, United States
| | - Joseph W Ziller
- Department of Chemistry, University of California Irvine, Irvine, California 92697, United States
| | - Filipp Furche
- Department of Chemistry, University of California Irvine, Irvine, California 92697, United States
| | - William J Evans
- Department of Chemistry, University of California Irvine, Irvine, California 92697, United States
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Straub MD, Ouellette ET, Boreen MA, Britt RD, Chakarawet K, Douair I, Gould CA, Maron L, Del Rosal I, Villarreal D, Minasian SG, Arnold J. A Uranium(II) Arene Complex That Acts as a Uranium(I) Synthon. J Am Chem Soc 2021; 143:19748-19760. [PMID: 34787416 DOI: 10.1021/jacs.1c07854] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Two-electron reduction of the amidate-supported U(III) mono(arene) complex U(TDA)3 (2) with KC8 yields the anionic bis(arene) complex [K[2.2.2]cryptand][U(TDA)2] (3) (TDA = N-(2,6-di-isopropylphenyl)pivalamido). EPR spectroscopy, magnetic susceptibility measurements, and calculations using DFT as well as multireference CASSCF methods all provide strong evidence that the electronic structure of 3 is best represented as a 5f4 U(II) metal center bound to a monoreduced arene ligand. Reactivity studies show 3 reacts as a U(I) synthon by behaving as a two-electron reductant toward I2 to form the dinuclear U(III)-U(III) triiodide species [K[2.2.2]cryptand][(UI(TDA)2)2(μ-I)] (6) and as a three-electron reductant toward cycloheptatriene (CHT) to form the U(IV) complex [K[2.2.2]cryptand][U(η7-C7H7)(TDA)2(THF)] (7). The reaction of 3 with cyclooctatetraene (COT) generates a mixture of the U(III) anion [K[2.2.2]cryptand][U(TDA)4] (1-crypt) and U(COT)2, while the addition of COT to complex 2 instead yields the dinuclear U(IV)-U(IV) inverse sandwich complex [U(TDA)3]2(μ-η8:η3-C8H8) (8). Two-electron reduction of the homoleptic Th(IV) amidate complex Th(TDA)4 (4) with KC8 gives the mono(arene) complex [K[2.2.2]cryptand][Th(TDA)3(THF)] (5). The C-C bond lengths and torsion angles in the bound arene of 5 suggest a direduced arene bound to a Th(IV) metal center; this conclusion is supported by DFT calculations.
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Affiliation(s)
- Mark D Straub
- Department of Chemistry, University of California, Berkeley, California 94720, United States.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Erik T Ouellette
- Department of Chemistry, University of California, Berkeley, California 94720, United States.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Michael A Boreen
- Department of Chemistry, University of California, Berkeley, California 94720, United States.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - R David Britt
- Department of Chemistry, University of California─Davis, Davis, California 95616, United States
| | - Khetpakorn Chakarawet
- Department of Chemistry, University of California─Davis, Davis, California 95616, United States
| | - Iskander Douair
- Université de Toulouse et CNRS, INSA, UPS, UMR 5215, LPCNO 135 Avenue de Rangueil, 31077 Toulouse, France
| | - Colin A Gould
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Laurent Maron
- Université de Toulouse et CNRS, INSA, UPS, UMR 5215, LPCNO 135 Avenue de Rangueil, 31077 Toulouse, France
| | - Iker Del Rosal
- Université de Toulouse et CNRS, INSA, UPS, UMR 5215, LPCNO 135 Avenue de Rangueil, 31077 Toulouse, France
| | - David Villarreal
- Department of Chemistry, University of California─Davis, Davis, California 95616, United States
| | - Stefan G Minasian
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - John Arnold
- Department of Chemistry, University of California, Berkeley, California 94720, United States.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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