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Tsai CP, Chen CY, Lin YL, Lan JC, Tsai ML. Catalytic Dehydrogenation of Formic Acid Promoted by Triphos-Co Complexes: Two Competing Pathways for H 2 Production. Inorg Chem 2024; 63:1759-1773. [PMID: 38217506 DOI: 10.1021/acs.inorgchem.3c02959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2024]
Abstract
In this study, we reported the synthesis and structural characterization of a triphos-CoII complex [(κ3-triphos)CoII(CH3CN)2]2+ (1) and a triphos-CoI-H complex [(κ2-triphos)HCoI(CO)2] (4). The facile synthetic pathways from 1 to [(κ3-triphos)CoII(κ2-O2CH)]+ (1') and [(κ3-triphos)CoI(CH3CN)]+ (2), respectively, as well as the interconversion between [(κ3-triphos)CoI(CO)2]+ (3) and 4 have been established. The activation energy barrier, associated with the dehydrogenation of a coordinated formate fragment in 1' yielding the corresponding 2 accompanied by the formation of H2 and CO2, was experimentally determined as 23.9 kcal/mol. With 0.01 mol % loading of 1, a maximum TON ∼ 1735 within 18 h and TOF ∼ 483 h-1 for the first 3 h could be achieved. Kinetic isotope effect (KIE) values of 2.25 (kHCOOH/kDCOOH) and 1.36 (kHCOOH/kHCOOD) for the dehydrogenation of formic acid and its deuterated derivatives, respectively, implicate that the H-COOH bond cleavage is likely the rate-determining step. The catalytic mechanism proposed by density functional theory (DFT) calculations coupled with experimental 1H NMR and gas chromatography-mass spectrometry (GC-MS) analysis unveils two competing pathways for H2 production; specifically, deprotonating a HCOO-H bond by a proposed Co-H intermediate C and homolytic cleavage of the CoII-H moiety of C, presumably via a dimeric Co intermediate D containing a [Co2(μ-H)2]2+ core, to yield the corresponding 2 and H2.
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Affiliation(s)
- Chou-Pen Tsai
- Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
| | - Chih-Yao Chen
- Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
| | - Yi-Lin Lin
- Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
| | - Jen-Chen Lan
- Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
| | - Ming-Li Tsai
- Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
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VanderWeide A, Prokopchuk DE. Cyclopentadienyl ring activation in organometallic chemistry and catalysis. Nat Rev Chem 2023:10.1038/s41570-023-00501-1. [PMID: 37258685 DOI: 10.1038/s41570-023-00501-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2023] [Indexed: 06/02/2023]
Abstract
The cyclopentadienyl (Cp) ligand is a cornerstone of modern organometallic chemistry. Since the discovery of ferrocene, the Cp ligand and its various derivatives have become foundational motifs in catalysis, medicine and materials science. Although largely considered an ancillary ligand for altering the stereoelectronic properties of transition metal centres, there is mounting evidence that the core Cp ring structure also serves as a reservoir for reactive protons (H+), hydrides (H-) or radical hydrogen (H•) atoms. This Review chronicles the field of Cp ring activation, highlighting the pivotal role that Cp ligands can have in electrocatalytic H2 production, N2 reduction, hydride transfer reactions and proton-coupled electron transfer.
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Parsutkar MM, Moore CE, RajanBabu TV. Activator-free single-component Co(I)-catalysts for regio- and enantioselective heterodimerization and hydroacylation reactions of 1,3-dienes. New reduction procedures for synthesis of [L]Co(I)-complexes and comparison to in situ generated catalysts. Dalton Trans 2022; 51:10148-10159. [PMID: 35734952 DOI: 10.1039/d2dt01484j] [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
Although cobalt(I) bis-phosphine complexes have been implicated in many selective C-C bond-forming reactions, until recently relatively few of these compounds have been fully characterized or have been shown to be intermediates in catalytic reactions. In this paper we present a new practical method for the synthesis and isolation of several cobalt(I)-bis-phosphine complexes and their use in Co(I)-catalyzed reactions. We find that easily prepared (in situ generated or isolated) bis-phosphine and (2,6-N-aryliminoethyl)pyridine (PDI) cobalt(II) halide complexes are readily reduced by 1,4-bis-trimethylsilyl-1,4-dihydropyrazine or commercially available lithium nitride (Li3N), leaving behind only innocuous volatile byproducts. Depending on the structures of the bis-phosphines, the cobalt(I) complex crystallizes as a phosphine-bridged species [(P∼P)(X)CoI[μ-(P∼P)]CoI(X)(P∼P)] or a halide-bridged species [(P∼P)CoI[μ-(X)]2CoI(P∼P)]. Because the side-products are innocuous, these methods can be used for the in situ generation of catalytically competent Co(I) complexes for a variety of low-valent cobalt-catalyzed reactions of even sensitive substrates. These complexes are also useful for the synthesis of rare cationic [(P∼P)CoI-η4-diene]+ X- or [(P∼P)CoI-η6-arene]+ X- complexes, which are shown to be excellent single-component catalysts for the following regioselective reactions of dienes: heterodimerizations with ethylene or methyl acrylate, hydroacylation and hydroboration. The reactivity of the single-component catalysts with the in situ generated species are also documented.
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Affiliation(s)
- Mahesh M Parsutkar
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA.
| | - Curtis E Moore
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA.
| | - T V RajanBabu
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA.
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Biswas S, Parsutkar MM, Jing SM, Pagar VV, Herbort JH, RajanBabu TV. A New Paradigm in Enantioselective Cobalt Catalysis: Cationic Cobalt(I) Catalysts for Heterodimerization, Cycloaddition, and Hydrofunctionalization Reactions of Olefins. Acc Chem Res 2021; 54:4545-4564. [PMID: 34847327 PMCID: PMC8721816 DOI: 10.1021/acs.accounts.1c00573] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
One of the major challenges facing organic synthesis in the 21st century is the utilization of abundantly available feedstock chemicals for fine chemical synthesis. Regio- and enantioselective union of easily accessible 1,3-dienes and other feedstocks like ethylene, alkyl acrylates, and aldehydes can provide valuable building blocks adorned with latent functionalities for further synthetic elaboration. Through an approach that relies on mechanistic insights and systematic examination of ligand and counterion effects, we developed an efficient cobalt-based catalytic system [(P∼P)CoX2/Me3Al] (P∼P = bisphosphine) to effect the first enantioselective heterodimerization of several types of 1,3-dienes with ethylene. In addition to simple cyclic and acyclic dienes, siloxy-1,3-dienes participate in this reaction, giving highly functionalized, nearly enantiopure silyl enolates, which can be used for subsequent C-C and C-X bond-forming reactions. As our understanding of the mechanism of this reaction improved, our attention was drawn to more challenging partners like alkyl acrylates (one of the largest volume feedstocks) as the olefin partners instead of ethylene. Prompted by the intrinsic limitations of using aluminum alkyls as the activators for this reaction, we explored the fundamental chemistry of the lesser known (P∼P)Co(I)X species and discovered that in the presence of halide sequestering agents, such as sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBARF) or (C6F5)3B, certain chiral bisphosphine complexes are superb catalysts for regio- and enantioselective heterodimerization of 1,3-dienes and alkyl acrylates. We have since found that these cationic Co(I) catalysts, most conveniently prepared in situ by reduction of the corresponding cobalt(II) halide complexes by zinc in the presence of NaBARF, promote enantioselective [2 + 2]-cycloaddition between alkynes and an astonishing variety of alkenyl derivatives to give highly functionalized cyclobutenes. In reactions between 1,3-enynes and ethylene, the [2 + 2]-cycloaddition between the alkyne and ethylene is followed by a 1,4-addition of ethylene in a tandem fashion to give nearly enantiopure cyclobutanes with an all-carbon quaternary center, giving a set of molecules that maps well into many medicinally relevant compounds. In another application, we find that the cationic Co(I)-catalysts promote highly selective hydroacylation and 1,2-hydroboration of prochiral 1,3-dienes. Further, we find that a cationic Co(I)-catalyst promotes cycloisomerization followed by hydroalkenylation of 1,6-enynes to produce highly functionalized carbo- and heterocyclic compounds. Surprisingly the regioselectivity of the alkene addition depends on whether it is a simple alkene or an acrylate, and the acrylate addition produces an uncommon Z-adduct. This Account will provide a summary of the enabling basic discoveries and the attendant developments that led to the unique cationic Co(I)-complexes as catalysts for disparate C-C and C-B bond-forming reactions. It is our hope that this Account will stimulate further work with these highly versatile catalysts which are derived from an earth-abundant metal.
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Affiliation(s)
- Souvagya Biswas
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Mahesh M Parsutkar
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Stanley M Jing
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Vinayak V Pagar
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - James H Herbort
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - T V RajanBabu
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
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Horstmann JS, Klabunde S, Hepp A, Layh M, Hansen MR, Eckert H, Würthwein E, Uhl W. Reactions of Al‐N Based Active Lewis Pairs with Ketones and 1,2‐Diketones: Insertion into Al‐N Bonds, C‐C and C‐N Bond Formation and a Tricyclic Saturated Tetraaza Compound. Eur J Inorg Chem 2020. [DOI: 10.1002/ejic.202000570] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Julia Silissa Horstmann
- Institut für Anorganische und Analytische Chemie Universität Münster Corrensstraße 30 48149 Münster Germany
| | - Sina Klabunde
- Institut für Physikalische Chemie Universität Münster Corrensstraße 30 48149 Münster Germany
| | - Alexander Hepp
- Institut für Anorganische und Analytische Chemie Universität Münster Corrensstraße 30 48149 Münster Germany
| | - Marcus Layh
- Institut für Anorganische und Analytische Chemie Universität Münster Corrensstraße 30 48149 Münster Germany
| | - Michael Ryan Hansen
- Institut für Physikalische Chemie Universität Münster Corrensstraße 30 48149 Münster Germany
| | - Hellmut Eckert
- Institut für Physikalische Chemie Universität Münster Corrensstraße 30 48149 Münster Germany
| | - Ernst‐Ulrich Würthwein
- Organisch‐chemisches Institut and Center for Multiscale Theory and Computation (CMTC) Universität Münster Corrensstrasse 40 48149 Münster Germany
| | - Werner Uhl
- Institut für Anorganische und Analytische Chemie Universität Münster Corrensstraße 30 48149 Münster Germany
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Gray M, Hines MT, Parsutkar MM, Wahlstrom AJ, Brunelli NA, RajanBabu TV. Mechanism of Cobalt-Catalyzed Heterodimerization of Acrylates and 1,3-Dienes. A Potential Role of Cationic Cobalt(I) Intermediates. ACS Catal 2020; 10:4337-4348. [PMID: 32457820 DOI: 10.1021/acscatal.9b05455] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Coupling reactions of feedstock alkenes are promising, but few of these reactions are practiced industrially. Even though recent advances in the synthetic methodology have led to excellent regio- and enantioselectivies in the dimerization reactions between 1,3-dienes and acrylates, the efficiency as measured by the turnover numbers (TON) in the catalyst has remained modest. Through a combination of reaction progress kinetic analysis (RPKA) of a prototypical dimerization reaction, characterization of isolated low-valent cobalt catalyst precursors involved, several important details of the mechanism of this reaction have emerged. (i) The prototypical reaction has an induction period that requires at least two hours of stir time to generate the competent catalyst. (ii) Reduction of a Co(II) complex to a Co(I) complex, and subsequent generation of a cationic [Co(I)]+ species are responsible for this delay. (iii) Through RPKA using in situ IR spectroscopy, same excess experiments reveal inhibition by the product towards the end of the reaction and no catalyst deactivation is observed as long as diene is present in the medium. The low TON observed is most likely the result of the inherent instability of the putative cationic Co(I)-species that catalyzes the reaction. (iv) Different excess experiments suggest that the reaction is first order in the diene and zero order in the acrylate. (v) Catalyst loading experiments show that the catalyst is first order. The orders in the various regents were further confirmed by Variable Time Normalization Analysis (VTNA). (vi) A mechanism based on oxidative dimerization [via Co(I)/Co(III)-cycle] is proposed. Based on the results of this study, it is possible to increase the TON by a factor of 10 by conducting the reaction at an increased concentration of the starting materials, especially, the diene, which seems to stabilize the catalytic species.
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Affiliation(s)
- Montgomery Gray
- Department of Chemistry and Biochemistry, The Ohio State University, 100 W. 18th Avenue, Columbus, Ohio 43210, United States
| | - Michael T. Hines
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 151 W. Woodruff, Columbus, Ohio 43210, United States
| | - Mahesh M. Parsutkar
- Department of Chemistry and Biochemistry, The Ohio State University, 100 W. 18th Avenue, Columbus, Ohio 43210, United States
| | - A. J. Wahlstrom
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 151 W. Woodruff, Columbus, Ohio 43210, United States
| | - Nicholas A. Brunelli
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 151 W. Woodruff, Columbus, Ohio 43210, United States
| | - T. V. RajanBabu
- Department of Chemistry and Biochemistry, The Ohio State University, 100 W. 18th Avenue, Columbus, Ohio 43210, United States
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Apps SL, Miller PW, Long NJ. Cobalt(-i) triphos dinitrogen complexes: activation and silyl-functionalisation of N 2. Chem Commun (Camb) 2019; 55:6579-6582. [PMID: 31112153 DOI: 10.1039/c9cc01496a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The cobalt dinitrogen complexes [{(EP3Ph)Co(μ-N2)}2Mg(THF)4], with triphos ligand scaffolds (EP3Ph, E = N or CMe), were prepared via two electron reductions of the Co(i) precursors [CoCl(EP3Ph)]. Both complexes showed high degrees of N2 activation owing to the formation of a rare M-NN-Mg-NN-M bridging-magnesium core. These systems showed further N2 functionalisation reactivity by silylation, forming silyldiazenido complexes [(EP3Ph)Co(NNSiMe3)].
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Affiliation(s)
- Samantha L Apps
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 0BZ, UK.
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8
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Syntheses and Catalytic Hydrogenation Performance of Cationic Bis(phosphine) Cobalt(I) Diene and Arene Compounds. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201903766] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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9
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Zhong H, Friedfeld MR, Chirik PJ. Syntheses and Catalytic Hydrogenation Performance of Cationic Bis(phosphine) Cobalt(I) Diene and Arene Compounds. Angew Chem Int Ed Engl 2019; 58:9194-9198. [DOI: 10.1002/anie.201903766] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Indexed: 12/23/2022]
Affiliation(s)
- Hongyu Zhong
- Department of Chemistry Princeton University Frick Laboratory 292 Princeton NJ 08544 USA
| | - Max R. Friedfeld
- Department of Chemistry Princeton University Frick Laboratory 292 Princeton NJ 08544 USA
| | - Paul J. Chirik
- Department of Chemistry Princeton University Frick Laboratory 292 Princeton NJ 08544 USA
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Richers CP, Bertke JA, Rauchfuss TB. Syntheses of transition metal methoxysiloxides. Dalton Trans 2017; 46:8756-8762. [PMID: 28138664 DOI: 10.1039/c6dt04205h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The paper describes three methods for the preparation of methoxysiloxide complexes, a rare class of complexes of relevance to room temperature vulcanization (RTV) of polysiloxanes.
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Affiliation(s)
- Casseday P. Richers
- School of Chemical Sciences
- University of Illinois at Urbana-Champaign
- Urbana
- USA
| | - Jeffery A. Bertke
- School of Chemical Sciences
- University of Illinois at Urbana-Champaign
- Urbana
- USA
| | - Thomas B. Rauchfuss
- School of Chemical Sciences
- University of Illinois at Urbana-Champaign
- Urbana
- USA
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11
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Fischer PJ, Weberg AB, Bohrmann TD, Xu H, Young VG. Group VI metal complexes of tris(diphenylphosphinomethyl)phenylborate: modulation of ligand donation via coordination of M(CO)3 units at the borate phenyl substituent. Dalton Trans 2015; 44:3737-44. [PMID: 25604963 DOI: 10.1039/c4dt03857f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
A series of d(6) metal complexes of tris(diphenylphosphinomethyl)phenylborate ([PhB(CH2PPh2)3](-), PhBP3), including [Et4N][M(CO)3(PhBP3)] (M = Cr, Mo, W), inaugural group VI metal tris(phosphino)borate complexes, and zwitterionic Mn(CO)3(PhBP3) have been synthesized and fully characterized. An analysis of IR ν(CO) data for [Et4N][M(CO)3(PhBP3)] indicates that PhBP3 is significantly less strongly donating than Tp towards zerovalent M(CO)3 fragments; PhBP3 does not function as a strongly donating scorpionate in this system as its does towards cationic metal fragments suggesting that PhBP3 may not function as an effective surrogate of hydrotris(1-pyrazolyl)borate towards zerovalent metals. While the metal centers of [Et4N][M(CO)3(PhBP3)] are very likely still more electron-rich than those of M(CO)3(triphos), the anions of [Et4N][M(CO)3(PhBP3)] do not provide robust oxidative addition products analogous to those of M(CO)3(triphos). A new bi-functional role for PhBP3 was investigated via the synthesis of seven structurally characterized bimetallics in which zerovalent M(CO)3 and monovalent [Mn(CO)3](+) fragments bind the three phosphine atoms and the borate phenyl substituent. IR ν(CO) data support modest attenuation of PhBP3 donor ability at phosphorus upon η(6)-phenyl substituent binding, representing a new inductive strategy for tuning tris(phosphino)phenylborate donation at the κ(3)-phosphine-bound metal fragment.
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Affiliation(s)
- Paul J Fischer
- Department of Chemistry, Macalester College, 1600 Grand Avenue, Saint Paul, Minnesota 55105, USA.
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12
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Rose MJ, Bellone DE, Di Bilio AJ, Gray HB. Spectroscopic and magnetic properties of an iodo Co(I) tripodal phosphine complex. Dalton Trans 2012; 41:11788-97. [PMID: 22903546 DOI: 10.1039/c2dt31229h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reaction of the tripodal phosphine ligand 1,1,1-tris((diphenylphosphino)phenyl)ethane (PhP3) with CoI(2) spontaneously generates a one-electron reduced complex, [(PhP3)Co(I)(I)] (1). The crystal structure of 1 reveals a distorted tetrahedral environment, with an apical Co-I bond distance of ~2.52 Å. Co(II/I) redox occurs at an unusually high potential (+0.38 V vs. SCE). The electronic absorption spectrum of 1 exhibits an MLCT peak at 320 nm (ε = 8790 M(-1) cm(-1)) and a d-d feature at 850 nm (ε = 840 M(-1) cm(-1)). Two more d-d bands are observed in the NIR region, 8650 (ε = 450) and 7950 cm(-1) (ε = 430 M(-1) cm(-1)). Temperature dependent magnetic measurements (SQUID) on 1 (solid state, 20-300 K) give μ(eff) = 2.99(6) μ(B), consistent with an S = 1 ground state. Magnetic susceptibilities below 20 K are consistent with a zero field splitting (zfs) |D| = 8 cm(-1). DFT calculations also support a spin-triplet ground state for 1, as optimized (6-31G*/PW91) geometries (S = 1) closely match the X-ray structure. EPR measurements performed in parallel mode (X-band; 0-15,000 G, 15 K) on polycrystalline 1 or frozen solutions of 1 (THF/toluene) exhibit a feature at g≈ 4 that arises from a (Δm = 2) transition within the M(S) = <+1,-1> manifold. Below 10 K, the EPR signal decreases significantly, consistent with a solution zfs parameter (|D|≈ 8 cm(-1)) similar to that obtained from SQUID measurements. Our work provides an EPR signature for high-spin Co(I) in trigonal ligation.
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Affiliation(s)
- Michael J Rose
- Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA
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Park JH, Chang KM, Chung YK. Catalytic Pauson–Khand-type reactions and related carbonylative cycloaddition reactions. Coord Chem Rev 2009. [DOI: 10.1016/j.ccr.2009.08.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Park JH, Chung YK. Cobalt–rhodium heterobimetallic nanoparticle-catalyzed reactions. Dalton Trans 2008:2369-78. [DOI: 10.1039/b718609f] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Schenk WA, Beucke T, Burzlaff N, Klüglein M, Stemmler M. Ruthenium complexes of thiocinnamaldehydes: synthesis, structure, and [4+2]-cycloaddition reactions. Chemistry 2007; 12:4821-34. [PMID: 16642522 DOI: 10.1002/chem.200501430] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Ruthenium hydrogensulfido complexes [CpRu(P-P)(SH)] ((P-P)=Ph(2)PCH(2)PPh(2) (dppm), Ph(2)PC(2)H(4)PPh(2) (dppe)) were obtained from the corresponding chloro complexes by Cl/SH exchange. Condensation with a range of cinnamaldehydes gave thiocinnamaldehyde complexes [CpRu(P-P)(S=CH-CR(2)=CHR(1))]PF(6) (R(1)=C(6)H(4)X, R(2)=H, Me, X=H, OMe, NMe(2), Cl, NO(2)) as highly-colored crystalline compounds. The thiocinnamaldehyde complexes undergo [4+2]-cycloaddition reactions with vinyl ethers CH(2)=CHOR(3) (R(3)=Et, Bu) and styrenes H(2)C=CHC(6)H(4)Y (Y=H, Me, OMe, Cl, Br, NO(2)) to give complexes of 2,4,5-trisubstituted 3,4-dihydro-2H-thiopyrans as mixtures of two diastereoisomers. The rate of addition of para-substituted styrenes H(2)C=CHC(6)H(4)Y to [CpRu(dppm)(S=CH-CH=CHPh)]PF(6) increases in the series Y=NO(2), Br, Cl, H, Me, OMe, indicating that the cycloaddition is dominated by the HOMO(dienophile)-LUMO(diene) interaction. The strained dienophiles norbornadiene and norbornene also add, giving ruthenium complexes of 3-thia-tricyclo[6.2.1.0(2,7)]undeca-4,9-dienes and 3-thia-tricyclo[6.2.1.0(2,7)]undec-4-enes, respectively. Addition reactions with acrolein, methacrolein, methyl vinyl ketone, acrylic ester, or ethyl propiolate finally yielded ruthenium complexes of 3,4-disubstituted 3,4-dihydro-2H-thiopyrans and 4H-thiopyrans, respectively.
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Affiliation(s)
- Wolfdieter A Schenk
- Institut für Anorganische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
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Abstract
Five membered carbocycles are important building blocks for many biologically active molecules. Moreover, substituted cyclopentenones (e.g. cyclopentenone prostaglandins) exhibit characteristic biological activity. The efficiency and atom economy of the Pauson-Khand reaction render this process potentially one of the most attractive methods for the synthesis of such compounds. Although it was discovered in its intermolecular form, the scope of the intermolecular Pauson-Khand reaction has always been limited by the poor reactivity and selectivity of the alkene component. The past decade, especially the last three years, has seen concerted efforts to broaden the scope of this reaction. In this overview, we provide a comprehensive and critical coverage of the intermolecular Pauson-Khand reaction based on the reactivity characteristics of different classes of alkenes and a rationalization of successes and misfortunes in this area.
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Affiliation(s)
- Susan E Gibson
- Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AY, UK.
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Lin CY, Tsai CF, Chen HJ, Hung CH, Yu RC, Kuo PC, Lee HM, Huang JH. Insertion, Reduction, and Carbon–Carbon Coupling Induced by Monomeric Aluminum Hydride Compounds Bearing Substituted Pyrrolyl Ligands. Chemistry 2006; 12:3067-73. [PMID: 16429470 DOI: 10.1002/chem.200500989] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A monomeric aluminum hydride complex bearing substituted pyrrolyl ligands, AlH[C(4)H(3)N(CH(2)NMe(2))-2](2) (1), was synthesized and structurally characterized. To further confirm the presence of Al--H bonds, the compound AlD[C(4)H(3)N(CH(2)NMe(2))-2](2) ([D]1) was synthesized by reacting LiAlD(4) with [C(4)H(4)N(CH(2)NMe(2))-2]. Compound 1 and [D]1 react with phenyl isothiocyanate yielding Al[C(4)H(3)N(CH(2)NMe(2))-2](2)[eta(3)-SCHNPh] (2) and Al[C(4)H(3)N(CH(2)NMe(2))-2](2)[eta(3)-SCDNPh] ([D]2) by insertion. The reactions of 1 with 9-fluorenone and benzophenone generated the unusual aluminum alkoxide complexes 3 and 4, respectively, through intramolecular proton abstraction and C-C coupling. A mechanistic study shows that 9-fluorenone coordinates to [D]1 and releases one equivalent of HD followed by C-C coupling and hydride transfer to yield the final product. Reduction of benzil with 1 affords aluminum enediolate complex 5 in moderate yield. Mechanistic studies also showed that the benzil was inserted into the aluminum hydride bond of [D]1 through hydroalumination followed by proton transfer to generate the final product [D]5. All new complexes have been characterized by (1)H and (13)C NMR spectroscopy and X-ray crystallography.
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Affiliation(s)
- Che-Yu Lin
- Department of Chemistry, National Changhua University of Education, Changhua, Taiwan
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Park KH, Jung IG, Chung YK. A Pauson−Khand-Type Reaction between Alkynes and Olefinic Aldehydes Catalyzed by Rhodium/Cobalt Heterobimetallic Nanoparticles: An Olefinic Aldehyde as an Olefin and CO Source. Org Lett 2004; 6:1183-6. [PMID: 15040753 DOI: 10.1021/ol049765s] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Co/Rh (Co:Rh = 2:2) heterobimetallic nanoparticles derived from Co(2)Rh(2)(CO)(12) react with alkynes and alpha,beta-unsaturated aldehydes such as acrolein, crotonaldehyde, and cinnamic aldehyde and release products resulting from [2 + 2 + 1]cycloaddition of alkyne, carbon monoxide, and alkene. alpha,beta-Unsaturated aldehydes act as a CO and alkene source. These reactions produce 2-substituted cyclopentenones.
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Affiliation(s)
- Kang Hyun Park
- School of Chemistry, Seoul National University, Seoul 151-747, Korea
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Winterhalter U, Zsolnai L, Kircher P, Heinze K, Huttner G. Reductive Activation of Tripod Cobalt Compounds: Oxidative Addition of H−H, P−H, and Sn−H Functions. Eur J Inorg Chem 2001. [DOI: 10.1002/1099-0682(20011)2001:1<89::aid-ejic89>3.0.co;2-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Rupp R, Huttner G, Kircher P, Soltek R, Büchner M. Coordination Compounds oftripodCoII andtripodCoI − Selective Substitution and Redox Behaviour. Eur J Inorg Chem 2000. [DOI: 10.1002/1099-0682(200008)2000:8<1745::aid-ejic1745>3.0.co;2-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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