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Hales DP, Rajeshkumar T, Shiau AA, Rao G, Ouellette ET, Bergman RG, Britt RD, Maron L, Arnold J. Panoply of P: An Array of Rhenium-Phosphorus Complexes Generated from a Transition Metal Anion. Inorg Chem 2024; 63:11296-11310. [PMID: 38836624 DOI: 10.1021/acs.inorgchem.4c01085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Abstract
We expand upon the synthetic utility of anionic rhenium complex Na[(BDI)ReCp] (1, BDI = N,N'-bis(2,6-diisopropylphenyl)-3,5-dimethyl-β-diketiminate) to generate several rhenium-phosphorus complexes. Complex 1 reacts in a metathetical manner with chlorophosphines Ph2PCl, MeNHP-Cl, and OHP-Cl to generate XL-type phosphido complexes 2, 3, and 4, respectively (MeNHP-Cl = 2-chloro-1,3-dimethyl-1,3,2-diazaphospholidine; OHP-Cl = 2-chloro-1,3,2-dioxaphospholane). Crystallographic and computational investigations of phosphido triad 2, 3, and 4 reveal that increasing the electronegativity of the phosphorus substituent (C < N < O) results in a shortening and strengthening of the rhenium-phosphorus bond. Complex 1 reacts with iminophosphane Mes*NPCl (Mes* = 2,4,6-tritert-butylphenyl) to generate linear iminophosphanyl complex 5. In the presence of a suitable halide abstraction reagent, 1 reacts with the dichlorophosphine iPr2NPCl2 to afford cationic phosphinidene complex 6+. Complex 6+ may be reduced by one electron to form 6•, a rare example of a stable, paramagnetic phosphinidene complex. Spectroscopic and structural investigations, as well as computational analyses, are employed to elucidate the influence of the phosphorus substituent on the nature of the rhenium-phosphorus bond in 2 through 6. Furthermore, we examine several common analogies employed to understand metal phosphido, phosphinidene, and iminophosphanyl complexes.
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Affiliation(s)
- David P Hales
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Thayalan Rajeshkumar
- LPCNO, INSA Toulouse, Université de Toulouse, 135 Avenue de Rangueil, Toulouse 31077, France
| | - Angela A Shiau
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Guodong Rao
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Erik T Ouellette
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Robert G Bergman
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - R David Britt
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Laurent Maron
- LPCNO, INSA Toulouse, Université de Toulouse, 135 Avenue de Rangueil, Toulouse 31077, France
| | - John Arnold
- Department of Chemistry, University of California, Berkeley, California 94720, United States
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Ouellette ET, Magdalenski JS, Bergman RG, Arnold J. Heterobimetallic-Mediated Dinitrogen Functionalization: N-C Bond Formation at Rhenium-Group 9 Diazenido Complexes. Inorg Chem 2022; 61:16064-16071. [PMID: 36150135 DOI: 10.1021/acs.inorgchem.2c02463] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the synthesis and characterization of rhenium-group 9 heterobimetallic diazenido species (η5-Cp)Re(μ-BDI)(μ-N2)M(η4-COD) (1-M, M = Ir or Rh, Cp = cyclopentadienide, BDI = N,N'-bis(2,6-diisopropylphenyl)-3,5-dimethyl-β-diketiminate, COD = 1,5-cyclooctadiene), formed from salt elimination reactions between Na[(η5-Cp)Re(BDI)] and [MCl(η4-COD)]2. Additionally, we find that these same reagents react under an argon atmosphere to instead produce bridging hydride complexes (BDI)Re(μ-η5:η1-C5H4)(μ-H)M(η4-COD) (2-M), which undergo rearrangements upon protonation to form the alternative bridging hydrides [(η5-Cp)Re(μ-BDI)(μ-H)M(η4-COD)][(B(m-C6H3(CF3)2)4)] (3-M). Further, we demonstrate the first example of N-C bond formation at a heterobimetallic dinitrogen complex through reactions of 1-M and methyl triflate, which produces the alkylated species [(η5-Cp)Re(μ-N(Me)N)(μ-BDI)M(η4-COD)][OTf] (4-M, OTf = trifluoromethanesulfonate). A combination of spectroscopic studies, X-ray structural analysis, and computational investigations is discussed as an aid to understanding the modes of dinitrogen activation within these unique heterobimetallic complexes.
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Affiliation(s)
- 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
| | - Julian S Magdalenski
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Robert G Bergman
- Department of Chemistry, University of California, 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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van Alten RS, Wieser PA, Finger M, Abbenseth J, Demeshko S, Würtele C, Siewert I, Schneider S. Halide Effects in Reductive Splitting of Dinitrogen with Rhenium Pincer Complexes. Inorg Chem 2022; 61:11581-11591. [PMID: 35861586 DOI: 10.1021/acs.inorgchem.2c00973] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Transition metal halide complexes are used as precursors for reductive N2 activation up to full splitting into nitride complexes. Distinct halide effects on the redox properties and yields are frequently observed yet not well understood. Here, an electrochemical and computational examination of reductive N2 splitting with the rhenium(III) complexes [ReX2(PNP)] (PNP = N(CH2CH2PtBu2)2 and X = Cl, Br, I) is presented. As previously reported for the chloride precursor ( J. Am. Chem. Soc. 2018, 140, 7922), the heavier halides give rhenium(V) nitrides upon (electro-)chemical reduction in good yields yet with significantly anodically shifted electrolysis potentials along the halide series. Dinuclear, end-on N2-bridged complexes, [{ReX(PNP)}2(μ-N2)], were identified as key intermediates in all cases. However, while the chloride complex is exclusively formed via 2-electron reduction and ReIII/ReI comproportionation, the iodide system also reacts via an alternative ReII/ReII-dimerization mechanism at less negative potentials. This alternative pathway relies on the absence of the potential inversion after reduction and N2 activation that was observed for the chloride precursor. Computational analysis of the relevant ReIII/II and ReII/I redox couples by energy decomposition analysis attributes the halide-induced trends of the potentials to the dominating electrostatic Re-X bonding interactions over contributions from charge transfer.
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Affiliation(s)
- Richt S van Alten
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany
| | - Philipp A Wieser
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany
| | - Markus Finger
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany
| | - Josh Abbenseth
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany
| | - Serhiy Demeshko
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany
| | - Christian Würtele
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany
| | - Inke Siewert
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany.,International Center for Advanced Studies of Energy Conversion, University of Göttingen, 37077 Göttingen, Germany
| | - Sven Schneider
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany.,International Center for Advanced Studies of Energy Conversion, University of Göttingen, 37077 Göttingen, Germany
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Ouellette ET, Magdalenski JS, Bergman RG, Arnold J. Applications of Low-Valent Transition Metalates: Development of a Reactive Noncarbonyl Rhenium(I) Anion. Acc Chem Res 2022; 55:783-793. [PMID: 35171568 DOI: 10.1021/acs.accounts.2c00013] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Low-valent transition metalates─anionic, electronic-rich organometallic complexes─comprise a class of highly reactive chemical reagents that find integral applications in organic synthesis, small-molecule activation, transient species stabilization, and M-E bond formation, among others. The inherent reactivity of such electron-rich metal centers has necessitated the widespread use of strong backbonding ligands, particularly carbonyls, to aid in the isolation and handling of metalate reagents, albeit sometimes at the expense of partially masking their full reactivity. However, recent synthetic explorations into transition-metalate complexes devoid of archetypic back-bonding ligands have led to the discovery of highly reactive metalates capable of performing a variety of novel chemical transformations.Building on our group's long-standing interest in reactive organometallic species, a series of rational progressions in early-to-middle transition-metal chemistry ultimately led to our isolation of a rhenium(I) β-diketiminate cyclopentadienide metalate that displays exceptional reactivity. We have found this Re(I) metalate to be capable of small-molecule activation; notably, the complex reversibly binds dinitrogen in solution and can be utilized to trap N2 for the synthesis of functionalized diazenido species. By employing isolobal analogues to N2 (CO and RNC), we were able to thoroughly monitor the mechanism of activation and conclude that the metalate's sodium counterion plays an integral role in promoting dinitrogen activation through a novel side-on interaction. The Re(I) metalate is also used in forming a variety of M-E bonds, including a series of uncommon rhenium-tetrylene (Si, Ge, and Sn) complexes that display varying degrees of multiple bonding. These metal tetrylenes act to highlight deviations in chemical properties within the group 14 elements. Our metalate's utility also applies to metal-metal bond formation, as demonstrated through the synthesis of a heterotetrametallic rhenium-zinc dimer. In this reaction, the Re(I) metalate performs a dual role as a reductant and metalloligand to stabilize a transient Zn22+ core fragment. Finally, the metalate displays unique reactivity with uranium(III) to yield the first transition metal-actinide inverse-sandwich bonds, in this case with three rhenium fragments bound through their Cp moieties surrounding the uranium center. Notably, throughout these endeavors we demonstrate that the metalate displays reactivity at multiple locations, including directly at the rhenium metal center, at a Cp carbon, through a Cp-sandwich mode, or through reversibly bound dinitrogen.Overall, the rhenium(I) metalate described herein demonstrates utility in diverse applications: small-molecule activation, the stabilization of reduced and/or unstable species, and the formation of unconventional M-E/M-M bonds or heterometallic complexes. Moving forward, we suggest that the continued discovery of noncarbonyl, electron-rich transition-metal anions featuring new or unconventional ligands should produce additional reactive organometallic species capable of stabilizing unique structural motifs and performing novel and unusual chemical transformations.
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Affiliation(s)
- 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
| | - Julian S. Magdalenski
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Robert G. Bergman
- Department of Chemistry, University of California, 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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