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Appavoo D, van Wyk JL, Spencer LC, Guzei IA, Darkwa J. Pyrazolyl-based zinc(II) carboxylate complexes: synthesis, characterization and catalytic behaviour in ring opening polymerization of ε-caprolactone and D,L-lactide. Results in Chemistry 2022. [DOI: 10.1016/j.rechem.2021.100261] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Tumeli TR, van Wyk JL. Synthesis and characterization of ionic functionalized cobalt and chromium complexes derived from salicylaldimine ligands: Application as catalysts in the coupling of carbon dioxide with propylene oxide. Inorganica Chim Acta 2021. [DOI: 10.1016/j.ica.2021.120563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Appavoo D, Spencer LC, Guzei IA, Gómez-García CJ, van Wyk JL, Darkwa J. Ring opening polymerization of d,l-lactide and ε-caprolactone catalysed by (pyrazol-1-yl)copper(ii) carboxylate complexes. RSC Adv 2021; 11:13475-13485. [PMID: 35423870 PMCID: PMC8697578 DOI: 10.1039/d1ra00339a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 03/24/2021] [Indexed: 01/24/2023] Open
Abstract
1,2-Bis{(3,5-dimethylpyrazol-1-yl)methyl}benzene (L) reacts with [Cu(OAc)2] and C6H5COOH, 4-OH-C6H4COOH, 2-Cl-C6H4COOH and (3,5-NO2)2-C6H3COOH to afford the copper complexes [Cu2(C6H5COO)4(L)2] (1), [Cu2(4-OH-C6H4COO)4(L)2] (2), [Cu2(2-Cl-C6H4COO)4(L)2]n (3) and [Cu{(3,5-NO2)2-C6H3COO}2L]n (4) which are characterised by IR, mass spectrometry, elemental analyses, and X-ray crystallography. The structural data revealed two geometries that are adopted by the complexes: (i) paddle wheel in 1, 2·7H2O, 3 and (ii) regular chains in 3 and 4. Magnetic studies show strong antiferromagnetic couplings in the paddle wheel complexes and a weak antiferromagnetic coupling in the monometallic chain one. Catalysis studies performed with these complexes (1–4) showed that they initiate ring opening polymerization (ROP) of ε-caprolactone (ε-CL) under solvent-free conditions and d,l-lactide in toluene at elevated temperatures. Polycaprolactone (PCL) and poly(d,l-lactide) (PLA) obtained from the polymerization reactions are of low molecular weights (858 for PCL and 602 Da for PLA for initiator 1) and polydispersity indices (typically 2.16 for PCL and 1.64 for PLA with 1 as the initiator). End group analysis of the polymers, determined by MALDI-ToF MS, indicates that the polymers have benzoate, hydroxyl, methoxy and cyclic end groups. We report the synthesis, structure and complete characterization of four new pyrazolyl carboxylate-based copper(ii) complexes that catalyze the ring opening polymerization of ε-caprolactone under solvent-free conditions and of d,l-lactide in toluene.![]()
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Affiliation(s)
- Divambal Appavoo
- Department of Chemical Sciences, University of Johannesburg P.O. Box X524, Auckland Park, 2006 South Africa
| | - Lara C Spencer
- Department of Chemistry, University of Wisconsin-Madison Madison WI 53706 USA
| | - Ilia A Guzei
- Department of Chemical Sciences, University of Johannesburg P.O. Box X524, Auckland Park, 2006 South Africa .,Department of Chemistry, University of Wisconsin-Madison Madison WI 53706 USA
| | - Carlos J Gómez-García
- Department of Inorganic Chemistry and ICMol, C/ Catedrático José Beltrán, 2. University of Valencia 46980 Paterna Valencia Spain
| | - Juanita L van Wyk
- Department of Chemical Sciences, University of Johannesburg P.O. Box X524, Auckland Park, 2006 South Africa
| | - James Darkwa
- Department of Chemical Sciences, University of Johannesburg P.O. Box X524, Auckland Park, 2006 South Africa
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Ramollo GK, Strydom I, Fernandes MA, Lemmerer A, Ojwach SO, van Wyk JL, Bezuidenhout DI. Fischer Carbene Complexes of Iridium(I) for Application in Catalytic Transfer Hydrogenation. Inorg Chem 2020; 59:4810-4815. [PMID: 32212623 PMCID: PMC7311058 DOI: 10.1021/acs.inorgchem.0c00079] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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New examples of the very rare class
of iridium(I) Fischer carbene complexes (FCCs) are reported from the
facile transmetalation from group 6 FCCs. Postcomplexation modification
of either the carbene ligand or the ancillary coligands results in
a tunable IrI metal center, for unprecedented application
as a (pre)catalyst in a benchmark transfer hydrogenation reaction.
The introduction of an aminocarbene ligand with a pendant N-donor
moiety capable of hemilabile coordination yielded the best catalytic
results with turnover frequencies reaching 445 h–1 and requiring 0.1 mol % catalyst and 0.5 mol % base loading, respectively. A benchmark transfer hydrogenation is
catalyzed by an iridium(I) acyclic aminocarbene of the Fischer type
with a pendant N donor.
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Affiliation(s)
- G Kabelo Ramollo
- Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg 2050, South Africa
| | - Ian Strydom
- Chemistry Department, University of Pretoria, Private Bag X20, Hatfield 0028, Pretoria, South Africa
| | - Manuel A Fernandes
- Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg 2050, South Africa
| | - Andreas Lemmerer
- Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg 2050, South Africa
| | - Stephen O Ojwach
- School of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg, South Africa
| | - Juanita L van Wyk
- Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg 2050, South Africa
| | - Daniela I Bezuidenhout
- Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg 2050, South Africa.,Laboratory of Inorganic Chemistry, Environmental and Chemical Engineering, University of Oulu, P.O. Box 3000, 90014 Oulu, Finland
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Kangara EF, Peega T, Harmse L, van Wyk JL, Levendis DC, Kotzé IA. Conformational analysis and potential anticancer activity of [Pt(phen)(L1-κS)2] studied by single crystal X-ray diffraction and variable temperature 1H and 195Pt NMR spectroscopy. NEW J CHEM 2019. [DOI: 10.1039/c8nj06010j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Conformers of [Pt(phen)(L1-κS)2] observed in solution as a result of π-stacking interactions between the unusual κS-coordinated N,N-diethyl-N′-1-naphthoylthioureato ligands and 1,10-phenanthroline.
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Affiliation(s)
- Edmore F. Kangara
- Molecular Sciences Institute
- School of Chemistry
- University of the Witwatersrand
- Johannesburg 2050
- South Africa
| | - Tebogo Peega
- Molecular Sciences Institute
- School of Chemistry
- University of the Witwatersrand
- Johannesburg 2050
- South Africa
| | - Leonie Harmse
- Division of Pharmacology
- Department of Pharmacy and Pharmacology
- Faculty of Health Sciences
- University of the Witwatersrand
- 7 York Road
| | - Juanita L. van Wyk
- Molecular Sciences Institute
- School of Chemistry
- University of the Witwatersrand
- Johannesburg 2050
- South Africa
| | - Demetrius C. Levendis
- Molecular Sciences Institute
- School of Chemistry
- University of the Witwatersrand
- Johannesburg 2050
- South Africa
| | - Izak A. Kotzé
- Molecular Sciences Institute
- School of Chemistry
- University of the Witwatersrand
- Johannesburg 2050
- South Africa
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van Wyk JL, Mapolie S, Lennartson A, Håkansson M, Jagner S. The Synthesis of Copper(II) Salicylaldiminato Complexes and their Catalytic Activity in the Hydroxylation of Phenol. ACTA ACUST UNITED AC 2014. [DOI: 10.1515/znb-2007-0305] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The synthesis of copper(II) salicylaldiminato complexes and their application in the catalytic hydroxylation of phenol is reported. Tetracoordinated copper complexes (Cu(Ln)2) were obtained by reacting the N-phenylsalicylaldimine ligands (HL1 -HL7) with copper acetate in a 2 : 1 mole ratio. The reaction of N-(2,6-diisopropyl)phenyl-3,5-di-tert-butylsalicylaldimine (HL7) with copper acetate in a 1 : 1 mole ratio afforded a dinuclear complex, which was not obtained with the other ligand systems. All complexes were characterized using FT-IR and elemental analysis. X-Ray crystal structures of complexes 2, 5 and 8 have also been obtained. The catalytic activity of these complexes was evaluated in the hydroxylation of phenol using oxygen and hydrogen peroxide as co-oxidants in aqueous media in the pH range 3 - 6. All complexes studied were found to be active for the hydroxylation process over the pH range studied with higher selectivity for catechol formation.
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Affiliation(s)
- Juanita L. van Wyk
- Chemistry Department, University of the Western Cape, Private Bag X17, Bellville, 7535, South Africa
| | - Selwyn Mapolie
- Chemistry Department, University of the Western Cape, Private Bag X17, Bellville, 7535, South Africa
| | - Anders Lennartson
- Department of Chemistry, Göteborg University, SE-412 96 Göteborg, Sweden
| | - Mikael Håkansson
- Department of Chemistry, Göteborg University, SE-412 96 Göteborg, Sweden
| | - Susan Jagner
- Department of Chemical and Biological Engineering, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
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Appavoo D, Omondi B, Guzei IA, van Wyk JL, Zinyemba O, Darkwa J. Bis(3,5-dimethylpyrazole) copper(II) and zinc(II) complexes as efficient initiators for the ring opening polymerization of ε-caprolactone and d,l-lactide. Polyhedron 2014. [DOI: 10.1016/j.poly.2013.11.011] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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van Wyk JL, Omondi B, Appavoo D, Guzei IA, Darkwa J. Solvent-Free Synthesis of 3,5-Di-Tert-Butylpyrazole and 3,5-Di-Substituted-Butylpyrazol-1-Ylethanol. Journal of Chemical Research 2012. [DOI: 10.3184/174751912x13397801313284] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A high-yield, solvent-free approach to the synthesis of 1,3,5-trisubstituted pyrazoles is reported. Four compounds, (3,5-di-tert-butyl-1H-pyrazole, (2-(3,5-dimethyl-1H-pyrazol-1-yl)ethanol, 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethanol, 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethanol were readily prepared by solvent-free condensation of the appropriate dike-tone and the respective hydrazine. The crystal structures of the three pyrazolyl-ethanols are typical of N-substituted pyrazoles. All three pyrazolyl compounds show interesting inter-molecular hydrogen bonding. For the 3,5-dimethyl compound the molecules form discrete hydrogen bonded dimers within a unit cell, while for the others the hydrogen bonding is in a head-to-tail arrangement resulting in the formation of chains.
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Affiliation(s)
- Juanita L. van Wyk
- Department of Chemistry, University of Johannesburg, PO Box 524, Auckland Park, 2006, South Africa
| | - Bernard Omondi
- Department of Chemistry, University of Johannesburg, PO Box 524, Auckland Park, 2006, South Africa
| | - Divambal Appavoo
- Department of Chemistry, University of Johannesburg, PO Box 524, Auckland Park, 2006, South Africa
| | - Ilia A. Guzei
- Department of Chemistry, University of Johannesburg, PO Box 524, Auckland Park, 2006, South Africa
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - James Darkwa
- Department of Chemistry, University of Johannesburg, PO Box 524, Auckland Park, 2006, South Africa
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Mugo JN, Mapolie SF, van Wyk JL. Cu(II) and Ni(II) complexes based on monofunctional and dendrimeric pyrrole-imine ligands: Applications in catalytic liquid phase hydroxylation of phenol. Inorganica Chim Acta 2010. [DOI: 10.1016/j.ica.2010.05.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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van Wyk JL, Mapolie SF, Lennartson A, Håkansson M, Jagner S. The catalytic oxidation of phenol in aqueous media using cobalt(II) complexes derived from N-(aryl) salicylaldimines. Inorganica Chim Acta 2008. [DOI: 10.1016/j.ica.2007.10.031] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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