1
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Bousrez G, Harakat D, Chevreux S, Déchamps-Olivier I, Jaroschik F. Choosing between Ti(II) and Ti(III): selective reduction of titanocene dichloride by elemental lanthanides. Dalton Trans 2024; 53:15595-15601. [PMID: 39230327 DOI: 10.1039/d4dt02004a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/05/2024]
Abstract
The reduction of titanocene dichloride Cp2TiCl2 with lanthanide metals has led to the discovery of a surprising lanthanide effect: while with most lanthanides, a divalent [Cp2Ti] equivalent was obtained, the use of samarium or ytterbium only led to the reduction to trivalent [Cp2TiCl]-type complexes, including the structurally characterized heterobimetallic complex [Cp2Ti(μ-Cl)2SmCl2(THF)3]. These results were corroborated by reactivity studies (alkyne coupling and radical reactions), EPR spectroscopy and electrospray mass spectrometry, providing new insights into the reduction chemistry of lanthanide metals.
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Affiliation(s)
- Guillaume Bousrez
- Université de Reims Champagne Ardenne, CNRS UMR 7312, ICMR, URCATech, 51100 Reims, France
- Department of Biological and Chemical Engineering, Aarhus University, 8000 Aarhus C, Denmark
| | - Dominique Harakat
- Université de Reims Champagne Ardenne, CNRS UMR 7312, ICMR, URCATech, 51100 Reims, France
| | - Sylviane Chevreux
- Université de Reims Champagne Ardenne, CNRS UMR 7312, ICMR, URCATech, 51100 Reims, France
- Institut de Recherche de Chimie Paris, UMR CNRS 8247, Chimie ParisTech, PSL University, 75005 Paris, France
| | | | - Florian Jaroschik
- Université de Reims Champagne Ardenne, CNRS UMR 7312, ICMR, URCATech, 51100 Reims, France
- ICGM, Univ. Montpellier, CNRS, ENSCM, 34090 Montpellier, France.
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2
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Wang X, He J, Wang YN, Zhao Z, Jiang K, Yang W, Zhang T, Jia S, Zhong K, Niu L, Lan Y. Strategies and Mechanisms of First-Row Transition Metal-Regulated Radical C-H Functionalization. Chem Rev 2024; 124:10192-10280. [PMID: 39115179 DOI: 10.1021/acs.chemrev.4c00188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2024]
Abstract
Radical C-H functionalization represents a useful means of streamlining synthetic routes by avoiding substrate preactivation and allowing access to target molecules in fewer steps. The first-row transition metals (Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) are Earth-abundant and can be employed to regulate radical C-H functionalization. The use of such metals is desirable because of the diverse interaction modes between first-row transition metal complexes and radical species including radical addition to the metal center, radical addition to the ligand of metal complexes, radical substitution of the metal complexes, single-electron transfer between radicals and metal complexes, hydrogen atom transfer between radicals and metal complexes, and noncovalent interaction between the radicals and metal complexes. Such interactions could improve the reactivity, diversity, and selectivity of radical transformations to allow for more challenging radical C-H functionalization reactions. This review examines the achievements in this promising area over the past decade, with a focus on the state-of-the-art while also discussing existing limitations and the enormous potential of high-value radical C-H functionalization regulated by these metals. The aim is to provide the reader with a detailed account of the strategies and mechanisms associated with such functionalization.
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Affiliation(s)
- Xinghua Wang
- College of Chemistry, and Pingyuan Laboratory, Zhengzhou University, Zhengzhou, Henan 450001, P. R. China
| | - Jing He
- College of Chemistry, and Pingyuan Laboratory, Zhengzhou University, Zhengzhou, Henan 450001, P. R. China
| | - Ya-Nan Wang
- School of Chemistry and Chemical Engineering, Chongqing Key Laboratory of Chemical Theory and Mechanism, Chongqing University, Chongqing 401331, P. R. China
| | - Zhenyan Zhao
- College of Chemistry, and Pingyuan Laboratory, Zhengzhou University, Zhengzhou, Henan 450001, P. R. China
| | - Kui Jiang
- College of Chemistry, and Pingyuan Laboratory, Zhengzhou University, Zhengzhou, Henan 450001, P. R. China
| | - Wei Yang
- College of Chemistry, and Pingyuan Laboratory, Zhengzhou University, Zhengzhou, Henan 450001, P. R. China
| | - Tao Zhang
- Institute of Intelligent Innovation, Henan Academy of Sciences, Zhengzhou, Henan 451162, P. R. China
| | - Shiqi Jia
- College of Chemistry, and Pingyuan Laboratory, Zhengzhou University, Zhengzhou, Henan 450001, P. R. China
| | - Kangbao Zhong
- State Key Laboratory of Antiviral Drugs, Pingyuan Laboratory, Henan Normal University, Xinxiang, Henan 453007, P. R. China
| | - Linbin Niu
- College of Chemistry, and Pingyuan Laboratory, Zhengzhou University, Zhengzhou, Henan 450001, P. R. China
- State Key Laboratory of Antiviral Drugs, Pingyuan Laboratory, Henan Normal University, Xinxiang, Henan 453007, P. R. China
| | - Yu Lan
- College of Chemistry, and Pingyuan Laboratory, Zhengzhou University, Zhengzhou, Henan 450001, P. R. China
- School of Chemistry and Chemical Engineering, Chongqing Key Laboratory of Chemical Theory and Mechanism, Chongqing University, Chongqing 401331, P. R. China
- State Key Laboratory of Antiviral Drugs, Pingyuan Laboratory, Henan Normal University, Xinxiang, Henan 453007, P. R. China
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3
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Álvarez-Ruiz E, Sancho I, Navarro M, Fernández I, Santamaría C, Hernán-Gómez A. A Mixed-Valence Ti(II)/Ti(III) Inverted Sandwich Compound as a Regioselective Catalyst for the Uncommon 1,3,5-Alkyne Cyclotrimerization. Inorg Chem 2024; 63:8642-8653. [PMID: 38690944 PMCID: PMC11094787 DOI: 10.1021/acs.inorgchem.4c00149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 04/19/2024] [Accepted: 04/23/2024] [Indexed: 05/03/2024]
Abstract
The synthesis, structure, and catalytic activity of a Ti(II)/Ti(III) inverted sandwich compound are presented in this study. Synthesis of the arene-bridged dititanium compound begins with the preparation of the titanium(IV) precursor [TiCl2(MesPDA)(thf)2] (MesPDA = N,N'-bis(2,4,6-trimethylphenyl)-o-phenylenediamide) (2). The reduction of 2 with sodium metal results in species [{Ti(MesPDA)(thf)}2(μ-Cl)3{Na}] (3) in oxidation state III. To achieve the lower oxidation state II, 2 undergoes reduction through alkylation with lithium cyclopentyl. This alkylation approach triggers a cascade of reactions, including β-hydride abstraction/elimination, hydrogen evolution, and chemical reduction, to generate the Ti(II)/Ti(III) compound [Li(thf)4][(TiMesPDA)2(μ-η6: η6-C6H6)] (4). X-ray and EPR characterization confirms the mixed-valence states of the titanium species. Compound 4 catalyzes a mild, efficient, and regiospecific cyclotrimerization of alkynes to form 1,3,5-substituted arenes. Kinetic data support a mechanism involving a binuclear titanium arene compound, similar to compound 4, as the resting state. The active catalyst promotes the oxidative coupling of two alkynes in the rate-limiting step, followed by a rapid [4 + 2] cycloaddition to form the arene product. Computational analysis of the resting state for the cycloaddition of trimethylsilylacetylene indicates a thermodynamic preference for stabilizing the 1,3,5-arene within the space between the two [TiMesPDA] fragments, consistent with the observed regioselectivity.
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Affiliation(s)
- Elena Álvarez-Ruiz
- Departamento
de Química Orgánica y Química Inorgánica,
Instituto de Investigación Química “Andrés
M. del Río” (IQAR), Universidad
de Alcalá, Campus Universitario, Alcalá de Henares, Madrid E-28805, Spain
| | - Ignacio Sancho
- Departamento
de Química Orgánica y Química Inorgánica,
Instituto de Investigación Química “Andrés
M. del Río” (IQAR), Universidad
de Alcalá, Campus Universitario, Alcalá de Henares, Madrid E-28805, Spain
| | - Marta Navarro
- Departamento
de Química Inorgánica, Orgánica y Bioquímica,
Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha, Ciudad Real 13071, Spain
| | - Israel Fernández
- Departamento
de Química Orgánica I, Facultad de Ciencias Químicas
and Centro de Innovación en Química Avanzada (ORFEO−CINQA), Universidad Complutense de Madrid, Madrid 28040, Spain
| | - Cristina Santamaría
- Departamento
de Química Orgánica y Química Inorgánica,
Instituto de Investigación Química “Andrés
M. del Río” (IQAR), Universidad
de Alcalá, Campus Universitario, Alcalá de Henares, Madrid E-28805, Spain
| | - Alberto Hernán-Gómez
- Departamento
de Química Orgánica y Química Inorgánica,
Instituto de Investigación Química “Andrés
M. del Río” (IQAR), Universidad
de Alcalá, Campus Universitario, Alcalá de Henares, Madrid E-28805, Spain
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4
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Morozov AG, Dodonov VA, Rychagova EA, Ketkov SY, Fedushkin IL. Ligand-Induced Intramolecular Redox Diversity in Titanium Complexes with Acenaphthene-1,2-diimine. Inorg Chem 2024; 63:4657-4668. [PMID: 38401059 DOI: 10.1021/acs.inorgchem.3c04250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2024]
Abstract
A series of the chlorido and alkoxychlorido titanium complexes of the general formula (dpp-Bian)Ti(OiPr)nCl3-n, where dpp-Bian = 1,2-bis[(2,6-iPr2C6H3)imino]acenaphthene n = 0 (2), 1 (3), 2 (4), as well as (dpp-Bian)Ti(OiPr)2 (5) and (dpp-Bian)Ti(OiPr)Cl3 (3-Cl), were isolated and characterized using single-crystal X-ray diffraction analysis and spectroscopic studies combined with density functional theory (DFT) calculations. In the solid state, compounds 2-4 reveal a square-pyramidal geometry at the metal center supported with monoanionic dpp-Bian, whereas 3-Cl with a neutral diimine ligand and 5 bearing a dianionic enebisamide dpp-Bian show, respectively, an octahedral and tetrahedral coordination surrounding the metal ion. Paramagnetic complexes 2-4 exhibit electron paramagnetic resonance spectra in both toluene solution and solid state, confirming the transfer of spin density from the metal ion to the dpp-Bian ligand as the number of alkoxy groups increases. The increase in polarity of the Ti-N bonds in the row 2 < 3 < 4 contributes to enhanced stability of the metal complexes with respect to O-donor molecules. Thus, in tetrahydrofuran (THF), compounds 2 and 3 undergo reversible solvolysis, whereas complex 4 is stable. The charge and spin density distributions as well as molecular orbital energies in 2-4 were analyzed on the basis of DFT calculations which also provided information on the electronic transition energies, absorption band assignments, and thermodynamic parameters of the reactions between the complexes and THF.
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Affiliation(s)
- Alexander G Morozov
- G. A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences (IOMC RAS), Tropinina 49, Nizhny Novgorod 603950, Russian Federation
| | - Vladimir A Dodonov
- G. A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences (IOMC RAS), Tropinina 49, Nizhny Novgorod 603950, Russian Federation
| | - Elena A Rychagova
- G. A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences (IOMC RAS), Tropinina 49, Nizhny Novgorod 603950, Russian Federation
| | - Sergey Yu Ketkov
- G. A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences (IOMC RAS), Tropinina 49, Nizhny Novgorod 603950, Russian Federation
| | - Igor L Fedushkin
- G. A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences (IOMC RAS), Tropinina 49, Nizhny Novgorod 603950, Russian Federation
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5
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Landaeta VR, Horsley Downie TM, Wolf R. Low-Valent Transition Metalate Anions in Synthesis, Small Molecule Activation, and Catalysis. Chem Rev 2024; 124:1323-1463. [PMID: 38354371 PMCID: PMC10906008 DOI: 10.1021/acs.chemrev.3c00121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 10/09/2023] [Accepted: 10/09/2023] [Indexed: 02/16/2024]
Abstract
This review surveys the synthesis and reactivity of low-oxidation state metalate anions of the d-block elements, with an emphasis on contributions reported between 2006 and 2022. Although the field has a long and rich history, the chemistry of transition metalate anions has been greatly enhanced in the last 15 years by the application of advanced concepts in complex synthesis and ligand design. In recent years, the potential of highly reactive metalate complexes in the fields of small molecule activation and homogeneous catalysis has become increasingly evident. Consequently, exciting applications in small molecule activation have been developed, including in catalytic transformations. This article intends to guide the reader through the fascinating world of low-valent transition metalates. The first part of the review describes the synthesis and reactivity of d-block metalates stabilized by an assortment of ligand frameworks, including carbonyls, isocyanides, alkenes and polyarenes, phosphines and phosphorus heterocycles, amides, and redox-active nitrogen-based ligands. Thereby, the reader will be familiarized with the impact of different ligand types on the physical and chemical properties of metalates. In addition, ion-pairing interactions and metal-metal bonding may have a dramatic influence on metalate structures and reactivities. The complex ramifications of these effects are examined in a separate section. The second part of the review is devoted to the reactivity of the metalates toward small inorganic molecules such as H2, N2, CO, CO2, P4 and related species. It is shown that the use of highly electron-rich and reactive metalates in small molecule activation translates into impressive catalytic properties in the hydrogenation of organic molecules and the reduction of N2, CO, and CO2. The results discussed in this review illustrate that the potential of transition metalate anions is increasingly being tapped for challenging catalytic processes with relevance to organic synthesis and energy conversion. Therefore, it is hoped that this review will serve as a useful resource to inspire further developments in this dynamic research field.
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Affiliation(s)
| | | | - Robert Wolf
- University of Regensburg, Institute
of Inorganic Chemistry, 93040 Regensburg, Germany
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6
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Oloyede UN, Flowers RA. Coordination-induced bond weakening and small molecule activation by low-valent titanium complexes. Dalton Trans 2024; 53:2413-2441. [PMID: 38224159 DOI: 10.1039/d3dt03454b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2024]
Abstract
Bond activation of small molecules through coordination to low valent metal complexes in M⋯X-H type interactions (where X = O, N, B, Si, etc.) leads to the formation of unusually weak X-H bonds and provides a powerful approach for the synthesis of target compounds under very mild conditions. Coordination of small molecules like water, amides, silanes, boranes, and dinitrogen to Ti(III) or Ti(II) complexes results in the synergetic redistribution of electrons between the metal orbitals and the ligand orbitals which weakens and enables the facile cleavage of the X-H or N-N bonds of the ligands. This review presents an overview of coordination-induced bond activation of small molecules by low valent titanium complexes. In particular, the applications of low valent titanium-induced bond weakening in nitrogen fixation are presented. The review concludes with potential future directions for work in this area including low-valent Ti-based PCET systems, photocatalytic nitrogen reduction, and approaches to tailoring complexes for optimal bond activation.
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Affiliation(s)
| | - Robert A Flowers
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
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7
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Sancho I, Navarro M, Montilla M, Salvador P, Santamaría C, Luis JM, Hernán-Gómez A. Ti(III) Catalysts for CO 2/Epoxide Copolymerization at Unusual Ambient Pressure Conditions. Inorg Chem 2023; 62:14873-14887. [PMID: 37651747 PMCID: PMC10521022 DOI: 10.1021/acs.inorgchem.3c01249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Indexed: 09/02/2023]
Abstract
Titanium compounds in low oxidation states are highly reducing species and hence powerful tools for the functionalization of small molecules. However, their potential has not yet been fully realized because harnessing these highly reactive complexes for productive reactivity is generally challenging. Advancing this field, herein we provide a detailed route for the formation of titanium(III) orthophenylendiamido (PDA) species using [LiBHEt3] as a reducing agent. Initially, the corresponding lithium PDA compounds [Li2(ArPDA)(thf)3] (Ar = 2,4,6-trimethylphenyl (MesPDA), 2,6-diisopropylphenyl (iPrPDA)) are combined with [TiCl4(thf)2] to form the heterobimetallic complexes [{TiCl(ArPDA)}(μ-ArPDA){Li(thf)n}] (n = 1, Ar = iPr 3 and n = 2, Ar = Mes 4). Compound 4 evolves to species [Ti(MesPDA)2] (6) via thermal treatment. In contrast, the transformation of 3 into [Ti(iPrPDA)2] (5) only occurs in the presence of [LiNMe2], through a lithium-assisted process, as revealed by density functional theory (DFT). Finally, the Ti(IV) compounds 3-6 react with [LiBHEt3] to give rise to the Ti(III) species [Li(thf)4][Ti(ArPDA)2] (Ar = iPr 8, Mes 9). These low-valent compounds in combination with [PPN]Cl (PPN = bis(triphenylphosphine)iminium) are proved to be highly selective catalysts for the copolymerization of CO2 and cyclohexene epoxide. Reactions occur at 1 bar pressure with activity/selectivity levels similar to Salen-Cr(III) compounds.
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Affiliation(s)
- Ignacio Sancho
- Departamento
de Química Orgánica y Química Inorgánica,
Instituto de Investigación Química “Andrés
M. del Río” (IQAR), Universidad
de Alcalá, Campus
Universitario, E-28805 Alcalá de Henares, Madrid, Spain
| | - Marta Navarro
- Departamento
de Química Orgánica y Química Inorgánica,
Instituto de Investigación Química “Andrés
M. del Río” (IQAR), Universidad
de Alcalá, Campus
Universitario, E-28805 Alcalá de Henares, Madrid, Spain
| | - Marc Montilla
- Institute
of Computational Chemistry and Catalysis and Department of Chemistry, University of Girona, Campus de Montilivi, 17003 Girona, Catalonia, Spain
| | - Pedro Salvador
- Institute
of Computational Chemistry and Catalysis and Department of Chemistry, University of Girona, Campus de Montilivi, 17003 Girona, Catalonia, Spain
| | - Cristina Santamaría
- Departamento
de Química Orgánica y Química Inorgánica,
Instituto de Investigación Química “Andrés
M. del Río” (IQAR), Universidad
de Alcalá, Campus
Universitario, E-28805 Alcalá de Henares, Madrid, Spain
| | - Josep M. Luis
- Institute
of Computational Chemistry and Catalysis and Department of Chemistry, University of Girona, Campus de Montilivi, 17003 Girona, Catalonia, Spain
| | - Alberto Hernán-Gómez
- Departamento
de Química Orgánica y Química Inorgánica,
Instituto de Investigación Química “Andrés
M. del Río” (IQAR), Universidad
de Alcalá, Campus
Universitario, E-28805 Alcalá de Henares, Madrid, Spain
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8
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Beh DW, Cuellar De Lucio AJ, del Rosal I, Maron L, Spasyuk D, Gelfand BS, Li JB, Piers WE. Organotitanium Complexes Supported by a Dianionic Pentadentate Ligand. Organometallics 2023. [DOI: 10.1021/acs.organomet.2c00609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
Affiliation(s)
- Daniel W. Beh
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | | | - Iker del Rosal
- LPCNO, Université de Toulouse, INSA, UPS, LPCNO, 135 avenue de Rangueil, F-31077 Toulouse, France
- CNRS, LPCNO, F-31077 Toulouse, France
| | - Laurent Maron
- LPCNO, Université de Toulouse, INSA, UPS, LPCNO, 135 avenue de Rangueil, F-31077 Toulouse, France
- CNRS, LPCNO, F-31077 Toulouse, France
| | - Denis Spasyuk
- Canadian Light Source Inc., 44 Innovation Boulevard, Saskatoon, Saskatchewan S7N 2V3, Canada
| | - Benjamin S. Gelfand
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Jian-Bin Li
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Warren E. Piers
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
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9
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Calvo-Molina A, del Horno E, Jover J, Pérez-Redondo A, Yélamos C, Zapata R. Monocyclopentadienyltitanium(III) Complexes with Hydridoborato Ligands. Organometallics 2023. [DOI: 10.1021/acs.organomet.2c00580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Affiliation(s)
- Adrián Calvo-Molina
- Departamento de Química Orgánica y Química Inorgánica, Instituto de Investigación Química “Andrés M. del Río” (IQAR), Universidad de Alcalá, 28805 Alcalá de Henares, Madrid, Spain
| | - Estefanía del Horno
- Departamento de Química Orgánica y Química Inorgánica, Instituto de Investigación Química “Andrés M. del Río” (IQAR), Universidad de Alcalá, 28805 Alcalá de Henares, Madrid, Spain
| | - Jesús Jover
- Secció de Química Inorgànica, Departament de Química Inorgànica i Orgànica, Institut de Química Teòrica i Computacional (IQTC-UB), Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain
| | - Adrián Pérez-Redondo
- Departamento de Química Orgánica y Química Inorgánica, Instituto de Investigación Química “Andrés M. del Río” (IQAR), Universidad de Alcalá, 28805 Alcalá de Henares, Madrid, Spain
| | - Carlos Yélamos
- Departamento de Química Orgánica y Química Inorgánica, Instituto de Investigación Química “Andrés M. del Río” (IQAR), Universidad de Alcalá, 28805 Alcalá de Henares, Madrid, Spain
| | - Rosa Zapata
- Departamento de Química Orgánica y Química Inorgánica, Instituto de Investigación Química “Andrés M. del Río” (IQAR), Universidad de Alcalá, 28805 Alcalá de Henares, Madrid, Spain
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10
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Huh DN, Koby RF, Stuart ZE, Dunscomb RJ, Schley ND, Tonks IA. Reassessment of N 2 activation by low-valent Ti-amide complexes: a remarkable side-on bridged bis-N 2 adduct is actually an arene adduct. Chem Sci 2022; 13:13330-13337. [PMID: 36507167 PMCID: PMC9682900 DOI: 10.1039/d2sc04368h] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 10/13/2022] [Indexed: 12/15/2022] Open
Abstract
The complex {(TMEDA)2Li}{[Ti(N(TMS)2)2]2(μ-η2:η2-N2)2} (5-Li) is the only transition metal N2 complex ever reported with two side-on N2 adducts. In this report, the similarity of 5-Li to a new inverse sandwich toluene adduct {(PhMe)K}{[Ti(N(TMS)2)2]2(μ-PhMe)} (6-K) necessitated a re-examination of the structure of 5-Li. Through a reassessment of the original disordered crystal data of 5-Li and new independent syntheses brought about through revisitation of the original reaction conditions, 5-Li has been re-assigned as an inverse sandwich toluene adduct, {(TMEDA)2Li}{[Ti(N(TMS)2)2]2(μ-PhMe)} (6-Li). The original crystal data could be fitted almost equally well to structural solutions as either 5-Li or 6-Li, and this study highlights the importance of a holistic examination of modeled data and the need for secondary/complementary analytical methods in paramagnetic inorganic syntheses, especially when presenting unique and unexpected results. In addition, further examination of reduction reactions of Ti[N(TMS)2]3 and [(TMS)2N]2TiCl(THF) in the presence of KC8 revealed rich solvent- and counterion-dependent chemistry, including several degrees of N2 activation (bridging nitride complexes, terminal bridging N2 complexes) as well as ligand C-H activation.
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Affiliation(s)
- Daniel N Huh
- Department of Chemistry, University of Minnesota - Twin Cities Minneapolis MN 55455 USA
| | - Ross F Koby
- Department of Chemistry, University of Minnesota - Twin Cities Minneapolis MN 55455 USA
| | - Zoe E Stuart
- Department of Chemistry, University of Minnesota - Twin Cities Minneapolis MN 55455 USA
| | - Rachel J Dunscomb
- Department of Chemistry, University of Minnesota - Twin Cities Minneapolis MN 55455 USA
| | - Nathan D Schley
- Department of Chemistry, Vanderbilt University Nashville TN 37235 USA
| | - Ian A Tonks
- Department of Chemistry, University of Minnesota - Twin Cities Minneapolis MN 55455 USA
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11
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Gómez-Torres A, Mavragani N, Metta-Magaña A, Murugesu M, Fortier S. Molecular Capacitors: Accessible 6- and 8-Electron Redox Chemistry from Dimeric "Ti(I)" and "Ti(0)" Synthons Supported by Imidazolin-2-Iminato Ligands. Inorg Chem 2022; 61:16856-16873. [PMID: 36219252 DOI: 10.1021/acs.inorgchem.2c02881] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Reduction of the diamagnetic Ti(III)/Ti(III) dimer [Cl2Ti(μ-NImDipp)]2 (1) (NImDipp = [1,3-bis(Dipp)imidazolin-2-iminato]-, Dipp = C6H3-2,6-iPr2) with 4 and 6 equiv of KC8 generates the intramolecularly arene-masked, dinuclear titanium compounds [(μ-N-η6-ImDipp)Ti]2 (2) and {[(Et2O)2K](μ-N-μ-η6:η6-ImDipp)Ti}2 (3), respectively, in modest yields. The compounds have been structurally characterized by X-ray crystallographic analysis, and inspection of the bond metrics within the η6-coordinated aryl substituent of the bridging imidazolin-2-iminato ligand shows perturbation of the aromatic system most consistent with two-electron reduction of the ring. As such, 2 and 3 can be assigned respectively as possessing metal centers in formal Ti(III)/Ti(III) and Ti(II)/Ti(II) oxidation states. Exploration of their redox chemistry reveal the ability to reduce several substrate equivalents. For instance, treatment of 2 with excess C8H8 (COT) forms the novel COT-bridged complex [(ImDippN)(η8-COT)Ti](μ-η2:η3-COT)[Ti(η4-COT)(NImDipp)] (4) that dissociates in THF solutions to give mononuclear (ImDippN)Ti(η8-COT)(THF) (5). Addition of COT to 3 yields heterometallic [(ImDippN)(η4-COT)Ti(μ-η4:η5-COT)K(THF)(μ-η6:η4-COT)Ti(NImDipp)(μ-η4:η4-COT)K(THF)2]n (6). Compounds 4 and 5 are the products of the 4-electron oxidation of 2, while 6 stands as the 8-electron oxidation product of 3. Reduction of organozides was also explored. Low temperature reaction of 2 with 4 equiv of AdN3 gives the terminal and bridged imido complex [(ImDippN)Ti(═NAd)](μ-NAd)2[Ti(NImDipp)(N3Ad)] (7) that undergoes intermolecular C-H activation of toluene at room temperature to afford the amido compound [(ImDippN)Ti(NHAd)](μ-NAd)2[Ti(C6H4Me)(NImDipp)] (8-tol). These complexes are the 6-electron oxidation products of the reaction of 2 with AdN3. Furthermore, treatment of 3 with 4 equiv of AdN3 produces the thermally stable Ti(III)/Ti(III) terminal and bridged imido [K(18-crown-6)(THF)2]{[(ImDippN)Ti(NAd)](μ-NAd)2K[Ti(NImDipp)]} (10). Altogether, these reactions firmly establish 2 and 3 as unprecedented Ti(I)/Ti(I) and Ti(0)/Ti(0) synthons with the clear capacity to effect multielectron reductions ranging from 4 to 8 electrons.
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Affiliation(s)
- Alejandra Gómez-Torres
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
| | - Niki Mavragani
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Alejandro Metta-Magaña
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
| | - Muralee Murugesu
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Skye Fortier
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
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12
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Cuellar De Lucio AJ, Cai IC, Witzke RJ, Desnoyer AN, Tilley TD. Synthesis, Characterization, and Reactivity of Low-Coordinate Titanium(III) Amido Complexes. Organometallics 2022. [DOI: 10.1021/acs.organomet.2c00162] [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)
| | - Irene C. Cai
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720-1460, United States
| | - Ryan J. Witzke
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720-1460, United States
| | - Addison N. Desnoyer
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720-1460, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - T. Don Tilley
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720-1460, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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13
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Abstract
In molecular photochemistry, charge-transfer emission is well understood and widely exploited. In contrast, luminescent metal-centered transitions only came into focus in recent years. This gave rise to strongly phosphorescent CrIII complexes with a d3 electronic configuration featuring luminescent metal-centered excited states which are characterized by the flip of a single spin. These so-called spin-flip emitters possess unique properties and require different design strategies than traditional charge-transfer phosphors. In this review, we give a brief introduction to ligand field theory as a framework to understand this phenomenon and outline prerequisites for efficient spin-flip emission including ligand field strength, symmetry, intersystem crossing and common deactivation pathways using CrIII complexes as instructive examples. The recent progress and associated challenges of tuning the energies of emissive excited states and of emerging applications of the unique photophysical properties of spin-flip emitters are discussed. Finally, we summarize the current state-of-the-art and challenges of spin-flip emitters beyond CrIII with d2, d3, d4 and d8 electronic configuration, where we mainly cover pseudooctahedral molecular complexes of V, Mo, W, Mn, Re and Ni, and highlight possible future research opportunities.
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14
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de Graaff S, Schwitalla K, Haaker CV, Bengen N, Schmidtmann M, Beckhaus R. A Niobium Pentafulvene Ethylene Complex: Synthesis, Properties and Reaction Pathways. Dalton Trans 2022; 51:12502-12511. [DOI: 10.1039/d2dt02063g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The π-η5:σ-η1 coordination mode of early transition metal pentafulvene ligands yields a strongly nucleophilic exocyclic carbon atom (Cexo). The substitution of the chlorido ligand of bis(η5:η1-(di-p-tolyl)pentafulvene)niobium chloride (1) by reaction...
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Rosenthal U. Latest News: Reactions of Group 4 Bis(trimethylsilyl)acetylene Metallocene Complexes and Applications of the Obtained Products. ChemistryOpen 2021; 10:1234-1243. [PMID: 34882978 PMCID: PMC8659550 DOI: 10.1002/open.202100258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 11/23/2021] [Indexed: 11/16/2022] Open
Abstract
Recently published reactions of group 4 metallocene bis(trimethylsilyl)acetylene (btmsa) complexes from the last two years are reviewed. Complexes like Cp'2 Ti(η2 -Me3 SiC2 SiMe3 ) and Cp2 Zr(py)(η2 -Me3 SiC2 SiMe3 ) with Cp' as Cp (cyclopentadienyl) and Cp* (pentamethylcyclopentadienyl) have been considered (py=pyridine). These complexes can liberate a reactive low-valent titanium or zirconium center by dissociation of the ligands and act as ''masked'' MII complexes (M=Ti, Zr). They represent excellent sources for the clean generation of the reactive coordinatively and electronically unsaturated complex fragments [Cp'2 M]. This is the reason why they were used for many synthetic and catalytic reactions during the last years. As an update to several review articles on this topic, this contribution provides an update with recent examples of preparative organometallic and organic chemistry of these complexes, acting as reagents for a wide range of coordinating and coupling reactions. In addition, applications and investigations concerning reaction products derived from this chemistry are mentioned, too.
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Affiliation(s)
- Uwe Rosenthal
- Leibniz Institute for Catalysis at theUniversity of RostockAlbert-Einstein-Str. 29 A18059RostockGermany
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