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Reis Conceição N, Nesterova OV, Rajnák C, Boča R, Pombeiro AJL, Guedes da Silva MFC, Nesterov DS. New members of the polynuclear manganese family: MnMn single-molecule magnets and MnMn antiferromagnetic complexes. Synthesis and magnetostructural correlations. Dalton Trans 2020; 49:13970-13985. [PMID: 32985628 DOI: 10.1039/d0dt02652b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthesis, crystal structures and magnetic properties are reported for three novel mixed-valence tetranuclear [MnII2MnIII2(HBuDea)2(BuDea)2(EBA)4] (1), [MnII2MnIII2(HBuDea)2(BuDea)2(DMBA)4] (2) and undecanuclear [MnII3MnIII8O4(OH)2(BuDea)6(DMBA)8] (3) clusters, where H2BuDea is N-butyldiethanolamine, HEBA is 2-ethylbutyric acid and HDMBA is 2,2-dimethylbutyric acid. The compounds have been prepared through self-assembly reactions of manganese(ii) chloride with H2BuDea and respective carboxylic acid in methanol solution in air, affording 1 with HEBA, and 2 or 3 with HDMBA, depending on the experimental conditions. The single crystal X-ray analysis reveals that 1 and 2 have similar centrosymmetric structures based on the {M4(μ3-O)2(μ-O)4} core, while 3 discloses the unprecedented {M11(μ-O)4(μ3-O)12} one. The Mn4 complexes display single-molecule magnet (SMM) behavior with a S = 9 spin ground state and a high energy barrier Ueff/kB of up to 51 K. The magnetic properties of 2 are successfully modeled with JMnIII-MnIII/hc = 25.7 cm-1 and two JMnIII-MnII/hc constants of 3.1 and -0.93 cm-1 (data correspond to the Ĥ = -Jŝ1·ŝ2 formalism). The Mn11 cluster exhibits a paramagnetic behavior with dominant antiferromagnetic coupling. A possible influence of intermolecular effects and of different peripheries of the magnetic cores designed by using 2-ethylbutyrate (in 1) or 2,2-dimethylbutyrate (in 2) on the magnetic properties of 1 and 2 is discussed. The experimental magnetostructural correlations for the {MnII2MnIII2(μ3-O)2(μ-O)4} cores, supported by broken symmetry DFT calculations, disclose the X-MnIIIMnIII angle and MnIII-O distance (where MnIII-X and MnIII-O are axial Jahn-Teller bonds) as the structural factors having the strongest influence on JMnIII-MnIII exchange coupling. It is shown that two JMnIII-MnII constants are necessary for the correct description of magnetic exchange couplings in the {MnII2MnIII2(μ3-O)2(μ-O)4} tetranuclear unit.
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Affiliation(s)
- Nuno Reis Conceição
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
| | - Oksana V Nesterova
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
| | - Cyril Rajnák
- Department of Chemistry, Faculty of Natural Sciences, University of SS Cyril and Methodius, 917 01 Trnava, Slovakia
| | - Roman Boča
- Department of Chemistry, Faculty of Natural Sciences, University of SS Cyril and Methodius, 917 01 Trnava, Slovakia
| | - Armando J L Pombeiro
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
| | - M Fátima C Guedes da Silva
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
| | - Dmytro S Nesterov
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal. and Peoples' Friendship University of Russia (RUDN University), 6 Miklukho-Maklaya st., Moscow 117198, Russia
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Nesterova OV, Bondarenko OE, Pombeiro AJL, Nesterov DS. Phenoxazinone synthase-like catalytic activity of novel mono- and tetranuclear copper(ii) complexes with 2-benzylaminoethanol. Dalton Trans 2020; 49:4710-4724. [PMID: 32207490 DOI: 10.1039/d0dt00222d] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Three novel coordination compounds, [Cu(ca)2(Hbae)2] (1), [Cu(va)2(Hbae)2] (2) and [Cu4(va)4(bae)4]·H2O (3), have been prepared by self-assembly reactions of copper(ii) chloride (1 and 2) or tetrafluoroborate (3) and CH3OH (1 and 3) or CH3CN (2) solution of 2-benzylaminoethanol (Hbae) and cinnamic (Hca, 1) or valeric (Hva, 2 and 3) acid. Crystallographic analysis revealed that both 1 and 2 have mononuclear crystal structures, wherein the complex molecules are H-bonded forming extended supramolecular chains. The tetranuclear structure of 3 is based on the {Cu4(μ3-O)4} core, wherein the metal atoms are bound together by μ3 oxygen bridges from 2-benzylaminoethanol forming an overall cubane-like configuration. The strong hydrogen bonding in 1-3 leads to the joining of the neighbouring molecules into 1D chains. Concentration-dependent ESI-MS studies disclosed the equilibria between di-, tri- and tetranuclear species in solutions of 1-3. All three compounds act as catalysts for the aerobic oxidation of o-aminophenol to the phenoxazinone chromophore (phenoxazinone synthase-like activity), with the maximum reaction rates of 4.0 × 10-7, 2.5 × 10-7 and 2.1 × 10-7 M s-1 for 1, 2 and 3, respectively, supported by the quantitative yield of the product after 24 h. The dependence of the reaction rates on catalyst concentrations is evidence of reaction orders higher than one relative to the catalyst. Kinetic and ESI-MS data allowed us to assume that the tetranuclear species, originating from 1, 2 and 3 in solution, possess considerably higher activity than the species of lower nuclearity. Mechanistic and isotopic 18O-labelling experiments suggested that o-aminophenol coordinates to CuII species with the formation of reactive intermediates, while the oxygen from 18O2 is not incorporated into the phenoxazinone chromophore.
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Affiliation(s)
- Oksana V Nesterova
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
| | - Olena E Bondarenko
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
| | - Armando J L Pombeiro
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
| | - Dmytro S Nesterov
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal. and Peoples' Friendship University of Russia (RUDN University), 6 Miklukho-Maklaya st., Moscow 117198, Russia
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Nesterova OV, Nesterov DS, Jezierska J, Pombeiro AJL, Ozarowski A. Copper(II) Complexes with Bulky N-Substituted Diethanolamines: High-Field Electron Paramagnetic Resonance, Magnetic, and Catalytic Studies in Oxidative Cyclohexane Amidation. Inorg Chem 2018; 57:12384-12397. [PMID: 30209935 DOI: 10.1021/acs.inorgchem.8b02145] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The novel coordination compounds [Cu2(H tBuDea)2(OAc)2] (1) and [Cu2(H nBuDea)2Cl2]· nH2O (2) have been prepared through the reaction of the respective copper(II) salts with N- tert-butyldiethanolamine (H2 tBuDea, for 1) or N-butyldiethanolamine (H2 nBuDea, for 2) in methanol solution. Crystallographic analysis reveals that, in spite of the common binuclear {Cu2(μ-O)2} core, the supramolecular structures of the complexes are drastically different. In 1 binuclear molecules are linked together by H-bonds into 1D chains, while in 2 the neighboring pairs of binuclear molecules are H-bonded, forming tetranuclear aggregates. Variable-temperature (1.8-300 K) magnetic susceptibility measurements of 1 and 2 show a dominant antiferromagnetic behavior. Both complexes are also studied by HF-EPR spectroscopy. While the interaction between Cu(II) centers in 1 can be described by a single coupling constant J = 130.1(3) cm-1 (using H = JS1 S2), the crystallographically different {Cu2(μ-O)2} pairs in 2 are expected exchange from ferro- to antiferromagnetic behavior (with J ranging from -32 to 110 cm-1, according to DFT calculations). Complexes 1 and 2 act as catalysts in the amidation of cyclohexane with benzamide, employing tBuOO tBu as oxidant. The maximum achieved conversion of benzamide (20%, after 24 h reaction time) was observed in the 1/ tBuOO tBu system. In the cases of tBuOO(O)CPh or tBuOOH oxidants, no significant amidation product was observed, while for tBuOO(O)CPh, the oxidative dehydrogenation of cyclohexane occurred, giving cyclohexene, to afford the allylic ester (cyclohex-2-en-1-yl benzoate) as the main reaction product.
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Affiliation(s)
- Oksana V Nesterova
- Centro de Química Estrutural, Instituto Superior Técnico , Universidade de Lisboa , Av. Rovisco Pais , 1049-001 Lisboa , Portugal
| | - Dmytro S Nesterov
- Centro de Química Estrutural, Instituto Superior Técnico , Universidade de Lisboa , Av. Rovisco Pais , 1049-001 Lisboa , Portugal
| | - Julia Jezierska
- Faculty of Chemistry , University of Wroclaw , 14 Joliot-Curie Str. , 50-383 , Wroclaw , Poland
| | - Armando J L Pombeiro
- Centro de Química Estrutural, Instituto Superior Técnico , Universidade de Lisboa , Av. Rovisco Pais , 1049-001 Lisboa , Portugal
| | - Andrew Ozarowski
- National High Magnetic Field Laboratory , Florida State University , 1800 East Paul Dirac Drive , Tallahassee , Florida 32310 , United States
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Nesterova OV, Nesterov DS, Vranovičová B, Boča R, Pombeiro AJL. Heterometallic Cu IIFe III and Cu IIMn III alkoxo-bridged complexes revealing a rare hexanuclear M 6(μ-X) 7(μ 3-X) 2 molecular core. Dalton Trans 2018; 47:10941-10952. [PMID: 30019733 DOI: 10.1039/c8dt02290a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The novel hexanuclear complexes [Cu4Fe2(OH)(Piv)4(tBuDea)4Cl]·0.5CH3CN (1) and [Cu4Mn2(OH)(Piv)4(tBuDea)4Cl] (2) were prepared through one-pot self-assembly reactions of copper powder and iron(ii) or manganese(ii) chloride with N-tert-butyldiethanolamine (H2tBuDea) and pivalic acid (HPiv) in acetonitrile. Crystallographic studies revealed the uncommon molecular core type M6(μ-X)7(μ3-X)2 in 1 and 2, which can be viewed as a combination of two trimetallic M3(μ-X)2(μ3-X) fragments joined by three bridging atoms. The analysis and classification of the hexanuclear complexes having a M3(μ-X)2(μ3-X) moiety as a core forming fragment using data from the Cambridge Structural Database (CSD) were performed. Variable-temperature (1.8-300 K) magnetic susceptibility measurements of 1 showed a decrease of the effective magnetic moment value at low temperature, indicative of antiferromagnetic coupling between the magnetic centres (JFe-Cu/hc = -6.9 cm-1, JCu-Cu/hc = -4.1 cm-1, JFe-Fe/hc = -24.2 cm-1). Complex 1 acts as a catalyst in the reaction of mild oxidation of cyclohexane with H2O2, showing the yields of products, cyclohexanol and cyclohexanone, up to 17% using pyrazinecarboxylic acid as a promoter. In the oxidation of cis-1,2-dimethylcyclohexane with m-chloroperoxybenzoic acid (m-CPBA), 70% of retention of stereoconfiguration was observed for tertiary alcohols. Compound 1 also catalyses the amidation of cyclohexane with benzamide. In all three catalytic reactions the by-products were investigated in detail and discussed.
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Affiliation(s)
- Oksana V Nesterova
- Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001 Lisboa, Portugal.
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Heterometallic CoII-CoIII-MII alkoxido-bridged heptanuclear motifs (M = Cu, Zn). Syntheses, crystal structures and magnetic properties. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2017.05.077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Nesterov DS, Nesterova OV, Pombeiro AJ. Homo- and heterometallic polynuclear transition metal catalysts for alkane C H bonds oxidative functionalization: Recent advances. Coord Chem Rev 2018. [DOI: 10.1016/j.ccr.2017.08.009] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Seppälä P, Sillanpää R, Lehtonen A. Structural diversity of copper(II) amino alcoholate complexes. Coord Chem Rev 2017. [DOI: 10.1016/j.ccr.2017.06.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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