1
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Mena A, Luna JR, MacGregor F, Landa EN, Metta-Magaña A, Lee WY, Fortier S. Photoinduced Cleavage of a Strained N-C Bond in an Iron Complex Supported by Super-Bulky Amidinate and Guanidinate Ligands. Inorg Chem 2024; 63:5351-5364. [PMID: 38481142 DOI: 10.1021/acs.inorgchem.3c03953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/26/2024]
Abstract
The reaction of Fe2(mes)4 with the super-bulky amidines and guanidines HLAr*-R (LAr*-R = [(Ar*N)2C(R)]-, Ar* = 2,6-bis(diphenylmethyl)-4-tert-butylphenyl), R = Me (LAr*-Me), tBu (LAr*-tBu), Ph (LAr*-Ph), NiPr2 (LAr*-iPr2N), and Pip (LAr*-Pip)) gives access to the three-coordinate iron-mesityl complexes (LAr*-R)Fe(mes) only where LAr*-R = LAr*-Me, LAr*-Ph, or LAr*-Pip. Subsequent protonolysis with the N-atom transfer reagent Hdbabh (Hdbabh = 2,3:5,6-dibenzo-7-azabicyclo[2.2.1]hepta-2,5-diene) is limited in success, providing in one instance a few crystals of four-coordinate (LAr*-Me)Fe(dbabh)(Hdbabh), while three-coordinate (LAr*-Pip)Fe(dbabh) is synthesized reproducibly. Complexes (LAr*-Me)Fe(dbabh)(Hdbabh) and (LAr*-Pip)Fe(dbabh) are thermally insensitive in solution to temperatures of up to 100 °C. On the other hand, both (LAr*-Me)Fe(dbabh)(Hdbabh) and (LAr*-Pip)Fe(dbabh) show sensitivity to blue LED light (395 nm), undergoing photochemical transformations. For instance, the photolysis of (LAr*-Me)Fe(dbabh)(Hdbabh) leads to N-C bond scission and C-C bond coupling across the -dbabh moieties to give four-coordinate (LAr*-Me)Fe(N=dbabh-dbabhNH2). Photolyzing pyridine-d5 (py-d5) solutions of (LAr*-Pip)Fe(dbabh) at -5 °C produces a new paramagnetic photoproduct, [P]. Due to the thermal sensitivity of compound [P], it has eluded structural characterization; yet, Evans' method measurements suggest that the iron(II) oxidation state is maintained, thereby pointing to the -dbabh moiety as the locus of chemical change. In line with this assessment, addition of excess Me3SiCl to solutions of [P] produces the iron(II) complex (LAr*-Pip)FeCl(py-d5) as shown by 1H NMR spectroscopy. Gas chromatography/mass spectrometry analysis of the solutions of [P] shows a peak in the chromatogram with a molecular mass corresponding to a formulation of C14H11N that cannot be attributed to Hdbabh. This provides evidence for the photochemical-induced isomerization of the -dbabh ligand, revealing a heretofore unknown photochemical sensitivity of this N atom transfer reagent.
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Affiliation(s)
- Asiel Mena
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
| | - Juan R Luna
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
| | - Frank MacGregor
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
| | - Elizabeth Noriega Landa
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
| | - Alejandro Metta-Magaña
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
| | - Wen-Yee Lee
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
| | - Skye Fortier
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
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2
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Soussi K, Jeanneau E, Maldivi P, Clémancey M, Latour JM, Khrouz L, Lorentz C, Daniele S, Mishra S. N-Alkyl substituted triazenide-bridged homoleptic iron(II) dimers with an exceptionally short Fe-Fe bond. Dalton Trans 2024; 53:1439-1444. [PMID: 38193200 DOI: 10.1039/d3dt03132b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
Dinuclear transition metal complexes with direct metal-metal interactions have the potential to generate unique reactivities and properties. Using asymmetric triazine ligands HN3tBuR (R = Et, iPr, nBu) featuring different alkyl substituents at 1,3-N centers, we report here the first rational synthesis of 'tetragonal lantern' type Fe(II) triazenides [Fe2(N3tBuR)4] [R = Et (1), iPr (2), nBu (3)] having an exceptionally short Fe-Fe distance (2.167-2.174 Å). Unlike the previously reported lantern structures with related amidinate or guanidinate ligands, highly air-sensitive 1-3 show a lower spin ground state, as indicated by Mössbauer, 1H NMR and DFT studies.
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Affiliation(s)
- Khaled Soussi
- Université Claude Bernard Lyon 1, CNRS, UMR 5256, Institut de Recherches sur la Catalyse et l'Environnement de Lyon (IRCELYON), 2 avenue Albert Einstein, 69626 Villeurbanne, France.
| | - Erwann Jeanneau
- Université Claude Bernard Lyon 1, Centre de Diffractométrie Henri Longchambon, 5 rue de La Doua, 69100 Villeurbanne, France
| | - Pascale Maldivi
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, DIESE, SyMMES, F-38000 Grenoble, France
| | - Martin Clémancey
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, DIESE, LCBM, pmb, F-38000 Grenoble, France
| | - Jean-Marc Latour
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, DIESE, LCBM, pmb, F-38000 Grenoble, France
| | - Lhoussain Khrouz
- Université de Lyon, ENS de Lyon, CNRS, Université Lyon 1, Laboratoire de Chimie, F69342, Lyon, France
| | - Chantal Lorentz
- Université Claude Bernard Lyon 1, CNRS, UMR 5256, Institut de Recherches sur la Catalyse et l'Environnement de Lyon (IRCELYON), 2 avenue Albert Einstein, 69626 Villeurbanne, France.
| | - Stéphane Daniele
- Université Claude Bernard Lyon 1, CNRS-UMR 5218, CP2M-ESCPE Lyon, 43 Bd du 11 Nov. 1978, 69616, Villeurbanne, France.
| | - Shashank Mishra
- Université Claude Bernard Lyon 1, CNRS, UMR 5256, Institut de Recherches sur la Catalyse et l'Environnement de Lyon (IRCELYON), 2 avenue Albert Einstein, 69626 Villeurbanne, France.
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3
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Evans MJ, Anker MD, McMullin CL, Coles MP. Reductive Coupling of a Diazoalkane Derivative Promoted by a Potassium Aluminyl and Elimination of Dinitrogen to Generate a Reactive Aluminium Ketimide. Chemistry 2023; 29:e202302903. [PMID: 37786384 PMCID: PMC10946750 DOI: 10.1002/chem.202302903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 09/27/2023] [Accepted: 09/28/2023] [Indexed: 10/04/2023]
Abstract
The reaction of 9-diazo-9H-fluorene (fluN2 ) with the potassium aluminyl K[Al(NON)] ([NON]2- =[O(SiMe2 NDipp)2 ]2- , Dipp=2,6-iPr2 C6 H3 ) affords K[Al(NON)(κN1 ,N3 -{(fluN2 )2 })] (1). Structural analysis shows a near planar 1,4-di(9H-fluoren-9-ylidene)tetraazadiide ligand that chelates to the aluminium. The thermally induced elimination of dinitrogen from 1 affords the neutral aluminium ketimide complex, Al(NON)(N=flu)(THF) (2) and the 1,2-di(9H-fluoren-9-yl)diazene dianion as the potassium salt, [K2 (THF)3 ][fluN=Nflu] (3). The reaction of 2 with N,N'-diisopropylcarbodiimide (iPrN=C=NiPr) affords the aluminium guanidinate complex, Al(NON){N(iPr)C(N=CMe2 )N(CHflu)} (4), showing a rare example of reactivity at a metal ketimide ligand. Density functional theory (DFT) calculations have been used to examine the bonding in the newly formed [(fluN2 )2 ]2- ligand in 1 and the ketimide bonding in 2. The mechanism leading to the formation of 4 has also been studied using this technique.
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Affiliation(s)
- Matthew J. Evans
- School of Chemical and Physical SciencesVictoria University of WellingtonP.O. Box 600Wellington6012New Zealand
| | - Mathew D. Anker
- School of Chemical and Physical SciencesVictoria University of WellingtonP.O. Box 600Wellington6012New Zealand
| | | | - Martyn P. Coles
- School of Chemical and Physical SciencesVictoria University of WellingtonP.O. Box 600Wellington6012New Zealand
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4
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Gómez-Torres A, Metta-Magaña A, Fortier S. Synthesis of an Arenide Scandium Complex Accompanied by Reductively Induced C–H Activation. Organometallics 2022. [DOI: 10.1021/acs.organomet.2c00409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Alejandra Gómez-Torres
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
| | - Alejandro Metta-Magaña
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
| | - Skye Fortier
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
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5
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Peddarao T, Baishya A, Sarkar N, Acharya R, Nembenna S. Conjugated Bis‐Guanidines (CBGs) as
β
‐Diketimine Analogues: Synthesis, Characterization of CBGs/Their Lithium Salts and CBG Li Catalyzed Addition of B−H and TMSCN to Carbonyls. Eur J Inorg Chem 2021. [DOI: 10.1002/ejic.202100141] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Thota Peddarao
- School of Chemical Sciences National Institute of Science Education and Research (NISER) Homi Bhabha National Institute (HBNI) Bhubaneswar 752050 India
| | - Ashim Baishya
- School of Chemical Sciences National Institute of Science Education and Research (NISER) Homi Bhabha National Institute (HBNI) Bhubaneswar 752050 India
| | - Nabin Sarkar
- School of Chemical Sciences National Institute of Science Education and Research (NISER) Homi Bhabha National Institute (HBNI) Bhubaneswar 752050 India
| | - Rudresh Acharya
- School of Biological Sciences National Institute of Science Education and Research (NISER) Homi Bhabha National Institute (HBNI) Bhubaneswar 752050 India
| | - Sharanappa Nembenna
- School of Chemical Sciences National Institute of Science Education and Research (NISER) Homi Bhabha National Institute (HBNI) Bhubaneswar 752050 India
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6
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Sengupta D, Sandoval-Pauker C, Schueller E, Encerrado-Manriquez AM, Metta-Magaña A, Lee WY, Seshadri R, Pinter B, Fortier S. Isolation of a Bimetallic Cobalt(III) Nitride and Examination of Its Hydrogen Atom Abstraction Chemistry and Reactivity toward H 2. J Am Chem Soc 2020; 142:8233-8242. [PMID: 32279486 DOI: 10.1021/jacs.0c00291] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Room temperature photolysis of the bis(azide)cobaltate(II) complex [Na(THF)x][(ketguan)Co(N3)2] (ketguan = [(tBu2CN)C(NDipp)2]-, Dipp = 2,6-diisopropylphenyl) (3a) in THF cleanly forms the binuclear cobalt nitride Na(THF)4{[(ketguan)Co(N3)]2(μ-N)} (1). Compound 1 represents the first example of an isolable, bimetallic cobalt nitride complex, and it has been fully characterized by spectroscopic, magnetic, and computational analyses. Density functional theory supports a CoIII═N═CoIII canonical form with significant π-bonding between the cobalt centers and the nitride atom. Unlike other group 9 bridging nitride complexes, no radical character is detected at the bridging N atom of 1. Indeed, 1 is unreactive toward weak C-H donors and even cocrystallizes with a molecule of cyclohexadiene (CHD) in its crystallographic unit cell to give 1·CHD as a room temperature stable product. Notably, addition of pyridine to 1 or photolyzed solutions of [(ketguan)Co(N3)(py)]2 (4a) leads to destabilization via activation of the nitride unit, resulting in the mixed-valent Co(II)/Co(III) bridged imido species [(ketguan)Co(py)][(ketguan)Co](μ-NH)(μ-N3) (5) formed from intermolecular hydrogen atom abstraction (HAA) of strong C-H bonds (BDE ∼ 100 kcal/mol). Kinetic rate analysis of the formation of 5 in the presence of C6H12 or C6D12 gives a KIE = 2.5 ± 0.1, supportive of a HAA formation pathway. The reactivity of our system was further probed by photolyzing benzene/pyridine solutions of 4a under H2 and D2 atmospheres (150 psi), which leads to the exclusive formation of the bis(imido) complexes [(ketguan)Co(μ-NH)]2 (6) and [(ketguan)Co(μ-ND)]2 (6-D), respectively, as a result of dihydrogen activation. These results provide unique insights into the chemistry and electronic structure of late 3d metal nitrides while providing entryway into C-H activation pathways.
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Affiliation(s)
- Debabrata Sengupta
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
| | | | - Emily Schueller
- Materials Department and Materials Research Laboratory, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | | | - Alejandro Metta-Magaña
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
| | - Wen-Yee Lee
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
| | - Ram Seshadri
- Materials Department and Materials Research Laboratory, University of California, Santa Barbara, Santa Barbara, California 93106, United States.,Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Balazs Pinter
- Department of Chemistry, Universidad Técnica Federico Santa María, Valparaíso 2390123, Chile
| | - Skye Fortier
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
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7
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Gyton MR, Leverett AR, Cole ML, McKay AI. Bulky bis(aryl)triazenides: just aspiring amidinates? A structural and spectroscopic study. Dalton Trans 2020; 49:5653-5661. [DOI: 10.1039/d0dt00285b] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The triazenide ligand is compared to the isoelectronic formamidinate with regards donor capacity, coordination chemistry and capacity to stabilise reactive main group species.
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Affiliation(s)
- Matthew R. Gyton
- School of Chemistry
- University of New South Wales
- Kensington
- Australia
| | | | - Marcus L. Cole
- School of Chemistry
- University of New South Wales
- Kensington
- Australia
| | - Alasdair I. McKay
- School of Chemistry
- University of New South Wales
- Kensington
- Australia
- School of Chemistry
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8
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Settineri NS, Shiau AA, Arnold J. Dioxygen reacts with metal-carbon bonds in thorium dialkyls to produce bis(alkoxides). Dalton Trans 2019; 48:5569-5573. [PMID: 30938732 DOI: 10.1039/c9dt00811j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Exposure of bis-amidinate and -guanidinate supported thorium dialkyl complexes to dioxygen results in facile oxygen atom insertion and formation of the corresponding thorium bis(alkoxide) species. Preliminary mechanistic studies suggest a radical propagation mechanism is operative. All new complexes were fully characterized by 1H and 13C NMR spectroscopy, IR, EA and X-ray crystallography.
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Affiliation(s)
- Nicholas S Settineri
- Department of Chemistry, University of California, Berkeley, California 94720, USA.
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9
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Wong GF, Yeung LF, Tsoi HY, Chan H, Chiang M, Lee HK. A Mononuclear Iron(II) Bis(guanidinate) Complex: Synthesis, Structure, and Reactivity. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201800815] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- George Fai Wong
- Department of Chemistry The Chinese University of Hong Kong Shatin New Territories Hong Kong
| | - Lai Fong Yeung
- Department of Chemistry The Chinese University of Hong Kong Shatin New Territories Hong Kong
| | - Ho Yin Tsoi
- Department of Chemistry The Chinese University of Hong Kong Shatin New Territories Hong Kong
| | - Hoi‐Shan Chan
- Department of Chemistry The Chinese University of Hong Kong Shatin New Territories Hong Kong
| | - Ming‐Hsi Chiang
- Institute of Chemistry Academia Sinica 128 Academia Road Sec. 2, Nankang 115 Taipei Taiwan
| | - Hung Kay Lee
- Department of Chemistry The Chinese University of Hong Kong Shatin New Territories Hong Kong
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10
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Settineri NS, Shiau AA, Arnold J. Two-electron oxidation of a homoleptic U(iii) guanidinate complex by diphenyldiazomethane. Chem Commun (Camb) 2018; 54:10913-10916. [PMID: 30206592 DOI: 10.1039/c8cc06514d] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Reaction of the first homoleptic U(iii) guanidinate complex with diphenyldiazomethane results in two-electron oxidation of U(iii) to U(v) and isolation of a U(v) hydrazido complex. Corresponding U(v) imido, U(v) oxo, and U(iv) azido complexes were also synthesized for structural comparison.
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Affiliation(s)
- Nicholas S Settineri
- Department of Chemistry, University of California, Berkeley, California 94720, USA.
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11
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Murillo CA. Adventures in divalent early transition metal coordination chemistry: On the way to metal–metal bonded species. Inorganica Chim Acta 2017. [DOI: 10.1016/j.ica.2016.12.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Maity AK, Murillo J, Metta-Magaña AJ, Pinter B, Fortier S. A Terminal Iron(IV) Nitride Supported by a Super Bulky Guanidinate Ligand and Examination of Its Electronic Structure and Reactivity. J Am Chem Soc 2017; 139:15691-15700. [PMID: 28953380 DOI: 10.1021/jacs.7b06919] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Utilizing the bulky guanidinate ligand [LAr*]- (LAr* = (Ar*N)2C(R), Ar* = 2,6-bis(diphenylmethyl)-4-tert-butylphenyl, R = NCtBu2) for kinetic stabilization, the synthesis of a rare terminal Fe(IV) nitride complex is reported. UV irradiation of a pyridine solution of the Fe(II) azide [LAr*]FeN3(py) (3-py) at 0 °C cleanly generates the Fe(IV) nitride [LAr*]FeN(py) (1). The 15N NMR spectrum of the 115N (50% Fe≡15N) isotopomer shows a resonance at 1016 ppm (vs externally referenced CH3NO2 at 380 ppm), comparable to that known for other terminal iron nitrides. Notably, the computed structure of 1 reveals an iron center with distorted tetrahedral geometry, τ4 = 0.72, featuring a short Fe≡N bond (1.52 Å). Inspection of the frontier orbital ordering of 1 shows a relatively small HOMO/LUMO gap with the LUMO comprised by Fe(dxz,yz)N(px,y) π*-orbitals, a splitting that is manifested in the electronic absorption spectrum of 1 (λ = 610 nm, ε = 1375 L·mol-1·cm-1; λ = 613 nm (calcd)). Complex 1 persists in low-temperature solutions of pyridine but becomes unstable at room temperature, gradually converting to the Fe(II) hydrazide product [κ2-(tBu2CN)C(η6-NAr*)(N-NAr*)]Fe (4) upon standing via intramolecular N-atom insertion. This reactivity of the Fe≡N moiety was assessed through molecular orbital analysis, which suggests electrophilic character at the nitride functionality. Accordingly, treatment of 1 with the nucleophiles PMe2Ph and Ar-N≡C (Ar = 2,6-dimethylphenyl) leads to partial N-atom transfer and formation of the Fe(II) addition products [LAr*]Fe(N═PMe2Ph)(py) (5) and [LAr*]Fe(N═C═NAr)(py) (6). Similarly, 1 reacts with PhSiH3 to give [LAr*]Fe[N(H)(SiH2Ph)](py) (7) which Fukui analysis shows to proceed via electrophilic insertion of the nitride into the Si-H bond.
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Affiliation(s)
- Arnab K Maity
- Department of Chemistry, University of Texas at El Paso , El Paso, Texas 79968, United States
| | - Jesse Murillo
- Department of Chemistry, University of Texas at El Paso , El Paso, Texas 79968, United States
| | | | - Balazs Pinter
- Computational OrganoMetallic and Inorganic Chemistry Group, Eenheid Algemene Chemie, Vrije Universiteit Brussel , Pleinlaan 2, Brussels 1050, Belgium
| | - Skye Fortier
- Department of Chemistry, University of Texas at El Paso , El Paso, Texas 79968, United States
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13
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Aguilar-Calderón JR, Metta-Magaña AJ, Noll B, Fortier S. C(sp3
)−H Oxidative Addition and Transfer Hydrogenation Chemistry of a Titanium(II) Synthon: Mimicry of Late-Metal Type Reactivity. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201607441] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
| | | | - Bruce Noll
- Bruker AXS Inc.; 5465 East Cheryl Parkway Madison WI 53711 USA
| | - Skye Fortier
- Department of Chemistry; University of Texas at El Paso; El Paso TX 79968 USA
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14
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Aguilar-Calderón JR, Metta-Magaña AJ, Noll B, Fortier S. C(sp 3 )-H Oxidative Addition and Transfer Hydrogenation Chemistry of a Titanium(II) Synthon: Mimicry of Late-Metal Type Reactivity. Angew Chem Int Ed Engl 2016; 55:14101-14105. [PMID: 27709763 DOI: 10.1002/anie.201607441] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 09/12/2016] [Indexed: 12/14/2022]
Abstract
Two-electron reduction of the TiIV compound (ket guan)(ImDipp N)Ti(OTf)2 (3) gives the arene-masked complex (ket guan)(η6 -ImDipp N)Ti (1) in excellent yield. Upon standing in solution, 1 converts to a TiIV metallacycle (4) through dehydrogenation of a pendant isopropyl group. Spectroscopic evidence shows this transformation initially proceeds via the oxidative addition of a C(sp3 )-H bond and can be reversed upon exposure of 4 to H2 . Interestingly, treatment of 1 with cyclohexene gives cyclohexane and 4 via a titanium-mediated transfer hydrogenation reaction, a process that can be extended to catalytically hydrogenate other unsaturated hydrocarbons under mild conditions. These results, rare for the early-metals, suggest 1 possesses chemical characteristics reminiscent of noble, late-metals.
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Affiliation(s)
| | | | - Bruce Noll
- Bruker AXS Inc., 5465 East Cheryl Parkway, Madison, WI, 53711, USA
| | - Skye Fortier
- Department of Chemistry, University of Texas at El Paso, El Paso, TX, 79968, USA.
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15
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Castillo M, Barreda O, Maity AK, Barraza B, Lu J, Metta-Magaña AJ, Fortier S. Advances in Guanidine Ligand Design: Synthesis of a Strongly Electron-Donating, Imidazolin-2-iminato Functionalized Guanidinate and its Properties on Iron. J COORD CHEM 2016; 69:2003-2014. [PMID: 28216799 PMCID: PMC5312970 DOI: 10.1080/00958972.2016.1167198] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 02/18/2016] [Indexed: 10/22/2022]
Abstract
Imidazolin-2-imines (ImRN-), derived from N-heterocylic carbenes, have been shown to be strong electron donors when directly coordinated to metals or when used as a substituent in larger ligand frameworks. In an attempt to enhance the electron-donating properties of the popular guanidine ligand class, the effect of appending an ImRN- backbone onto a guanidinate scaffold was investigated. Addition of 1 equiv of [Li(Et2O)][Im tBuN] to the aryl carbodiimide (dippN)2C (dipp = 2,6-diisopropylphenyl) cleanly affords the lithium Im tBuN-functionalized guanidinate [Li(THF)2][(Im tBuN)C(Ndipp)2] (1). Subsequent metalation of the ligand with FeBr2 gives the yellow Fe(II) complex {[(Im tBuN)C(Ndipp)2]FeBr}2 (4) in good yield. Solid-state structural analyses of both 1 and 4 shows the Im tBuN- group acts as a non-coordinating backbone substituent. Direct structural comparison of 4 to the closely related guanidinate and ketimine-guanidinate complexes {[(X)C(Ndipp)2]FeBr}2 (X = t Bu2C=N (5); N( i Pr)2 (6)), differing only in their backbone, reveals a detectable resonance contribution of the Im tBuN- group to the guanidinate ligand electronic structure. Moreover, the Fe(II)/Fe(III) redox couple of 4 (E1/2 = -0.67 V) is cathodically shifted by greater than 200 mV from the oxidation potentials of 5 (E1/2 = -0.42 V) and 6 (E1/2 = -0.45 V), demonstrating the [(Im tBuN)C(Ndipp)2]- system to be a quantifiably superior electron donor.
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Affiliation(s)
| | - Omar Barreda
- Department of Chemistry, University of Texas at El Paso, El Paso, TX 79968
| | - Arnab K. Maity
- Department of Chemistry, University of Texas at El Paso, El Paso, TX 79968
| | - Brian Barraza
- Department of Chemistry, University of Texas at El Paso, El Paso, TX 79968
| | - Jeffrey Lu
- Department of Chemistry, University of Texas at El Paso, El Paso, TX 79968
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106
| | | | - Skye Fortier
- Department of Chemistry, University of Texas at El Paso, El Paso, TX 79968
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Peddarao T, Baishya A, Barman MK, Kumar A, Nembenna S. Metal-free access of bulky N,N′-diarylcarbodiimides and their reduction: bulky N,N′-diarylformamidines. NEW J CHEM 2016. [DOI: 10.1039/c6nj00907g] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A facile synthetic protocol for the preparation of N,N′-diarylcarbodiimides and their reduction with sodium borohydride in ethanol to obtain N,N′-diarylformamidines has been demonstrated.
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Affiliation(s)
- Thota Peddarao
- School of Chemical Sciences
- National Institute of Science Education and Research (NISER)
- Bhubaneswar
- India
| | - Ashim Baishya
- School of Chemical Sciences
- National Institute of Science Education and Research (NISER)
- Bhubaneswar
- India
| | - Milan Kr. Barman
- School of Chemical Sciences
- National Institute of Science Education and Research (NISER)
- Bhubaneswar
- India
| | - Ajay Kumar
- School of Chemical Sciences
- National Institute of Science Education and Research (NISER)
- Bhubaneswar
- India
| | - Sharanappa Nembenna
- School of Chemical Sciences
- National Institute of Science Education and Research (NISER)
- Bhubaneswar
- India
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Francos J, González-Liste PJ, Menéndez-Rodríguez L, Crochet P, Cadierno V, Borge J, Antiñolo A, Fernández-Galán R, Carrillo-Hermosilla F. Half-Sandwich Guanidinate-Osmium(II) Complexes: Synthesis and Application in the Selective Dehydration of Aldoximes. Eur J Inorg Chem 2015. [DOI: 10.1002/ejic.201501221] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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