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1. Efficient Molybdenum Hydrazonato Epoxidation Catalysts Operating under Green Chemistry Conditions: Water vs. Decane Competition

Author

Silvija Mrkonja, Mirna Mandarić, Dominique Agustin, Edi Topić, Jana Pisk, University of Zagreb, Laboratoire de chimie de coordination (LCC), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Croatian Government / European Union : European Regional Development Fund-Competitiveness and Cohesion Operational Programme (Grant KK.01.1.1.02.0016.), Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Green chemistry, chemistry.chemical_element, Epoxide, Epoxidation, Decane, TP1-1185, 010402 general chemistry, DFT calculations, 7. Clean energy, 01 natural sciences, Medicinal chemistry, Catalysis, Benzaldehyde, chemistry.chemical_compound, Cyclooctene, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Physical and Theoretical Chemistry, QD1-999, General Environmental Science, Dichloromethane, Molybdenum, 010405 organic chemistry, [CHIM.ORGA]Chemical Sciences/Organic chemistry, Chemical technology, TBHP in water, TBHP in decane, [CHIM.CATA]Chemical Sciences/Catalysis, 0104 chemical sciences, molybdenum, aroylhydrazone, epoxidation, catalysis, organic solvent-free process, Chemistry, chemistry, Organic solvent-free process, Aroylhydrazone
Abstract

Molybdenum compounds containing benzaldehyde-based hydrazones were obtained. The reaction in MeOH resulted with monomeric Mo complexes, [MoO2(L)(MeOH)], while the reaction in dichloromethane (DCM) provided oligomeric complexes, [MoO2(L)]n. The solid-state structures of the obtained compounds were investigated through Infrared Spectroscopy - Attenuated Total Reflection (IR-ATR), Thermogravimetric analysis (TGA), and via X-ray diffraction. The prepared molybdenum species were employed as cyclooctene epoxidation catalysts. TBHP (tert-butylhydroperoxide) in water and TBHP in decane were employed and compared as oxidants, with 0.25 mol% [Mo]. The catalyst activity and selectivity towards epoxide is &gt, 90% for all the reactions. The results have been linked to theoretical calculations, showing the importance of the first step, i.e., the transformation of [MoO2(L)(MeOH)] into the pentacoordinate [MoO2(L)].

Published
2021
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2. Tetranuclear molybdenum(vi) hydrazonato epoxidation (pre)catalysts: Is water always the best choice?

Author

Dominique Agustin, Višnja Vrdoljak, Jana Pisk, Department of Chemistry [Zagreb], Faculty of Science [Zagreb], University of Zagreb-University of Zagreb, Laboratoire de chimie de coordination (LCC), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Croatian Science Foundation, Croatia (IP-2016-06-4221)

Subjects
Tetranuclear molybdenum complexes, Aroylhydrazones, Epoxidation, TBHP inwater and decane, No organic solvent added, Cyclohexene, chemistry.chemical_element, Decane, 010402 general chemistry, 01 natural sciences, Catalysis, chemistry.chemical_compound, TBHP in water and decane, Cyclooctene, Polymer chemistry, Oxidizing agent, [CHIM.COOR]Chemical Sciences/Coordination chemistry, 010405 organic chemistry, Process Chemistry and Technology, Organic solvent, General Chemistry, 0104 chemical sciences, chemistry, Molybdenum, Density functional theory
Abstract

International audience; Self-assembled tetranuclear molybdenum(vi) complexes with hydrazonato ligands, [MoO2L]4, were tested as (pre)catalysts for cyclooctene and cyclohexene epoxidation without extra organic solvent added. Special attention was addressed to the comparison of oxidizing agents, TBHP in water vs. TBHP in decane. The idea was to test the greenness of the complete process. Density Functional Theory calculations were used to support and explain experimental catalytic result for tetranuclear self-assembled systems.

Published
2020
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3. Organic Salts and Merrifield Resin Supported [PM12O40]3− (M = Mo or W) as Catalysts for Adipic Acid Synthesis

Author

Dominique Agustin, Jana Pisk, Rinaldo Poli, Laboratoire de chimie de coordination (LCC), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), and European Union Seventh Framework Programme (FP7 2007–2013) - grant agreement n°291823 Marie Curie FP7-PEOPLE-2011-COFUND

Subjects
Cyclohexene, Pharmaceutical Science, chemistry.chemical_element, 010402 general chemistry, 01 natural sciences, Analytical Chemistry, Catalysis, Merrifield resin, lcsh:QD241-441, chemistry.chemical_compound, lcsh:Organic chemistry, Drug Discovery, Oxidizing agent, Organic chemistry, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Physical and Theoretical Chemistry, Hydrogen peroxide, Adipic acid, Aqueous solution, 010405 organic chemistry, Polyoxometalates, Organic Chemistry, polyoxometalates, cyclohexene, adipic acid, organic solvent-free process, 0104 chemical sciences, chemistry, Organic solvent-free process, Chemistry (miscellaneous), Molybdenum, Molecular Medicine
Abstract

Adipic acid (AA) was obtained by catalyzed oxidation of cyclohexene, epoxycyclohexane, or cyclohexanediol under organic solvent-free conditions using aqueous hydrogen peroxide (30%) as an oxidizing agent and molybdenum- or tungsten-based Keggin polyoxometalates (POMs) surrounded by organic cations or ionically supported on functionalized Merrifield resins. Operating under these environmentally friendly, greener conditions and with low catalyst loading (0.025% for the molecular salts and 0.001&ndash, 0.007% for the supported POMs), AA could be produced in interesting yields.

Published
2019
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4. Discrete mononuclear and dinuclear compounds containing a MoO 2 2+ core and 4-aminobenzhydrazone ligands: synthesis, structure and organic-solvent-free epoxidation activity

Author

Marina Cindrić, Gordana Pavlović, Višnja Vrdoljak, Dominique Agustin, Dubravka Šišak-Jung, Dubravka Matković-Čalogović, Jana Pisk, Danijela Cvijanović, School of Medicine, University of Zagreb, Division of General and Inorganic Chemistry [Zagreb], Department of Chemistry [Zagreb], Faculty of Science [Zagreb], University of Zagreb-University of Zagreb-Faculty of Science [Zagreb], University of Zagreb-University of Zagreb, Faculty of Textile Technology, Department of Applied Chemistry, University of Zagreb, Universität Zürich [Zürich] = University of Zurich (UZH), Laboratoire de chimie de coordination (LCC), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and In part : Croatian Science Foundation - project IP-2016-06-4221.

Subjects
Aqueous solution, 4-aminobenzoylhydrazone ligands, molybdenum(VI) complexes, epoxidation activity, Chemistry, Ligand, chemistry.chemical_element, 02 engineering and technology, General Chemistry, Organic solvent free, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Medicinal chemistry, Catalysis, 0104 chemical sciences, chemistry.chemical_compound, Salicylaldehyde, Cyclooctene, Molybdenum, Materials Chemistry, Density functional theory, [CHIM.COOR]Chemical Sciences/Coordination chemistry, 0210 nano-technology
Abstract

International audience; Cyclic dinuclear molybdenum(vi) complexes [MoO2(L1–3)]2 (1, 2-α, 2-β and 3) were synthesized through the use of coordination-driven self-assembly of a MoO22+ core and 4-aminobenzoylhydrazone ligands (salicylaldehyde (H2L1), 3-methoxysalicylaldehyde (H2L2) or 4-methoxysalicylaldehyde 4-aminobenzoylhydrazone (H2L3)). Their X-ray diffraction (XRD) analysis revealed that these types of ligands could serve as organic linkers for cis-octahedral complexes containing a MoO22+ core. Mononuclear complexes [MoO2(L1–3)(MeOH)] (1a–3a) and [MoO2(L1–3)(EtOH)] (1b, 2b-α, 2b-β and 3b) were also obtained. In the presence of strong donors, such as dmf, ligand substitution occurred and the structures of 1–3 changed into [MoO2(L1)(dmf)] (1c), [MoO2(L2)(dmf)] (2c) and [MoO2(L3)(H2O)]·dmf (3c·dmf), respectively. The dioxidomolybdenum(vi) complexes were tested for catalytic epoxidation of cyclooctene under eco-friendly reaction conditions by using aqueous tert-butyl hydroperoxide (TBHP) as an oxidant without the addition of an organic solvent. The present study showed much better activity of the dinuclear catalysts than the mononuclear ones due to the weak donor properties of the amino group and high geometric constraints occurring in such small sized self-assembled systems as confirmed by density functional theory calculations.

Published
2019
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5. Dioxotungsten(VI) complexes with isoniazid-related hydrazones as (pre)catalysts for olefin epoxidation: solvent and ligand substituent effects

Author

Biserka Prugovečki, Dubravka Matković-Čalogović, Predrag Novak, Dominique Agustin, Jana Pisk, Višnja Vrdoljak, Division of General and Inorganic Chemistry [Zagreb], Department of Chemistry [Zagreb], Faculty of Science [Zagreb], University of Zagreb-University of Zagreb-Faculty of Science [Zagreb], University of Zagreb-University of Zagreb, IUT 'A' - Département de Chimie [Castres], Institut Universitaire de Technologie - Paul Sabatier (IUT Paul Sabatier), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, Laboratoire de chimie de coordination (LCC), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Université Fédérale Toulouse Midi-Pyrénées

Subjects
tungsten, isoniazid, hydrazones, epoxidation, solvent-free, chemistry.chemical_classification, Olefin fiber, 010405 organic chemistry, Ligand, Stereochemistry, General Chemical Engineering, Substituent, Hydrazone, Aromaticity, General Chemistry, Nuclear magnetic resonance spectroscopy, 010402 general chemistry, 01 natural sciences, Medicinal chemistry, 0104 chemical sciences, Catalysis, chemistry.chemical_compound, chemistry, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Selectivity
Abstract

International audience; The mononuclear dioxotungsten(VI) complexes [WO2(L-3OMe)(D)] (1a and 1b), [WO2(L-4OMe)(D)] (2a and 2b) and [WO2(L-H)(D)] (3a and 3b) (D = EtOH (1a-3a) or MeOH (1b-3b); L-3OMe = 3-methoxy-2-oxybenzaldehyde isonicotinoyl hydrazonato, L-4OMe = 4-methoxy-2-oxybenzaldehyde isonicotinoyl hydrazonato, L-H = 2-oxybenzaldehyde isonicotinoyl hydrazonato) were synthesized by the reaction of [WO2(acac)(2)]center dot 0.5C(6)H(5)Me with the respective isoniazid-related hydrazone. The compounds were characterized by microanalysis, FT-IR and NMR spectroscopy, thermogravimetric analysis, and powder X-ray diffraction method. The crystal and molecular structures of 1a, 1b, 3a and [WO2(acac)(2)]center dot 0.5C(6)H(5)Me were determined by single crystal X-ray diffraction. The structures of 1a, 1b, 3a are mononuclear and form hydrogen bonded centrosymmetric dimers. In all three complexes, the dimers are also held together by pi center dot center dot center dot pi interactions between aromatic rings. The catalytic performances (activity and selectivity) of 1a-3a and 1b-3b towards alkene epoxidation by tert-butyl hydroperoxide (TBHP) were investigated under different conditions.

Published
2016
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6. Pyridoxal based ONS and ONO vanadium(V) complexes: Structural analysis and catalytic application in organic solvent free epoxidation

Author

Dominique Agustin, Jean-Claude Daran, Rinaldo Poli, Jana Pisk, Laboratoire de chimie de coordination (LCC), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Division of General and Inorganic Chemistry [Zagreb], Department of Chemistry [Zagreb], Faculty of Science [Zagreb], University of Zagreb-University of Zagreb-Faculty of Science [Zagreb], University of Zagreb-University of Zagreb, IUT 'A' - Département de Chimie [Castres], Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Universitaire de Technologie - Paul Sabatier (IUT Paul Sabatier), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Institut de Chimie de Toulouse (ICT), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut Universitaire de Technologie - Paul Sabatier (IUT Paul Sabatier), and Université de Toulouse (UT)-Université de Toulouse (UT)

Subjects
Stereochemistry, Vanadium(V) complexes, Vanadium, Epoxidation, Organic solvent-free, Mechanism, chemistry.chemical_element, Hydrazide, DFT calculations, Medicinal chemistry, Catalysis, chemistry.chemical_compound, Cyclooctene, Solvent free, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Physical and Theoretical Chemistry, Catalyst recovery, Epoxidation mechanism, Olefin fiber, Pyridoxal Schiff base, Schiff base, Ligand, [CHIM.ORGA]Chemical Sciences/Organic chemistry, Process Chemistry and Technology, Nuclear magnetic resonance spectroscopy, [CHIM.CATA]Chemical Sciences/Catalysis, Trigonal bipyramidal molecular geometry, chemistry
Abstract

International audience; A series of dinuclear and mononuclear oxovanadium(V) complexes containing tridentate Schiff base ligands derived from pyridoxal and appropriate thiosemicarbazide or hydrazide are reported. The compounds were characterised by elemental analysis, thermogravimetric analysis, IR and NMR spectroscopy. The molecular structure of the dioxido-vanadium(V) complex [VO2(HL5)]center dot MeOH center dot H2O (H2L5 = pyridoxal benzhydrazido ligand), determined by X-ray crystallography, reveals an unexpected distorted trigonal bipyramidal arrangement of the VO2 moiety. A DFT study of this molecule and of the related [VO2(H2L5)] complex of V-IV reveals a moderate effect of the oxidation state change on the bond distances and angles, pointing to solvation as the cause of the structural distortion. All complexes were tested as (pre) catalysts for olefin epoxidation by aqueous tert-butylhydroxyperoxide (TBHP) under solvent-free conditions. Low vanadium loadings (0.05% vs. olefin) resulted in good cyclooctene conversions and TOFs. The lifetime of one catalyst was explored through repeated runs with recovery/recycling. DFT calculations have also addressed the olefin epoxidation mechanism, which reveals the possible direct O atom transfer from the activated tert-butoxido (tBuOO(-)) ligand, without the need to generate a peroxido (022) ligand.

Published
2015
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7. Dioxomolybdenum(VI) and dioxotungsten(VI) complexes chelated with the ONO tridentate hydrazone ligand: synthesis, structure and catalytic epoxidation activity

Author

Dubravka Matković-Čalogović, Jelena Parlov Vuković, Jana Pisk, Dominique Agustin, Predrag Novak, Višnja Vrdoljak, Division of General and Inorganic Chemistry [Zagreb], Department of Chemistry [Zagreb], Faculty of Science [Zagreb], University of Zagreb-University of Zagreb-Faculty of Science [Zagreb], University of Zagreb-University of Zagreb, Laboratoire de chimie de coordination (LCC), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), IUT 'A' - Département de Chimie [Castres], Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Universitaire de Technologie - Paul Sabatier (IUT Paul Sabatier), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, and INA-Industrija nafte d.d.

Subjects
010405 organic chemistry, Stereochemistry, Ligand, Infrared spectroscopy, General Chemistry, Nuclear magnetic resonance spectroscopy, 010402 general chemistry, 01 natural sciences, Medicinal chemistry, Catalysis, 0104 chemical sciences, chemistry.chemical_compound, Salicylaldehyde, chemistry, Cyclooctene, Materials Chemistry, Chelation, [CHIM.COOR]Chemical Sciences/Coordination chemistry, molybdenum, tungsten, aroylhydrazone, epoxidation, solvent-free, Acetonitrile, Dichloromethane
Abstract

International audience; Synthesis of the dioxomolybdenum(vi) complexes [MoO2(L-3OMe)(EtOH)) (1), (MoO2(L-4OMe)(EtOH)] (2) and [MoO2(L-H)(EtOH)] (3) and dioxotungsten(VI) complexes [WO2(L-3OMe)(EtOH)] (4), [WO2(L-4OMe)(EtOH)] (5) and [WO2(L-H)](n) (6a) was carried out using [MO2(C5H7O2)(2)] = Mo or W) and the corresponding aroythydrazone ligand H2LR (3-methoxysalicylaldehyde 4-hydroxybenzhydrazone (H2L3OMe), 4-methoxysalicylaldehyde 4-hydroxybenzhydrazone (H2L4OMe), or salicylaldehyde 4-hydroxybenzhydrazone (H2LH) in ethanol. Compounds obtained upon heating of the mononuclear complexes in acetonitrile or dichtoromethane, [MO2(L-R)](n) (1a-6a) or [MoO2(L-3OMe)](2) (1b), respectively, were also investigated. Crystal and molecular structures of the mononuclear 1, 2 and 3, polynuclear 1a.MeCN and dinuclear 1b complexes were determined by the single crystal X-ray diffraction method. Powder X-ray diffraction showed isostructurality of 1 and 4, and 2 and 5. The complexes were further characterized by elemental analysis, IR spectroscopy, TO and DSC analyses, and one- and two-dimensional NMR spectroscopy. The catalytic performances of 1-5 and 6a were investigated for epoxidation of cyclooctene using aqueous tert-butyl hydroperoxide (TBHP) as the oxidant.

Published
2014
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