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Thierer LM, Brooks SH, Weberg AB, Cui P, Zhang S, Gau MR, Manor BC, Carroll PJ, Tomson NC. Macrocycle-Induced Modulation of Internuclear Interactions in Homobimetallic Complexes. Inorg Chem 2022; 61:6263-6280. [PMID: 35422117 PMCID: PMC9252315 DOI: 10.1021/acs.inorgchem.2c00522] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A synthetic route has been developed for a series of 3d homobimetallic complexes of Mn, Fe, Co, Ni, and Cu using three different pyridyldiimine and pyridyldialdimine macrocyclic ligands with ring sizes of 18, 20, and 22 atoms. Crystallographic analyses indicate that while the distances between the metals can be modulated by the size of the macrocycle pocket, the flexibility in the alkyl linkers used to construct the macrocycles enables the ligand to adjust the orientation of the PD(A)I fragments in response to the geometry of the [M2(μ-Cl)2]2+ core, particularly with respect to Jahn-Teller distortions. Analyses by UV-vis spectroscopy and SQUID magnetometry revealed deviations in the properties [M2(μ-Cl)2]2+-containing complexes bound by standard mononucleating ligands, highlighting the ability of macrocycles to use ring size to control the magnetic interactions of pseudo-octahedral, high-spin metal centers.
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Affiliation(s)
- Laura M. Thierer
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Sam H. Brooks
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Alexander B. Weberg
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Peng Cui
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Shaoguang Zhang
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Michael R. Gau
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Brian C. Manor
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Patrick J. Carroll
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Neil C. Tomson
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States
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Verhoeven DGA, Albrecht M. Modular O- vs. N-coordination of pyridylidene amide ligands to iron determines activity in alcohol oxidation catalysis. Dalton Trans 2020; 49:17674-17682. [PMID: 33232405 DOI: 10.1039/d0dt02818e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A family of polydentate pyridine-substituted pyridylidene amide (PYA) complexes bound to iron(ii) was developed. The variation of the coordination set from NN-bidentate PYA to tridentate pincer-type pyPYA2 systems (pyPYA2 = 2,6-bis(PYA)pyridine) had a large influence on the binding mode to iron(ii), including a change from the N- to rare O-coordination of the PYA site and a concomitant shift of the predominant ligand resonance structure. These binding mode variations invoke changes in the reactivity of the complexes, which were probed in the peroxide-mediated oxidation of 1-phenylethanol to acetophenone. A comparison with uncomplexed FeCl2 indicated that bidentate NN coordination is unstable and presumably leads to the dissociation of FeCl2. In contrast, the tridentate ligand binding is robust. Remarkably, the tridentate PYA pincer coordination inhibits catalytic activity in the NNN binding mode, while the ONO coordination greatly enhances catalytic performance. Under optimized conditions, the bis-ligated ONO pincer iron complex [Fe(pyPYA2)2][2PF6] reaches full conversion within one hour (0.5 mol% catalyst loading) and under dilute conditions turnover numbers over 20 000 (0.005 mol% catalyst loading).
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Affiliation(s)
- Dide G A Verhoeven
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
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Eaton MC, Knight BJ, Brahmi R, Ferreira RB, Catalano VJ, Rheingold AL, Ghiviriga I, Murray LJ. Synthetic Factors Governing Access to Tris(β-diketimine) Cyclophanes versus Tripodal Tri-β-aminoenones. J Org Chem 2020; 85:13579-13588. [PMID: 33107735 DOI: 10.1021/acs.joc.0c01708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tris(β-diketimine) cyclophanes are an important ligand class for investigating cooperative multimetallic interactions of bioinorganic clusters. Discussed herein are the synthetic factors governing access to tris(β-diketimine) cyclophanes versus tripodal tri-β-aminoenones. Cyclophanes bearing Me, Et, and MeO cap substituents and β-Me, Et, or Ph arm substituents are obtained, and a modified condensation method produced α-Me β-Me cyclophane. These operationally simple procedures produce the ligands in gram quantities and in 22-94% yields.
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Affiliation(s)
- Mary C Eaton
- Center for Catalysis and Florida Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, 214 Leigh Hall, P.O. Box 117200, Gainesville, Florida 32611, United States
| | - Brian J Knight
- Center for Catalysis and Florida Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, 214 Leigh Hall, P.O. Box 117200, Gainesville, Florida 32611, United States
| | - Robin Brahmi
- Center for Catalysis and Florida Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, 214 Leigh Hall, P.O. Box 117200, Gainesville, Florida 32611, United States
| | - Ricardo B Ferreira
- Center for Catalysis and Florida Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, 214 Leigh Hall, P.O. Box 117200, Gainesville, Florida 32611, United States
| | - Vincent J Catalano
- Department of Chemistry, University of Nevada, Reno, Nevada 89557, United States
| | - Arnold L Rheingold
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, San Diego, California 92093, United States
| | - Ion Ghiviriga
- Department of Chemistry, University of Florida, 214 Leigh Hall, P.O. Box 117200, Gainesville, Florida 32611, United States
| | - Leslie J Murray
- Center for Catalysis and Florida Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, 214 Leigh Hall, P.O. Box 117200, Gainesville, Florida 32611, United States
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Melle P, Ségaud N, Albrecht M. Ambidentate bonding and electrochemical implications of pincer-type pyridylidene amide ligands in complexes of nickel, cobalt and zinc. Dalton Trans 2020; 49:12662-12673. [PMID: 32959829 DOI: 10.1039/d0dt02482a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Pincer-type tridentate pyridyl bis(pyridylidene amide) (pyPYA2) ligand systems were coordinated to the Earth-abundant first row transition metals nickel, cobalt and zinc. A one-pot synthesis in water/ethanol afforded octahedral homoleptic bis-PYA complexes, [M(pyPYA2)2](PF6)2, whereas five-coordinate mono-PYA dichloride complexes, [M(pyPYA2)Cl2], were obtained upon slow addition of the ligand to the metal chlorides in DMF. Electrochemical measurements further revealed a facile oxidation of the metal centers from Ni2+ to Ni4+ and Co2+ to Co3+, respectively, while the Zn2+ system was redox inactive. These experiments further allowed for quantification of the much stronger electron donor properties of neutral N,N,N-tridentate pyPYA2 pincer ligands as compared to terpy. Remarkably, ortho-PYA pincer ligands feature amide coordination to the metal center via oxygen or nitrogen. This ambidentate ligand binding constitutes another mode of donor flexibility of the PYA ligand system, complementing the resonance structure dynamics established previously. NMR spectroscopic and MS analysis reveal that the meta-PYA ligand undergoes selective deuteration when coordinated to cobalt. This reactivity suggests the potential of this ligand as a transient proton reservoir for HX bond activation and, moreover, indicates the relevance of several resonance structures and therefore supports the notion that meta-PYA ligands are mesoionic.
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Affiliation(s)
- Philipp Melle
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
| | - Nathalie Ségaud
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
| | - Martin Albrecht
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
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Guillet GL, Arpin KY, Boltin AM, Gordon JB, Rave JA, Hillesheim PC. Synthesis and Characterization of a Linear Triiron(II) Extended Metal Atom Chain Complex with Fe–Fe Bonds. Inorg Chem 2020; 59:11238-11243. [DOI: 10.1021/acs.inorgchem.0c01625] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gary L. Guillet
- Department of Chemistry and Biochemistry, Georgia Southern University, 11935 Abercorn Street, Savannah, Georgia 31419, United States
| | - Kathleen Y. Arpin
- Department of Chemistry and Biochemistry, Georgia Southern University, 11935 Abercorn Street, Savannah, Georgia 31419, United States
| | - Alan M. Boltin
- Department of Chemistry and Biochemistry, Georgia Southern University, 11935 Abercorn Street, Savannah, Georgia 31419, United States
| | - Jesse B. Gordon
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Justin A. Rave
- Department of Chemistry and Biochemistry, Georgia Southern University, 11935 Abercorn Street, Savannah, Georgia 31419, United States
| | - Patrick C. Hillesheim
- Department of Chemistry and Physics, Ave Maria University, 5050 Ave Maria Boulevard, Ave Maria, Florida 34142, United States
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Sánchez RH, Betley TA. Thermally Persistent High-Spin Ground States in Octahedral Iron Clusters. J Am Chem Soc 2018; 140:16792-16806. [PMID: 30403845 DOI: 10.1021/jacs.8b10181] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chemical oxidation and reduction of the all-ferrous (HL)2Fe6 in THF affords isostructural, coordinatively unsaturated clusters of the type [(HL)2Fe6] n: [(HL)2Fe6][BArF24] (1, n = +1; where [BArF24]- = tetrakis[(3,5-trifluoromethyl)phenyl]borate), [Bu4N][(HL)2Fe6] (2a, n = -1), [P][(HL)2Fe6] (2b, n = -1; where [P]+ = tributyl(1,3-dioxolan-2-ylmethyl)phosphonium), and [Bu4N]2[(HL)2Fe6] (3, n = -2). Each member of the redox-transfer series was characterized by zero-field 57Fe Mössbauer spectroscopy, near-infrared spectroscopy, single-crystal X-ray crystallography, and magnetometry. Redox-directed trends are observed when comparing the structural metrics within the [Fe6] core. The metal octahedron [Fe6] decreases marginally in volume as the molecular reduction state increases as gauged by the Fe-Feavg distance varying from 2.608(11) Å ( n = +1) to 2.573(3) ( n = -2). In contrast, the mean Fe-N distances and ∠Fe-N-Fe angles correlate linearly with the [Fe6] oxidation level, or alternatively, the changes observed within the local Fe-N4 coordination planes vary linearly with the aggregate spin ground state. In general, as the spin ground state ( S) increases, the Fe-N(H)avg distances also increase. The structural metric perturbations within the [Fe6] core and measured spin ground states were rationalized extending the previously proposed molecular orbital diagram derived for (HL)2Fe6. Chemical reduction of the (HL)2Fe6 cluster results in an abrupt increase in spin ground state from S = 6 for the all-ferrous cluster, to S = 19/2 in the monoanionic 2b and S = 11 for the dianionic 3. The observation of asymmetric intervalence charge transfer bands in 3 provides further evidence of the fully delocalized ground state observed by 57Fe Mössbauer spectroscopy for all species examined (1-3). For each of the clusters examined within the electron-transfer series, the observed spin ground states thermally persist to 300 K. In particular, the S = 11 in dianionic 3 and S = 19/2 in the monoanionic 2b represent the highest spin ground states isolated up to room temperature known to date. The increase in spin ground state results from population of the antibonding orbital band comprised of the Fe-N σ* interactions. As such, the thermally persistent ground states arise from population of the resultant single spin manifolds in accordance with Hund's rules. The large spin ground states, indicative of strong ferromagnetic electronic alignment of the valence electrons, result from strong direct exchange electronic coupling mediated by Fe-Fe orbital overlap within the [Fe6] cores, equivalent to a strong double exchange magnetic coupling B for 3 that was calculated to be 309 cm-1.
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Affiliation(s)
- Raúl Hernández Sánchez
- Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States
| | - Theodore A Betley
- Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States
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Wang VCC, Maji S, Chen PPY, Lee HK, Yu SSF, Chan SI. Alkane Oxidation: Methane Monooxygenases, Related Enzymes, and Their Biomimetics. Chem Rev 2017; 117:8574-8621. [PMID: 28206744 DOI: 10.1021/acs.chemrev.6b00624] [Citation(s) in RCA: 249] [Impact Index Per Article: 35.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Methane monooxygenases (MMOs) mediate the facile conversion of methane into methanol in methanotrophic bacteria with high efficiency under ambient conditions. Because the selective oxidation of methane is extremely challenging, there is considerable interest in understanding how these enzymes carry out this difficult chemistry. The impetus of these efforts is to learn from the microbes to develop a biomimetic catalyst to accomplish the same chemical transformation. Here, we review the progress made over the past two to three decades toward delineating the structures and functions of the catalytic sites in two MMOs: soluble methane monooxygenase (sMMO) and particulate methane monooxygenase (pMMO). sMMO is a water-soluble three-component protein complex consisting of a hydroxylase with a nonheme diiron catalytic site; pMMO is a membrane-bound metalloenzyme with a unique tricopper cluster as the site of hydroxylation. The metal cluster in each of these MMOs harnesses O2 to functionalize the C-H bond using different chemistry. We highlight some of the common basic principles that they share. Finally, the development of functional models of the catalytic sites of MMOs is described. These efforts have culminated in the first successful biomimetic catalyst capable of efficient methane oxidation without overoxidation at room temperature.
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Affiliation(s)
- Vincent C-C Wang
- Institute of Chemistry, Academia Sinica , 128, Section 2, Academia Road, Nankang, Taipei 11529, Taiwan
| | - Suman Maji
- School of Chemical Engineering and Physical Sciences, Lovely Professional University , Jalandhar-Delhi G. T. Road (NH-1), Phagwara, Punjab India 144411
| | - Peter P-Y Chen
- Department of Chemistry, National Chung Hsing University , 250 Kuo Kuang Road, Taichung 402, Taiwan
| | - Hung Kay Lee
- Department of Chemistry, The Chinese University of Hong Kong , Shatin, New Territories, Hong Kong
| | - Steve S-F Yu
- Institute of Chemistry, Academia Sinica , 128, Section 2, Academia Road, Nankang, Taipei 11529, Taiwan
| | - Sunney I Chan
- Institute of Chemistry, Academia Sinica , 128, Section 2, Academia Road, Nankang, Taipei 11529, Taiwan.,Department of Chemistry, National Taiwan University , No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.,Noyes Laboratory, 127-72, California Institute of Technology , 1200 East California Boulevard, Pasadena, California 91125, United States
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Zhang Q, Bell-Taylor A, Bronston FM, Gorden JD, Goldsmith CR. Aldehyde Deformylation and Catalytic C–H Activation Resulting from a Shared Cobalt(II) Precursor. Inorg Chem 2016; 56:773-782. [DOI: 10.1021/acs.inorgchem.6b02127] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Qiao Zhang
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Angela Bell-Taylor
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Fraser M. Bronston
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - John D. Gorden
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Christian R. Goldsmith
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
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Huang DW, Liu YH, Peng SM, Liu ST. Dinickel complexes with anthyridine-based ligands. Dalton Trans 2016; 45:8265-71. [PMID: 27103235 DOI: 10.1039/c6dt00567e] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Two new dinickel complexes with anthyridine-based ligands, 5-phenyl-2,8-bis(2-pyridinyl)-1,9,10-anthyridine () and 5-phenyl-2,8-bis(6'-bipyridinyl)-1,9,10-anthyridine (), are reported. Complexation of Ni(OAc)2 with and in trifluoroacetic acid provided the corresponding dinickel complexes [{Ni2()(H2O)6(CF3COO)2}(CF3COO)2] () and [Ni2()(CF3COO)4(H2O)] (), respectively. Both complexes were characterized by spectroscopic methods and further confirmed by X-ray crystallography. Structural analyses of and revealed the NiNi distances in the complexes to be 5.4086(6) and 5.0138(7) Å, respectively. The catalytic activities of complexes and toward the reduction of carboxylic acids were evaluated. It appears that complex shows a good catalytic activity toward the reduction of carboxylates into the corresponding alcohols by diphenylsilane.
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Affiliation(s)
- Da-Wei Huang
- Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.
| | - Yi-Hung Liu
- Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.
| | - Shie-Ming Peng
- Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.
| | - Shiuh-Tzung Liu
- Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.
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Kumar P, Gupta R. The wonderful world of pyridine-2,6-dicarboxamide based scaffolds. Dalton Trans 2016; 45:18769-18783. [DOI: 10.1039/c6dt03578g] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This perspective focusses on a variety of scaffolds based on a pyridine-2,6-dicarboxamide fragment and their noteworthy roles in coordination chemistry, biomimetic studies, catalysis, and sensing.
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Affiliation(s)
- Pramod Kumar
- Department of Chemistry
- University of Delhi
- Delhi-110007
- India
| | - Rajeev Gupta
- Department of Chemistry
- University of Delhi
- Delhi-110007
- India
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Ermert DM, Murray LJ. Insights into small molecule activation by multinuclear first-row transition metal cyclophanates. Dalton Trans 2016; 45:14499-507. [DOI: 10.1039/c6dt01857b] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The rational design of trimetallic transition metal clusters supported by a trinucleating cyclophane ligand, L3−, and the reactivities of these complexes with dinitrogen and carbon dioxide are discussed.
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Affiliation(s)
- David M. Ermert
- Center for Catalysis
- Department of Chemistry
- University of Florida
- Gainesville
- USA
| | - Leslie J. Murray
- Center for Catalysis
- Department of Chemistry
- University of Florida
- Gainesville
- USA
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