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Jazani AM, Schild DJ, Sobieski J, Hu X, Matyjaszewski K. Visible Light-ATRP Driven by Tris(2-Pyridylmethyl)Amine (TPMA) Impurities in the Open Air. Macromol Rapid Commun 2023; 44:e2200855. [PMID: 36471106 DOI: 10.1002/marc.202200855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 11/29/2022] [Indexed: 12/12/2022]
Abstract
Atom transfer radical polymerization (ATRP) of oligo(ethylene oxide) monomethyl ether methacrylate (OEOMA500 ) in water is enabled using CuBr2 with tris(2-pyridylmethyl)amine (TPMA) as a ligand under blue or green-light irradiation without requiring any additional reagent, such as a photo-reductant, or the need for prior deoxygenation. Polymers with low dispersity (Đ = 1.18-1.25) are synthesized at high conversion (>95%) using TPMA from three different suppliers, while no polymerization occurred with TPMA is synthesized and purified in the laboratory. Based on spectroscopic studies, it is proposed that TPMA impurities (i.e., imine and nitrone dipyridine), which absorb blue and green light, can act as photosensitive co-catalyst(s) in a light region where neither pure TPMA nor [(TPMA)CuBr]+ absorbs light.
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Affiliation(s)
- Arman Moini Jazani
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
| | - Dirk J Schild
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
| | - Julian Sobieski
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
| | - Xiaolei Hu
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
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Panetti GB, Carroll PJ, Gau MR, Manor BC, Schelter EJ, Walsh PJ. Synthesis of an elusive, stable 2-azaallyl radical guided by electrochemical and reactivity studies of 2-azaallyl anions. Chem Sci 2021; 12:4405-4410. [PMID: 34163704 PMCID: PMC8179533 DOI: 10.1039/d0sc04822d] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 02/01/2021] [Indexed: 12/31/2022] Open
Abstract
The super electron donor (SED) ability of 2-azaallyl anions has recently been discovered and applied to diverse reactivity, including transition metal-free cross-coupling and dehydrogenative cross-coupling processes. Surprisingly, the redox properties of 2-azaallyl anions and radicals have been rarely studied. Understanding the chemistry of elusive species is the key to further development. Electrochemical analysis of phenyl substituted 2-azaallyl anions revealed an oxidation wave at E 1/2 or E pa = -1.6 V versus Fc/Fc+, which is ∼800 mV less than the reduction potential predicted (E pa = -2.4 V vs. Fc/Fc+) based on reactivity studies. Investigation of the kinetics of electron transfer revealed reorganization energies an order of magnitude lower than commonly employed SEDs. The electrochemical study enabled the synthetic design of the first stable, acyclic 2-azaallyl radical. These results indicate that the reorganization energy should be an important design consideration for the development of more potent organic reductants.
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Affiliation(s)
- Grace B Panetti
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia PA USA
| | - Patrick J Carroll
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia PA USA
| | - Michael R Gau
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia PA USA
| | - Brian C Manor
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia PA USA
| | - Eric J Schelter
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia PA USA
| | - Patrick J Walsh
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia PA USA
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Braun JD, Lozada IB, Herbert DE. In Pursuit of Panchromatic Absorption in Metal Coordination Complexes: Experimental Delineation of the HOMO Inversion Model Using Pseudo-Octahedral Complexes of Diarylamido Ligands. Inorg Chem 2020; 59:17746-17757. [PMID: 33225695 DOI: 10.1021/acs.inorgchem.0c02973] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The ability of a compound to broadly absorb light across the incident solar spectrum is an important design target in the development of molecular photosensitizers. The 'HOMO inversion' model predicts that for [(tpy)2Fe]2+ (tpy = 2,2':6',2″-terpyridine) compounds, adjusting the character of the highest occupied molecular orbital (HOMO) from metal-centered to ligand-centered can drastically improve photophysical properties by broadening absorption in the visible and increasing molar extinction coefficients. In an effort to experimentally realize strong, panchromatic absorption, a tridentate N^N-^N diarylamido ligand bearing flanking benzannulated N-heterocyclic donors (tBuL) was used to prepare deeply colored, pseudo-octahedral coordination complexes of a range of first-row transition and main-group metals [(tBuL)2M0/+; M = Fe, Co, Ni, Zn, Ga]. While the Fe(II) congener exhibits the sought-after broad absorption, isostructural and isoelectronic complexes of other first-row transition and main-group metals show vastly different absorption and redox properties. Density functional theory (DFT) calculations point toward the relative energies of the metal d orbitals and ligand orbitals as the source of major changes in electronic structure, confirming aspects and limitations of the predictive 'HOMO inversion' model in experimentally realized systems with implications for the design of abundant transition-metal sensitizers with broad, panchromatic absorptive properties.
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Affiliation(s)
- Jason D Braun
- Department of Chemistry and the Manitoba Institute of Materials, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba R3T 2N2, Canada
| | - Issiah B Lozada
- Department of Chemistry and the Manitoba Institute of Materials, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba R3T 2N2, Canada
| | - David E Herbert
- Department of Chemistry and the Manitoba Institute of Materials, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba R3T 2N2, Canada
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5
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Heins SP, Zhang B, MacMillan SN, Cundari TR, Wolczanski PT. Oxidative Additions to Ti(IV) in [(dadi)4–]TiIV(THF) Involve Carbon–Carbon Bond Formation and Redox-Noninnocent Behavior. Organometallics 2019. [DOI: 10.1021/acs.organomet.8b00930] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Spencer P. Heins
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Bufan Zhang
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Samantha N. MacMillan
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Thomas R. Cundari
- Department of Chemistry, CASCaM, University of North Texas, Denton, Texas 76201, United States
| | - Peter T. Wolczanski
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
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Pryjomska-Ray I, Zornik D, Pätzel M, Krause KB, Grubert L, Braun-Cula B, Hecht S, Limberg C. Comparing Isomeric Tridentate Carbazole-Based Click Ligands: Metal Complexes and Redox Chemistry. Chemistry 2018; 24:5341-5349. [PMID: 29265510 DOI: 10.1002/chem.201704858] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Indexed: 11/11/2022]
Abstract
Two novel bis(triazolyl)carbazole ligands Hbtc1 (3,6-di(tert-butyl)-1,8-bis[(1-(3,5-di(tert-butyl)phenyl)-1,2,3-triazol-4-yl)]-9H-carbazole) and Hbtc2 (3,6-di(tert-butyl)-1,8-bis[(4-(3,5-di(tert-butyl)phenyl)-1,2,3-triazol-1-yl)]-9H-carbazole), differing in the regiochemistry of triazole attachment, have been synthesized by Cu-catalyzed azide-alkyne cycloaddition, the so-called "click-reactions". Metalation with Ru, Zn, and Ni precursors led to the formation of M(btc)2 complexes (M=Ru, Zn, Ni), with two deprotonated ligands coordinating to the metal center in tridentate fashion, forming almost perfectly octahedral coordination spheres. The redox properties of M(btc)2 complexes have been investigated by cyclic voltammetry, UV/Vis spectroscopy, spectroelectrochemistry, and chemically. The CV of the ruthenium complexes revealed three quasi-reversible one-electron oxidation processes, one assigned as the RuII/III couple and two originating from ligand-based oxidations. The CVs of both Zn and Ni complexes contained only two oxidation waves corresponding to the oxidation of the two ligands. The oxidation potentials of complexes derived from Hbtc1 ligands were found to be 300-400 mV lower than those of the corresponding complexes derived from Hbtc2, reflecting the significant difference in donation through the N(2) or N(3) atom of the triazole moiety.
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Affiliation(s)
- Iweta Pryjomska-Ray
- Department of Chemistry and IRIS Adlershof, Humboldt Universität zu Berlin, Brook-Taylor-Strasse 2, 12489, Berlin, Germany
| | - Denise Zornik
- Department of Chemistry and IRIS Adlershof, Humboldt Universität zu Berlin, Brook-Taylor-Strasse 2, 12489, Berlin, Germany
| | - Michael Pätzel
- Department of Chemistry and IRIS Adlershof, Humboldt Universität zu Berlin, Brook-Taylor-Strasse 2, 12489, Berlin, Germany
| | - Konstantin B Krause
- Department of Chemistry and IRIS Adlershof, Humboldt Universität zu Berlin, Brook-Taylor-Strasse 2, 12489, Berlin, Germany
| | - Lutz Grubert
- Department of Chemistry and IRIS Adlershof, Humboldt Universität zu Berlin, Brook-Taylor-Strasse 2, 12489, Berlin, Germany
| | - Beatrice Braun-Cula
- Department of Chemistry and IRIS Adlershof, Humboldt Universität zu Berlin, Brook-Taylor-Strasse 2, 12489, Berlin, Germany
| | - Stefan Hecht
- Department of Chemistry and IRIS Adlershof, Humboldt Universität zu Berlin, Brook-Taylor-Strasse 2, 12489, Berlin, Germany
| | - Christian Limberg
- Department of Chemistry and IRIS Adlershof, Humboldt Universität zu Berlin, Brook-Taylor-Strasse 2, 12489, Berlin, Germany
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8
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Barbour JC, Kim AJI, deVries E, Shaner SE, Lovaasen BM. Chromium(III) Bis-Arylterpyridyl Complexes with Enhanced Visible Absorption via Incorporation of Intraligand Charge-Transfer Transitions. Inorg Chem 2017; 56:8212-8222. [PMID: 28665604 DOI: 10.1021/acs.inorgchem.7b00953] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A series of chromium(III) bis-arylterpyridyl complexes containing intraligand charge-transfer (ILCT) excited states were prepared and characterized. These complexes show significant absorption in the visible region due to the ILCT bands. The ILCT bands are tunable across the UV and visible spectrum via incorporation of electron-withdrawing and electron-donating groups on the aryl ring. The absorption of Cr(4'-(4-methoxyphenyl)-2,2':6',2″-terpyridine)23+ (4) in particular is much stronger in the visible region (ε = 11 900 M-1 cm-1 at 450 nm and ε = 5090 M-1 cm-1 at 500 nm) than that of the parent complex Cr(tpy)23+ (tpy = 2,2':6',2″-terpyridine; ε = 2160 M-1 cm-1 at 450 nm, and ε = 170 M-1 cm-1 at 500 nm). Emission experiments on this series reveal Cr(III)-based phosphorescence with lifetimes from 140 to 600 ns upon excitation into the ILCT bands, which indicates funneling of the excitation energy from ligand-localized excited states to Cr(III)-based excited states. Cyclic voltammograms exhibit at least three reversible ligand-based reductions. The first reduction shows shifts of up to -160 mV compared to Cr(tpy)23+. The excited-state reduction potential of these complexes ranges from +0.95 to +1.04 V vs the ferrocene/ferrocenium couple, making them potent photooxidants.
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Affiliation(s)
- Johanna C Barbour
- Department of Chemistry, Wheaton College , 501 College Avenue, Wheaton, Illinois 60187, United States
| | - Amy J I Kim
- Department of Chemistry, Wheaton College , 501 College Avenue, Wheaton, Illinois 60187, United States
| | - Elsemarie deVries
- Department of Chemistry, Wheaton College , 501 College Avenue, Wheaton, Illinois 60187, United States
| | - Sarah E Shaner
- Department of Chemistry, Benedictine University , 5700 College Road, Lisle, Illinois 60532, United States
| | - Benjamin M Lovaasen
- Department of Chemistry, Wheaton College , 501 College Avenue, Wheaton, Illinois 60187, United States
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9
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Fe(IV) alkylidenes are actually Fe(II), and a related octahedral Fe(II) “alkylidene” is a conjugated vinyl complex. Polyhedron 2016. [DOI: 10.1016/j.poly.2016.04.030] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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10
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Jacobs BP, Wolczanski PT, Lobkovsky EB. Oxidatively Triggered Carbon–Carbon Bond Formation in Ene-amide Complexes. Inorg Chem 2016; 55:4223-32. [DOI: 10.1021/acs.inorgchem.5b02990] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Brian P. Jacobs
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Peter T. Wolczanski
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Emil B. Lobkovsky
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
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Suárez-Pantiga S, Colas K, Johansson MJ, Mendoza A. Scalable Synthesis of Piperazines Enabled by Visible-Light Irradiation and Aluminum Organometallics. Angew Chem Int Ed Engl 2015; 54:14094-8. [PMID: 26337253 PMCID: PMC4648034 DOI: 10.1002/anie.201505608] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Indexed: 01/09/2023]
Abstract
The development of more active C-H oxidation catalysts has inspired a rapid, scalable, and stereoselective assembly of multifunctional piperazines through a [3+3] coupling of azomethine ylides. A combination of visible-light irradiation and aluminum organometallics is essential to promote this transformation, which introduces visible-light photochemistry of main-group organometallics and sets the basis for new and promising catalysts.
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Affiliation(s)
- Samuel Suárez-Pantiga
- Department of Organic Chemistry and Berzelii EXSELENT Center for Porous Materials, Stockholm UniversityArrhenius Laboratory, 10691 Stockholm (Sweden) E-mail: Homepage: http://www.organ.su.se/am/
| | - Kilian Colas
- Department of Organic Chemistry and Berzelii EXSELENT Center for Porous Materials, Stockholm UniversityArrhenius Laboratory, 10691 Stockholm (Sweden) E-mail: Homepage: http://www.organ.su.se/am/
| | - Magnus J Johansson
- Innovative Medicines, Cardiovascular and Metabolic Diseases, Medicinal Chemistry, AstraZeneca R&DPepparedsleden 1, 43183 Mölndal (Sweden)
| | - Abraham Mendoza
- Department of Organic Chemistry and Berzelii EXSELENT Center for Porous Materials, Stockholm UniversityArrhenius Laboratory, 10691 Stockholm (Sweden) E-mail: Homepage: http://www.organ.su.se/am/
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12
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Suárez‐Pantiga S, Colas K, Johansson MJ, Mendoza A. Scalable Synthesis of Piperazines Enabled by Visible‐Light Irradiation and Aluminum Organometallics. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201505608] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Samuel Suárez‐Pantiga
- Department of Organic Chemistry and Berzelii EXSELENT Center for Porous Materials, Stockholm University, Arrhenius Laboratory, 10691 Stockholm (Sweden) http://www.organ.su.se/am/
| | - Kilian Colas
- Department of Organic Chemistry and Berzelii EXSELENT Center for Porous Materials, Stockholm University, Arrhenius Laboratory, 10691 Stockholm (Sweden) http://www.organ.su.se/am/
| | - Magnus J. Johansson
- Innovative Medicines, Cardiovascular and Metabolic Diseases, Medicinal Chemistry, AstraZeneca R&D, Pepparedsleden 1, 43183 Mölndal (Sweden)
| | - Abraham Mendoza
- Department of Organic Chemistry and Berzelii EXSELENT Center for Porous Materials, Stockholm University, Arrhenius Laboratory, 10691 Stockholm (Sweden) http://www.organ.su.se/am/
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Lindley BM, Wolczanski PT, Cundari TR, Lobkovsky EB. First-Row Transition Metal and Lithium Pyridine-ene-amide Complexes Exhibiting N- and C-Isomers and Ligand-Based Activation of Benzylic C–H Bonds. Organometallics 2015. [DOI: 10.1021/acs.organomet.5b00385] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Brian M. Lindley
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Peter T. Wolczanski
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Thomas R. Cundari
- Department of Chemistry, Center for Advanced
Scientific Computing and Modeling (CASCaM), University of North Texas, Box 305070, Denton, Texas 76203-5070, United States
| | - Emil B. Lobkovsky
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
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Hulley EB, Williams VA, Morris WD, Wolczanski PT, Hernández-Burgos K, Lobkovsky EB, Cundari TR. Disparate reactivity from isomeric {Me 2 C(CH 2 N CHpy) 2 } and {Me 2 C(CH NCH 2 py) 2 } chelates in iron complexation. Polyhedron 2014. [DOI: 10.1016/j.poly.2014.07.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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15
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Hewage JS, Wanniarachchi S, Morin TJ, Liddle BJ, Banaszynski M, Lindeman SV, Bennett B, Gardinier JR. Homoleptic nickel(II) complexes of redox-tunable pincer-type ligands. Inorg Chem 2014; 53:10070-84. [PMID: 25222027 PMCID: PMC5047063 DOI: 10.1021/ic500657e] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Different synthetic methods have been developed to prepare eight new redox-active pincer-type ligands, H(X,Y), that have pyrazol-1-yl flanking donors attached to an ortho-position of each ring of a diarylamine anchor and that have different groups, X and Y, at the para-aryl positions. Together with four previously known H(X,Y) ligands, a series of 12 Ni(X,Y)2 complexes were prepared in high yields by a simple one-pot reaction. Six of the 12 derivatives were characterized by single-crystal X-ray diffraction, which showed tetragonally distorted hexacoordinate nickel(II) centers. The nickel(II) complexes exhibit two quasi-reversible one-electron oxidation waves in their cyclic voltammograms, with half-wave potentials that varied over a remarkable 700 mV range with the average of the Hammett σ(p) parameters of the para-aryl X, Y groups. The one- and two-electron oxidized derivatives [Ni(Me,Me)2](BF4)n (n = 1, 2) were prepared synthetically, were characterized by X-band EPR, electronic spectroscopy, and single-crystal X-ray diffraction (for n = 2), and were studied computationally by DFT methods. The dioxidized complex, [Ni(Me,Me)2](BF4)2, is an S = 2 species, with nickel(II) bound to two ligand radicals. The mono-oxidized complex [Ni(Me,Me)2](BF4), prepared by comproportionation, is best described as nickel(II) with one ligand centered radical. Neither the mono- nor the dioxidized derivative shows any substantial electronic coupling between the metal and their bound ligand radicals because of the orthogonal nature of their magnetic orbitals. On the other hand, weak electronic communication occurs between ligands in the mono-oxidized complex as evident from the intervalence charge transfer (IVCT) transition found in the near-IR absorption spectrum. Band shape analysis of the IVCT transition allowed comparisons of the strength of the electronic interaction with that in the related, previously known, Robin-Day class II mixed valence complex, [Ga(Me,Me)2](2+).
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Affiliation(s)
- Jeewantha S. Hewage
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881, United States
| | - Sarath Wanniarachchi
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881, United States
| | - Tyler J. Morin
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881, United States
| | - Brendan J. Liddle
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881, United States
| | - Megan Banaszynski
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881, United States
| | - Sergey V. Lindeman
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881, United States
| | - Brian Bennett
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, United States
| | - James R. Gardinier
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881, United States
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Morris WD, Wolczanski PT, Sutter J, Meyer K, Cundari TR, Lobkovsky EB. Iron and chromium complexes containing tridentate chelates based on nacnac and imino- and methyl-pyridine components: triggering C-X bond formation. Inorg Chem 2014; 53:7467-84. [PMID: 25010819 DOI: 10.1021/ic500807y] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Nacnac-based tridentate ligands containing a pyridyl-methyl and a 2,6-dialkyl-phenylamine (i.e., (2,6-R2-C6H3N═C(Me)CH═C(Me)NH(CH2py); R = Et, {Et(nn)PM}H; R = (i)Pr, {(i)Pr(nn)PM}H) were synthesized by condensation routes. Treatment of M{N(TMS)2}THFn (M = Cr, n = 2; M = Fe, Co, n = 1; TMS = trimethylsilane; THF = tetrahydrofuran) with {(i)Pr(nn)PM}H) afforded {(i)Pr(nn)PM}MN(TMS)2 (1-M(iPr); M = Cr, Fe); {Et(nn)PM}MN(TMS)2 (1-M(Et); M = Fe, Co) was similarly obtained. {R(nn)PM}FeBr (R = (i)Pr, Et; 2-Fe(R)) were prepared from FeBr2 and {R(nn)PM}Li, and alkylated to generate {R(nn)PM}Fe(neo)Pe (R = (i)Pr, Et; 3-Fe(R)). Carbonylation of 3-Fe(R) provided {(i)Pr(nn)PM}Fe(CO(neo)Pe)CO (4-Fe(iPr)), and carbonylations of 1-Fe(R) (R = Et, (i)Pr) and 1-Cr(iPr) induced deamination to afford {R(nn)PI}Fe(CO)2 (R = (i)Pr, 5-Fe(iPr); Et, 5-Fe(Et)), where PI is pyridine-imine, and {κ(2)-N,N-pyrim-pyr}Cr(CO)4 (6-Cr(iPr)), in which the aryl-amide side of the nacnac attacked the incipient PI group. Carbon-carbon bonds were formed at the imine carbon of the {R(nn)PI} ligand. Addition of [{(i)Pr(nn)PI}(2-)](K(+)(THF)x)2 to FeCl3 generated {(i)Pr(nn)CHpy}2Fe2Cl2 (7-Fe(iPr)), and TMSN3 induced the deamination of 1-Fe(Et), but with disproportionation to provide {[Et(nn)CHpy]2}Fe (8-Fe(Et)). Ph2CN2 induced C-C bond formation with 1-Fe(iPr) via its thermal degradation to ultimately afford {(i)Pr(nn)CHpy}2(FeN═CPh2)2 (9-Fe(iPr)). The compounds were examined by X-ray crystallography (1-M(iPr), M = Cr, Fe; 1-Co(Et); 2-Fe(iPr); 4-Fe(iPr); 5-Fe(iPr); 6-Cr(iPr); 7-Fe(iPr); 8-Fe(Et); 9-Fe(iPr)), Mössbauer spectroscopy, and NMR spectroscopy. Structural parameters assessing redox noninnocence are discussed, as are structural and mechanistic consequences of the various electronic environments.
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Affiliation(s)
- Wesley D Morris
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University , Ithaca, New York 14853, United States
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17
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Williams VA, Wolczanski PT, Sutter J, Meyer K, Lobkovsky EB, Cundari TR. Iron complexes derived from {nacnac-(CH2py)2}- and {nacnac-(CH2py)(CHpy)}n ligands: stabilization of iron(II) via redox noninnocence. Inorg Chem 2014; 53:4459-74. [PMID: 24762120 DOI: 10.1021/ic5001123] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nacnac-based tetradentate chelates, {nacnac-(CH2py)2}(-) ({nn(PM)2}(-)) and {nacnac-(CH2py)(CHpy)}(n) ({nn(PM)(PI)}(n)) have been investigated in iron complexes. Treatment of Fe{N(TMS)2}2(THF) with {nn(PM)2}H afforded {nn(PM)2}FeN(TMS)2 [1-N(TMS)2], which led to {nn(PM)2}FeCl (1-Cl) from HCl and to {nn(PM)2}FeN3 (1-N3) upon salt metathesis. Dehydroamination of 1-N(TMS)2 was induced by L (L = PMe3, CO) to afford {nn(PM)(PI)}Fe(PMe3)2 [2-(PMe3)2] and {nn(PM)(PI)}FeCO (3-CO). Substitution of 2-(PMe3)2 led to {nn(PM)(PI)}Fe(PMe3)CO [2-(PMe3)CO], and exposure to a vacuum provided {nn(PM)(PI)}Fe(PMe3) (3-PMe3). Metathesis routes to {nn(PM)(PI)}FeL2 (2-L2; L = PMe3, PMe2Ph) and {nn(PM)(PI)}FeL (3-L; L = PMePh2, PPh3) from [{nn(PM)(PI)}(2-)]Li2 and FeBr2(THF)2 in the presence of L proved feasible, and 1e(-) and 2e(-) oxidation of 2-(PMe3)2 afforded 2(+)-(PMe3)2 and 2(2+)-(PMe3)2 salts. Mössbauer spectroscopy, structural studies, and calculational assessments revealed the dominance of iron(II) in both high-spin (1-X) and low-spin (2-L2 and 3-L) environments, and the redox noninnocence (RNI) of {nn(PM)(PI)}(n) [2-L2, 3-L, n = 2-; 2(+)-(PMe3)2, n = 1-; 2(2+)-(PMe3)2, n = 0]. A discussion regarding the utility of RNI in chemical reactivity is proffered.
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Affiliation(s)
- Valerie A Williams
- Baker Laboratory, Department of Chemistry & Chemical Biology, Cornell University , Ithaca, New York 14853, United States
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18
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Olivo G, Arancio G, Mandolini L, Lanzalunga O, Di Stefano S. Hydrocarbon oxidation catalyzed by a cheap nonheme imine-based iron(ii) complex. Catal Sci Technol 2014. [DOI: 10.1039/c4cy00626g] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An imine-based iron complex, prepared in situ from iron(ii), pyridine-2-carbaldehyde and 2-aminomethylpyridine, effectively catalyzes hydrocarbon oxidation at low loadings.
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Affiliation(s)
- Giorgio Olivo
- Dipartimento di Chimica
- Sapienza Università di Roma and Istituto CNR di Metodologie Chimiche (IMC-CNR)
- Sezione Meccanismi di Reazione
- c/o Dipartimento di Chimica
- Sapienza Università di Roma
| | - Giorgio Arancio
- Dipartimento di Chimica
- Sapienza Università di Roma and Istituto CNR di Metodologie Chimiche (IMC-CNR)
- Sezione Meccanismi di Reazione
- c/o Dipartimento di Chimica
- Sapienza Università di Roma
| | - Luigi Mandolini
- Dipartimento di Chimica
- Sapienza Università di Roma and Istituto CNR di Metodologie Chimiche (IMC-CNR)
- Sezione Meccanismi di Reazione
- c/o Dipartimento di Chimica
- Sapienza Università di Roma
| | - Osvaldo Lanzalunga
- Dipartimento di Chimica
- Sapienza Università di Roma and Istituto CNR di Metodologie Chimiche (IMC-CNR)
- Sezione Meccanismi di Reazione
- c/o Dipartimento di Chimica
- Sapienza Università di Roma
| | - Stefano Di Stefano
- Dipartimento di Chimica
- Sapienza Università di Roma and Istituto CNR di Metodologie Chimiche (IMC-CNR)
- Sezione Meccanismi di Reazione
- c/o Dipartimento di Chimica
- Sapienza Università di Roma
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19
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Sazama GT, Betley TA. Multiple, disparate redox pathways exhibited by a tris(pyrrolido)ethane iron complex. Inorg Chem 2013; 53:269-81. [PMID: 24320208 DOI: 10.1021/ic402210j] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Iron(III) complexes of the tris(pyrrolide)ethane trianion have been synthesized by reaction of one- and two-electron oxidants with [(tpe)Fe(THF)][Li(THF)4] (tpe = tris(5-mesitylpyrrolyl)ethane). X-ray crystallography, (57)Fe Mössbauer, (1)H NMR and EPR spectroscopy, SQUID magnetometry, and density functional theory calculations were employed to rigorously establish the iron 3+ oxidation state. All oxidants employed are proposed to operate via an inner-sphere electron transfer mechanism. Dialkyl peroxides and dibenzyldisulfide served to oxidize iron by one electron, and group transfer of an aryl nitrene unit to the Fe(2+) starting material resulted in formation of Fe(3+) amido species following H-atom abstraction by a presumed nitrenoid intermediate. Single electron transfer to and from diphenyldiazoalkane was also observed to yield a diphenyldiazomethanyl radical anion antiferromagnetically coupled to the S = 5/2 Fe(3+). Isolation of Fe(3+) complexes of tpe, in comparison with previous results wherein the tpe ligand was the redox active moiety, presents an unusual juxtaposition of two noncommunicating redox reservoirs, each accessible via different reaction pathways (namely, inner- and outer-sphere electron transfer).
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Affiliation(s)
- Graham T Sazama
- Department of Chemistry and Chemical Biology, Harvard University , 12 Oxford Street, Cambridge, Massachusetts 02138, United States
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20
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Olatunji-Ojo OA, Cundari TR. C–H Activation by Multiply Bonded Complexes with Potentially Noninnocent Ligands: A Computational Study. Inorg Chem 2013; 52:8106-13. [DOI: 10.1021/ic400804x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Olayinka A. Olatunji-Ojo
- Department of Chemistry
and Center for Advanced Scientific
Computing and Modeling (CASCaM), University of North Texas, 1155 Union Circle, #305070 Denton, Texas 76203-5070,
United States
| | - Thomas R. Cundari
- Department of Chemistry
and Center for Advanced Scientific
Computing and Modeling (CASCaM), University of North Texas, 1155 Union Circle, #305070 Denton, Texas 76203-5070,
United States
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21
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Klein A, Krest A, Nitsche S, Stirnat K, Valldor M. First Homoleptic Complexes of the Tridentate Pyridine‐2,6‐ditetrazolate Ligand. Eur J Inorg Chem 2013. [DOI: 10.1002/ejic.201201473] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Axel Klein
- Department für Chemie, Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 Köln, Germany, http://www.klein.uni‐koeln.de/
| | - Alexander Krest
- Department für Chemie, Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 Köln, Germany, http://www.klein.uni‐koeln.de/
| | - Sara Nitsche
- Department für Chemie, Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 Köln, Germany, http://www.klein.uni‐koeln.de/
| | - Kathrin Stirnat
- Department für Chemie, Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 Köln, Germany, http://www.klein.uni‐koeln.de/
| | - Martin Valldor
- II. Physikalisches Institut, Universität zu Köln, Zuelpicher Str. 77, 50937 Köln, Germany, http://http:/www.ph2.uni‐koeln.de
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22
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Frazier BA, Williams VA, Wolczanski PT, Bart SC, Meyer K, Cundari TR, Lobkovsky EB. C-C bond formation and related reactions at the CNC backbone in (smif)FeX (smif = 1,3-di-(2-pyridyl)-2-azaallyl): dimerizations, 3 + 2 cyclization, and nucleophilic attack; transfer hydrogenations and alkyne trimerization (X = N(TMS)2, dpma = (di-(2-pyridyl-methyl)-amide)). Inorg Chem 2013; 52:3295-312. [PMID: 23448130 DOI: 10.1021/ic302783y] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Molecular orbital analysis depicts the CNC(nb) backbone of the smif (1,3-di-(2-pyridyl)-2-azaallyl) ligand as having singlet diradical and/or ionic character where electrophilic or nucleophilic attack is plausible. Reversible dimerization of (smif)Fe{N(SiMe3)2} (1) to [{(Me3Si)2N}Fe]2(μ-κ(3),κ(3)-N,py2-smif,smif) (2) may be construed as diradical coupling. A proton transfer within the backbone-methylated, and o-pyridine-methylated smif of putative ((b)Me2(o)Me2smif)FeN(SiMe3)2 (8) provides a route to [{(Me3Si)2N}Fe]2(μ-κ(4),κ(4)-N,py2,C-((b)Me,(b)CH2,(o)Me2(smif)H))2 (9). A 3 + 2 cyclization of ditolyl-acetylene occurs with 1, leading to the dimer [{2,5-di(pyridin-2-yl)-3,4-di-(p-tolyl-2,5-dihydropyrrol-1-ide)}FeN(SiMe3)2]2 (11), and the collateral discovery of alkyne cyclotrimerization led to a brief study that identified Fe(N(SiMe3)2(THF) as an effective catalyst. Nucleophilic attack by (smif)2Fe (13) on (t)BuNCO and (2,6-(i)Pr2C6H3)NCO afforded (RNHCO-smif)2Fe (14a, R = (t)Bu; 14b, 2,6-(i)PrC6H3). Calculations suggested that (dpma)2Fe (15) would favorably lose dihydrogen to afford (smif)2Fe (13). H2-transfer to alkynes, olefins, imines, PhN═NPh, and ketones was explored, but only stoichiometric reactions were affected. Some physical properties of the compounds were examined, and X-ray structural studies on several dinuclear species were conducted.
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Affiliation(s)
- Brenda A Frazier
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, USA
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23
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Volpe EC, Wolczanski PT, Darmon JM, Lobkovsky EB. Syntheses and characterizations of α-iminopyridine compounds (alkylNCHpy)2Fe(L/Xn), and an assessment of redox non-innocence. Polyhedron 2013. [DOI: 10.1016/j.poly.2012.08.060] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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24
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Williams VA, Hulley EB, Wolczanski PT, Lancaster KM, Lobkovsky EB. Exploring the limits of redox non-innocence: pseudo square planar [{κ4-Me2C(CH2NCHpy)2}Ni]n (n = 2+, 1+, 0, −1, −2) favor Ni(ii). Chem Sci 2013. [DOI: 10.1039/c3sc50743b] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Palmer JH, Lancaster KM. Molecular redox: revisiting the electronic structures of the group 9 metallocorroles. Inorg Chem 2012; 51:12473-82. [PMID: 23116160 DOI: 10.1021/ic3018826] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The electronic structures of monocationic tris[(5,10,15-pentafluorophenyl)-corrolato]iridium compounds, [Ir(tpfc)L2](+), where L = 4-cyanopyridine [1](+), pyridine [2](+), 4-methoxypyridine [3](+), or 4-(N,N'-dimethylamino)pyridine [4](+), have been probed by electron paramagnetic resonance (EPR) spectroscopy, Ir L3,2-edge X-ray absorption spectroscopy (XAS), UV/visible (UV-vis) spectroelectrochemistry, and density functional theoretical (DFT) calculations. The data demonstrate that these complexes, which have been previously formulated as either of the limiting cases [Ir(III)(tpfc(•))L2](+) or [Ir(IV)(tpfc)L2](+), are best described as possessing a singly occupied molecular orbital (SOMO) dominated by tpfc with small but significant Ir admixture. EPR g-values and electronic absorption spectra are reproduced well using a simple DFT approach. These quantities depend profoundly upon Ir orbital contribution to the SOMO. To wit, the calculated Ir spin population ranges from 10.6% for [1](+) to 16.3% for [4](+), reflecting increased Ir d mixing into the SOMO with increasingly electron-rich axial ligation. This gives rise to experimentally measured gz values ranging from 2.335 to 2.533, metal-to-ligand charge transfer (MLCT) bands ranging from 14730 and 14330 cm(-1), and [Ir(tpfc)L2](+/0) reduction potentials ranging from 0.305 to 0.035 V vs Fc(+/0). In addition, the calculated Ir character in the SOMO tracks with estimated Ir L3,2 XAS branching ratios (EBR), reflecting the increasing degree of Ir d orbital character upon proceeding from [1](+) to [4](+).
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Affiliation(s)
- Joshua H Palmer
- Beckman Institute , California Institute of Technology, Pasadena, California 91125, United States
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Frazier BA, Wolczanski PT, Keresztes I, DeBeer S, Lobkovsky EB, Pierpont AW, Cundari TR. Synthetic approaches to (smif)2Ti (smif = 1,3-di-(2-pyridyl)-2-azaallyl) reveal redox non-innocence and C-C bond-formation. Inorg Chem 2012; 51:8177-86. [PMID: 22830452 DOI: 10.1021/ic300590t] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Attempted syntheses of (smif)(2)Ti (smif =1,3-di-(2-pyridyl)-2-azaallyl) based on metatheses of TiCl(n)L(m) (n = 2-4) with M(smif) (M = Li, Na), in the presence of a reducing agent (Na/Hg) when necessary, failed, but several apparent Ti(II) species were identified by X-ray crystallography and multidimensional NMR spectroscopy: (smif){Li(smif-smif)}Ti (1, X-ray), [(smif)Ti](2)(μ-κ(3),κ(3)-N,N(py)(2)-smif,smif) (2), (smif)Ti(κ(3)-N,N(py)(2)-smif,(smif)H) (3), and (smif)Ti(dpma) (4, dpma = di-2-pyridylmethyl-amide). NMR spectroscopy and K-edge XAS showed that each compound possesses ligands that are redox noninnnocent, such that d(1) Ti(III) centers AF-couple to ligand radicals: (smif){Li(smif-smif)(2-)}Ti(III) (1), [(smif(2-))Ti(III)](2)(μ-κ(3),κ(3)-N,N(py)(2)-smif,smif) (2), [(smif(2-))Ti(III)](κ(3)-N,N(py)(2)-smif,(smif)H) (3), and (smif(2-))Ti(III)(dpma) (4). The instability of (smif)(2)Ti relative to its C-C coupled dimer, 2, is rationalized via the complementary nature of the amide and smif radical dianion ligands, which are also common to 3 and 4. Calculations support this contention.
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Affiliation(s)
- Brenda A Frazier
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
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