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Cordeiro LL, Dmitrenko O, Yap GPA, Riordan CG. Synthesis and Reactivity Studies of a Series of Nickel(II) Arylchalcogenolates. Inorg Chem 2021; 60:6327-6338. [PMID: 33851821 DOI: 10.1021/acs.inorgchem.1c00066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Two series of high-spin nickel complexes, [TpPh,Me]Ni(EAr) (E = O, Se, Te; Ar = C6H5) and [TpPh,Me]Ni(SeC6H4-4-X) (X = H, Cl, Me, OMe), were prepared by metathetical reaction of the nickel(II) halide precursor with sodium salts of the corresponding chalcogen, NaEAr. X-ray crystallographic characterization and spectroscopic studies have established the geometric and electronic structures of these complexes. The observed spectroscopic and structural characteristics reveal distinct trends in accordance with the variation of the identity of the arylchalcogenolate and para substituent. Reaction of the [TpPh,Me]Ni(EAr) complexes with methyl iodide proceeded readily, producing the corresponding methylarylchalcogen and [TpPh,Me]NiI. A kinetic and computational analysis of the reaction of [TpPh,Me]Ni(SeC6H5) with MeI supports that the electrophilic alkylation reactions occur via an associative mechanism via a classical SN2 transition state.
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Affiliation(s)
- Lauren L Cordeiro
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Olga Dmitrenko
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Glenn P A Yap
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Charles G Riordan
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
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2
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Narwane M, Chang YL, Ching WM, Tsai ML, Hsu SC. Investigation on the coordination behaviors of tris(2-pyridyl)pyrazolyl borates iron(II) complexes. Inorganica Chim Acta 2019. [DOI: 10.1016/j.ica.2019.118966] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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3
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Burrows JE, Paulson MQ, Altman ER, Vukovic I, Machonkin TE. The role of halogen substituents and substrate pK a in defining the substrate specificity of 2,6-dichlorohydroquinone 1,2-dioxygenase (PcpA). J Biol Inorg Chem 2019; 24:575-589. [PMID: 31089822 DOI: 10.1007/s00775-019-01663-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 05/07/2019] [Indexed: 12/01/2022]
Abstract
2,6-Dichlorohydroquinone 1,2-dioxygenase (PcpA) is a non-heme Fe(II) enzyme that is specific for ortho-dihalohydroquinones. Here we deconvolute the role of halogen polarizability vs. substrate pKa in defining this specificity, and show how substrate binding compares to the structurally homologous catechol extradiol dioxygenases. The substrates 2,6-dichloro- and 2,6-dibromohydroquinone (polarizable halogens, pKa1 = 7.3), 2,6-difluorohydroquinone (nonpolarizable halogens, pKa1 = 7.5), and 2-chloro-6-methylhydroquinone (polarizable halogen, pKa1 = 9.0) were examined through spectrophotometric titrations and steady-state kinetics. The results show that binding of the substrates to the enzyme decreased [Formula: see text] by about 0.5, except for 2,6-difluorohydroquinone, which showed no change. Additionally, the Kd values of 2,6-dichloro- and 2,6-dibromohydroquinone are about equal to their respective [Formula: see text]. For comparison, with catechol 2,3-dioxygenase (XylE), the substrates 4-methyl- and 3-bromocatechol are bound to the enzyme exclusively in the monoanion form over a wide pH range, indicating a [Formula: see text] of at least - 2.9 and - 1.2, respectively. The steady-state kinetic studies showed that 2,6-difluorohydroquinone is a poor substrate, with [Formula: see text] approximately 40-fold lower and [Formula: see text] 20-fold higher than 2,6-dichlorohydroquinone, despite its similar pKa1. Likewise, the pH dependence of [Formula: see text] for 2-chloro-6-methylhydroquinone is nearly identical to that of 2,6-dichlorohydroquinone, despite its very different pKa1. These results show that (1) it is clearly the halogen polarizability and not the lower substrate pKa that determines the substrate specificity of PcpA, and (2) that PcpA, unlike the catechol extradiol dioxygenases, lacks an active site base that assists with substrate deprotonation, highlighting a key functional difference in what are otherwise similar active sites that defines their different reactivity.
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Affiliation(s)
- Julia E Burrows
- Department of Chemistry, Whitman College, 345 Boyer Ave, Walla Walla, WA, 99362, USA
| | - Monica Q Paulson
- Department of Chemistry, Whitman College, 345 Boyer Ave, Walla Walla, WA, 99362, USA
| | - Emma R Altman
- Department of Chemistry, Whitman College, 345 Boyer Ave, Walla Walla, WA, 99362, USA
| | - Ivana Vukovic
- Department of Chemistry, Whitman College, 345 Boyer Ave, Walla Walla, WA, 99362, USA
| | - Timothy E Machonkin
- Department of Chemistry, Whitman College, 345 Boyer Ave, Walla Walla, WA, 99362, USA.
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Wang P, Yap GP, Riordan CG. Synthesis, characterization and O2 reactivity of a bioinspired cobalt(II)-catecholate complex. Inorganica Chim Acta 2019. [DOI: 10.1016/j.ica.2019.01.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Aryaeifar M, Amiri Rudbari H, Bruno G. A close insight into the nature of intra- and intermolecular interactions in new Cu(II) Schiff base complexes derived from halogenated salicylaldehydes and allylamine: Theoretical and crystallographic studies. Polyhedron 2018. [DOI: 10.1016/j.poly.2018.08.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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van Dijkman TF, de Bruijn HM, Brevé TG, van Meijeren B, Siegler MA, Bouwman E. Extremely bulky copper(i) complexes of [HB(3,5-{1-naphthyl} 2pz) 3] - and [HB(3,5-{2-naphthyl} 2pz) 3] - and their self-assembly on graphene. Dalton Trans 2017; 46:6433-6446. [PMID: 28470290 DOI: 10.1039/c6dt04851j] [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 synthesis and characterization, using NMR (1H and 13C), infrared spectroscopy, and X-ray crystallography, of the ethene and carbon monoxide copper(i) complexes of hydridotris(3,5-diphenylpyrazol-1-yl)borate ([TpPh2]-) and the two new ligands hydridotris(3,5-bis(1-naphthyl)pyrazol-1-yl)borate ([Tp(1Nt)2]-) and hydridotris(3,5-bis-(2-naphthyl)pyrazol-1-yl)borate ([Tp(2Nt)2]-) are described. X-ray crystal structures are presented of [Cu(TpPh2)(C2H4)] and [Cu(Tp(2Nt)2)(C2H4)]. The compound [Cu(TpPh2)(C2H4)] features interactions between the protons of the ethene ligand and the π-electron clouds of the phenyl substituents that make up the binding pocket surrounding the copper(i) center. These dipolar interactions result in strongly upfield shifted signals of the ethene protons in 1H-NMR. [Cu(Tp(1Nt)2)(CO)] and [Cu(Tp(2Nt)2)(CO)] were examined using infrared spectroscopy and were found to have CO stretching vibrations at 2076 and 2080 cm-1 respectively. The copper(i) carbonyl complexes form self-assembled monolayers when drop cast onto HOPG and thin multilayers of a few nanometers thickness when dip coated onto graphene. General macroscopic trends such as the different tendencies to crystallize observed in the complexes of the two naphthyl-substituted ligands appear to extend well to the nanoscale where a well-organized monolayer could be observed of [Cu(Tp(2Nt)2)(CO)].
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Affiliation(s)
- Thomas F van Dijkman
- Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA, Leiden, The Netherlands.
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Joy J, Jemmis ED. Contrasting Behavior of the Z Bonds in X-Z···Y Weak Interactions: Z = Main Group Elements Versus the Transition Metals. Inorg Chem 2017; 56:1132-1143. [PMID: 28075570 DOI: 10.1021/acs.inorgchem.6b02073] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In contrast to the increasing family of weak intermolecular interactions in main-group compounds (X-Z···Y, Z = main-group elements), an analysis of the Cambridge Structural Database indicates that electron-saturated (18-electron) transition-metal complexes show reluctance toward weak M bond formation (X-M···Y, M = transition metal). In particular, weak M bonds involving electron-saturated (18-electron) complexes of transition metals with partially filled d-orbitals are not found. We propose that the nature of valence electron density distribution in transition-metal complexes is the primary reason for this reluctance. A survey of the interaction of selected electron-saturated transition-metal complexes with electron-rich molecules (Y) demonstrates the following: shielding the possible σ-hole on the metal center by the core electron density in 3d series, and enhanced electronegativity and relativistic effects in 4d and 5d series, hinders the formation of the M bond. A balance in all the destabilizing effects has been found in the 4d series due to its moderate polarizability and primogenic repulsion from inner core d-electrons. A changeover in the donor-acceptor nature of the metal center toward different types of incoming molecules is also unveiled here. The present study confirms the possibility of M bond as a new supramolecular force in designing the crystal structures of electron-saturated transition-metal complexes by invoking extreme ligand conditions.
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Affiliation(s)
- Jyothish Joy
- School of Chemistry, Indian Institute of Science Education and Research-Thiruvananthapuram , Kerala, Thiruvananthapuram 695016, India
| | - Eluvathingal D Jemmis
- Department of Inorganic and Physical Chemistry, Indian Institute of Science , Bangalore 560012, India
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Guo XK, Zhang LB, Wei D, Niu JL. Mechanistic insights into cobalt(ii/iii)-catalyzed C-H oxidation: a combined theoretical and experimental study. Chem Sci 2015; 6:7059-7071. [PMID: 29861945 PMCID: PMC5947531 DOI: 10.1039/c5sc01807b] [Citation(s) in RCA: 155] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 09/04/2015] [Indexed: 12/21/2022] Open
Abstract
Cobalt-mediated C-H functionalization has been the subject of extensive interest in synthetic chemistry, but the mechanisms of many of these reactions (such as the cobalt-catalyzed C-H oxidation) are poorly understood. In this paper, possible mechanisms including single electron transfer (SET) and the concerted metalation-deprotonation (CMD) pathways of the CoII/CoIII-catalyzed alkoxylation of C(sp2)-H bonds have been investigated for the first time using the DFT method. CoII(OAc)2 has been employed as an efficient catalyst in our previous experimental study, but the calculated results unexpectedly indicated that the intermolecular SET pathway with CoIII as the actual catalyst might be the most favorable pathway. To support this theoretical prediction, we have explored a series of Cp*CoIII(CO)I2 catalyzed C(sp2)-H bond alkoxylations, extending the application of cobalt-catalyzed functionalization of C-H bonds. Furthermore, kinetic isotope effect (KIE) data, electron paramagnetic resonance (EPR) data, and TEMPO inhibition experiments also support the SET mechanism in both the Co-catalyzed alkoxylation reactions. Thus, this work should support an understanding of the possible mechanisms of the CoII/CoIII-catalyzed C(sp2)-H functionalization, and also provide an example of the rational design of novel catalytic reactions guided by theoretical calculations.
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Affiliation(s)
- Xiao-Kang Guo
- The College of Chemistry and Molecular Engineering , Zhengzhou University , Zhengzhou , Henan Province 450001 , P. R. China . ;
| | - Lin-Bao Zhang
- The College of Chemistry and Molecular Engineering , Zhengzhou University , Zhengzhou , Henan Province 450001 , P. R. China . ;
| | - Donghui Wei
- The College of Chemistry and Molecular Engineering , Zhengzhou University , Zhengzhou , Henan Province 450001 , P. R. China . ;
| | - Jun-Long Niu
- The College of Chemistry and Molecular Engineering , Zhengzhou University , Zhengzhou , Henan Province 450001 , P. R. China . ;
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Schofield JA, Brennessel WW, Urnezius E, Rokhsana D, Boshart MD, Juers DH, Holland PL, Machonkin TE. Metal-Halogen Secondary Bonding in a 2,5-Dichlorohydroquinonate Cobalt(II) Complex: Insight into Substrate Coordination in the Chlorohydroquinone Dioxygenase PcpA. Eur J Inorg Chem 2015. [DOI: 10.1002/ejic.201500845] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Deb T, Anderson CM, Ma H, Petersen JL, Young VG, Jensen MP. Scorpionato Halide Complexes [(Tp
Ph,Me
)Ni–X] [X = Cl, Br, I; Tp
Ph,Me
= Hydrotris(3‐phenyl‐5‐methyl‐1‐pyrazolyl)borate]: Structures, Spectroscopy, and Pyrazole Adducts. Eur J Inorg Chem 2014. [DOI: 10.1002/ejic.201402897] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Tapash Deb
- Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701, U.S.A., http://www.ohio.edu/chemistry/faculty/jensen.php
| | - Caitlin M. Anderson
- Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701, U.S.A., http://www.ohio.edu/chemistry/faculty/jensen.php
| | - Huaibo Ma
- Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701, U.S.A., http://www.ohio.edu/chemistry/faculty/jensen.php
| | - Jeffrey L. Petersen
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, U.S.A
| | - Victor G. Young
- X‐ray Crystallographic Laboratory, Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, U.S.A
| | - Michael P. Jensen
- Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701, U.S.A., http://www.ohio.edu/chemistry/faculty/jensen.php
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Lang JM, Eisen JA, Zivkovic AM. The microbes we eat: abundance and taxonomy of microbes consumed in a day's worth of meals for three diet types. PeerJ 2014; 2:e659. [PMID: 25538865 PMCID: PMC4266855 DOI: 10.7717/peerj.659] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2014] [Accepted: 10/18/2014] [Indexed: 12/21/2022] Open
Abstract
Far more attention has been paid to the microbes in our feces than the microbes in our food. Research efforts dedicated to the microbes that we eat have historically been focused on a fairly narrow range of species, namely those which cause disease and those which are thought to confer some “probiotic” health benefit. Little is known about the effects of ingested microbial communities that are present in typical American diets, and even the basic questions of which microbes, how many of them, and how much they vary from diet to diet and meal to meal, have not been answered. We characterized the microbiota of three different dietary patterns in order to estimate: the average total amount of daily microbes ingested via food and beverages, and their composition in three daily meal plans representing three different dietary patterns. The three dietary patterns analyzed were: (1) the Average American (AMERICAN): focused on convenience foods, (2) USDA recommended (USDA): emphasizing fruits and vegetables, lean meat, dairy, and whole grains, and (3) Vegan (VEGAN): excluding all animal products. Meals were prepared in a home kitchen or purchased at restaurants and blended, followed by microbial analysis including aerobic, anaerobic, yeast and mold plate counts as well as 16S rRNA PCR survey analysis. Based on plate counts, the USDA meal plan had the highest total amount of microbes at 1.3 × 109 CFU per day, followed by the VEGAN meal plan and the AMERICAN meal plan at 6 × 106 and 1.4 × 106 CFU per day respectively. There was no significant difference in diversity among the three dietary patterns. Individual meals clustered based on taxonomic composition independent of dietary pattern. For example, meals that were abundant in Lactic Acid Bacteria were from all three dietary patterns. Some taxonomic groups were correlated with the nutritional content of the meals. Predictive metagenome analysis using PICRUSt indicated differences in some functional KEGG categories across the three dietary patterns and for meals clustered based on whether they were raw or cooked. Further studies are needed to determine the impact of ingested microbes on the intestinal microbiota, the extent of variation across foods, meals and diets, and the extent to which dietary microbes may impact human health. The answers to these questions will reveal whether dietary microbes, beyond probiotics taken as supplements—i.e., ingested with food—are important contributors to the composition, inter-individual variation, and function of our gut microbiota.
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Affiliation(s)
- Jenna M Lang
- Genome Center, University of California , Davis, CA , USA
| | - Jonathan A Eisen
- Genome Center, Evolution and Ecology, Medical Microbiology and Immunology, University of California , Davis, CA , USA
| | - Angela M Zivkovic
- Department of Nutrition, University of California , Davis, CA , USA ; Foods for Health Institute, University of California , Davis, CA , USA
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