Maximilian N. Kopylovich

Ortho-Hydroxyphenylhydrazo-β-Diketones: Tautomery, Coordination Ability, and Catalytic Activity of Their Copper(II) Complexes toward Oxidation of Cyclohexane and Benzylic Alcohols

New hydrazone o-HO-phenylhydrazo-β-diketones (OHADB), R(1)NHN═CR(2)R(3) [R(1) = HO-2-C(6)H(4), R(2) = R(3) = COMe (H(2)L(1), 1), R(2)R(3) = COCH(2)C(Me)(2)CH(2)CO (H(2)L(2), 2), R(2) = COMe, R(3) = COOEt (H(2)L(4), 4); R(1) = HO-2-O(2)N-4-C(6)H(3), R(2)R(3) = COCH(2)C(Me)(2)CH(2)CO (H(2)L(3), 3), R(2) = COMe, R(3) = COOEt (H(2)L(5), 5), R(2)R(3) = COMe (H(2)L(6), 6A)], and their Cu(II) complexes [Cu(2)(CH(3)OH)(2)(μ-L(1))(2)] 7, [Cu(2)(H(2)O)(2)(μ-L(2))(2)] 8, [Cu(H(2)O)(L(3))] 9, [Cu(2)(μ-L(4))(2)](n) 10, [Cu(H(2)O)(L(5))] 11, [Cu(2)(H(2)O)(2)(μ-L(6))(2)] 12A and [Cu(H(2)O)(2)(L(6))] 12B were synthesized and fully characterized, namely, by X-ray analysis (4, 5, 7-12B). Reaction of 6A, Cu(NO(3))(2) and ethylenediamine (en) leads, via Schiff-base condensation, to [Cu{H(2)NCH(2)CH(2)N═C(Me)C(COMe)═NNC(6)H(3)-2-O-4-NO(2)}] (13), and reactions of 12A and 12B with en give the Schiff-base polymer [Cu{H(2)NCH(2)CH(2)N═C(Me)C(COMe)═NNC(6)H(3)-2-O-4-NO(2)}](n) 14. The dependence of the OHADB tautomeric equilibria on temperature, electronic properties of functional groups, and solvent polarity was studied. The OHADB from unsymmetrical β-diketones exist in solution as a mixture of enol-azo and hydrazo tautomeric forms, while in the solid state all the free and coordinated OHADB crystallize in the hydrazo form. The relative stabilities of various tautomers were studied by density functional theory (DFT). 7-14 show catalytic activities for peroxidative oxidation (in MeCN/H(2)O) of cyclohexane to cyclohexanol and cyclohexanone, for selective aerobic oxidation of benzyl alcohols to benzaldehydes in aq. solution, mediated by TEMPO radical, under mild conditions and for the MW-assisted solvent-free synthesis of ketones from secondary alcohols with tert-butylhydroperoxide as oxidant.

Copper(II) coordination polymers derived from triethanolamine and pyromellitic acid for bioinspired mild peroxidative oxidation of cyclohexane.

The new inorganic 1D coordination polymer [Cu2(H3tea)2(mu4-pma)]n has been prepared, via self-assembly in aqueous medium, from copper(II) nitrate, triethanolamine (H3tea), pyromellitic acid (H4pma) and lithium hydroxide, and characterized by IR spectroscopy, elemental and single-crystal X-ray diffraction analyses. This compound and the related 2D polymer [Cu2(mu-H2tea)(2){mu3-Na2(H2O)4}(mu6-pma)]n.10nH2O are shown to mimic the alkane partial oxidation activity of the multicopper particulate methane monooxygenase, acting as catalysts precursors for the peroxidative oxidation of cyclohexane into cyclohexanol and cyclohexanone, by hydrogen peroxide (as green oxidant) and at room temperature in acidic MeCN/H2O medium. An overall yield (based on cyclohexane) of 29% has been achieved.

Zinc(II) ortho-hydroxyphenylhydrazo-β-diketonate complexes and their catalytic ability towards diastereoselective nitroaldol (Henry) reaction

The zinc(II) complexes with ortho-hydroxy substituted arylhydrazo-β-diketonates [Zn(2)(CH(3)OH)(2)(μ-L(1))(2)] (5), [Zn{(CH(3))(2)SO}(H(2)O)(L(2))] (6), [Zn(2)(H(2)O)(2)(μ-L(3))(2)] (7) and [Zn(H(2)O)(2)(L(4))]·H(2)O (8) were synthesized by reaction of a zinc(II) salt with the appropriate hydrazo-β-diketone, HO-2-C(6)H(4)-NHN=C{C(=O)CH(3)}(2) (H(2)L(1), 1), HO-2-O(2)N-4-C(6)H(3)-NHN=C{C(=O)CH(3)}(2) (H(2)L(2), 2), HO-2-C(6)H(4)-NHN=CC(=O)CH(2)C(CH(3))(2)CH(2)C(=O) (H(2)L(3), 3) or HO-2-O(2)N-4-C(6)H(3)-NHN=[CC(=O)CH(2)C(CH(3))(2)CH(2)C(=O) (H(2)L(4), 4). They were fully characterized, namely by X-ray diffraction analysis that disclosed the formation of extensive H-bonds leading to 1D chains (5 and 6), 2D layers (7) or 3D networks (8). The thermodynamic parameters of the Zn(II) reaction with H(2)L(2) in solution, as well as of the thermal decomposition of 1-8 were determined. Complexes 5-8 act as diastereoselective catalysts for the nitroaldol (Henry) reaction. The threo/erythro diastereoselectivity of the β-nitroalkanol products ranges from 8:1 to 1:10 with typical yields of 80-99%, depending on the catalyst and substrate used.

Self-Assembled 3D Heterometallic CuII/FeII Coordination Polymers with Octahedral Net Skeletons: Structural Features, Molecular Magnetism, Thermal and Oxidation Catalytic Properties

The new three-dimensional (3D) heterometallic Cu(II)/Fe(II) coordination polymers [Cu(6)(H(2)tea)(6)Fe(CN)(6)](n)(NO(3))(2n)·6nH(2)O (1) and [Cu(6)(Hmdea)(6)Fe(CN)(6)](n)(NO(3))(2n)·7nH(2)O (2) have been easily generated by aqueous-medium self-assembly reactions of copper(II) nitrate with triethanolamine or N-methyldiethanolamine (H(3)tea or H(2)mdea, respectively), in the presence of potassium ferricyanide and sodium hydroxide. They have been isolated as air-stable crystalline solids and fully characterized including by single-crystal X-ray diffraction analyses. The latter reveal the formation of 3D metal-organic frameworks that are constructed from the [Cu(2)(μ-H(2)tea)(2)](2+) or [Cu(2)(μ-Hmdea)(2)](2+) nodes and the octahedral [Fe(CN)(6)](4-) linkers, featuring regular (1) or distorted (2) octahedral net skeletons. Upon dehydration, both compounds show reversible escape and binding processes toward water or methanol molecules. Magnetic susceptibility measurements of 1 and 2 reveal strong antiferromagnetic [J = -199(1) cm(-1)] or strong ferromagnetic [J = +153(1) cm(-1)] couplings between the copper(II) ions through the μ-O-alkoxo atoms in 1 or 2, respectively. The differences in magnetic behavior are explained in terms of the dependence of the magnetic coupling constant on the Cu-O-Cu bridging angle. Compounds 1 and 2 also act as efficient catalyst precursors for the mild oxidation of cyclohexane by aqueous hydrogen peroxide to cyclohexanol and cyclohexanone (homogeneous catalytic system), leading to maximum total yields (based on cyclohexane) and turnover numbers (TONs) up to about 22% and 470, respectively.

Template Syntheses of Copper(II) Complexes from Arylhydrazones of Malononitrile and their Catalytic Activity towards Alcohol Oxidations and the Nitroaldol Reaction: Hydrogen Bond-Assisted Ligand Liberation and E/Z Isomerisation

A one-pot template condensation of 2-(2-(dicyanomethylene)hydrazinyl)benzenesulfonic acid (H(2)L(1), 1) or 2-(2-(dicyanomethylene)hydrazinyl)benzoic acid (H(2)L(2), 2) with methanol (a), ethylenediamine (b), ethanol (c) or water (d) on copper(II), led to a variety of metal complexes, that is, mononuclear [Cu(H(2)O)(2)(κO(1),κN(2)L(1a)] (3) and [Cu(H(2)O)(κO(1),κN(3)L(1b))] (4), tetranuclear [Cu(4)(1κO(1),κN(2):2κO(1)L(2a))(3)-(1κO(1), κN(2):2κO(2)L(2a))] (5), [Cu(2)(H(2)O)(1κO(1), κN(2):2κO(1)L(2c))-(1κO(1),1κN(2):2κO(1),2 κN(1)- L(2c))](2) (6) and [Cu(2)(H(2)O)(2)(κO(1),κN(2)- L(1dd))-(1κO(1),κN(2):2κO(1)L(1dd))(μ-H(2)O)](2·) 2H(2)O (7·2H(2)O), as well as polymer- ic [Cu(H(2)O)(κO(1),1κN(2):2κN(1)L(1c))](n) (8) and [Cu(NH(2)C(2)H(5))(κO(1),1κN(2):2κN(1)L(2a))](n) (9). The ligands 2-SO(3)H-C(6)H(4)-(NH)N=C{(CN)[C(NH(2))-(=NCH(2)CH(2)NH(2))]} (H(2)L(1b), 10), 2-CO(2)H-C(6)H(4)-(NH)N={C(CN)[C(OCH(3))-(=NH)]} (H(2)L(2a), 11) and 2-SO(3)H-C(6)H(4)-(NH)N=C{C(=O)-(NH(2))}(2) (H(2)L(1dd), 12) were easily liberated upon respective treatment of 4, 5 and 7 with HCl, whereas the formation of cyclic zwitterionic amidine 2-(SO(3)(−))-C(6)H(4)-N=NC(-C=(NH(+))CH(2)CH(2)NH)(=CNHCH(2)CH(2)NH) (13) was observed when 1 was treated with ethylenediamine. The hydrogen bond-induced E/Z isomerization of the (HL(1d))(−) ligand occurs upon conversion of [{Na(H(2)O)(2)(μ-H(2)O)(2)}(HL(1d))](n) (14) to [Cu(H(2)O)(6)][HL(1d)](2)·2H(2)O (15) and [{CuNa(H(2)O)-(κN(1),1κO(2):2κO(1)L(1d))(2)}K(0.5)(μ-O)(2)]n·H(2)O (16). The synthesized complexes 3–9 are catalyst precursors for both the selective oxidation of primary and secondary alcohols (to the corresponding carbonyl compounds) and the following diastereoselective nitroaldol (Henry) reaction, with typical yields of 80–99%.

Poly(vinyl) chloride membrane copper-selective electrode based on 1-phenyl-2-(2-hydroxyphenylhydrazo)butane-1,3-dione

1-Phenyl-2-(2-hydroxyphenylhydrazo)butane-1,3-dione (H(2)L) was used as an effective ionophore for copper-selective poly(vinyl) chloride (PVC) membrane electrodes. Optimization of the composition of the membrane and of the conditions of the analysis was performed, and under the optimized conditions the electrode has a detection limit of 6.30×10(-7) M Cu(II) at pH 4.0 with response time 10s and displays a linear EMF versus log[Cu(2+)] response over the concentration range 2.0×10(-6) to 5.0×10(-3) M Cu(II) with a Nernstian slope of 28.80±0.11 mV/decade over the pH range of 3.0-8.0. The sensor is stable for 9 weeks and exhibits good selectivity with respect to alkali, alkali earth and transition metal ions (e.g. Na(+), K(+), Ba(2+), Ca(2+), Zn(2+), Cd(2+), Co(2+), Mn(2+), Ni(2+), Fe(2+), Al(3+)) in the 3.0-8.0 pH range. It was successfully applied for the direct determination of copper(II) in zinc, aluminum and nickel based alloys, in soils polluted by oil, and as an indicator electrode for potentiometric titration of copper ions with EDTA.

Alkoxy‐1,3,5‐triazapentadien(e/ato) Copper(II) Complexes: Template Formation and Applications for the Preparation of Pyrimidines and as Catalysts for Oxidation of Alcohols to Carbonyl Products

Template combination of copper acetate (Cu(AcO)(2)⋅H(2)O) with sodium dicyanamide (NaN(C≡N)(2), 2 equiv) or cyanoguanidine (N≡CNHC(=NH)NH(2), 2 equiv) and an alcohol ROH (used also as solvent) leads to the neutral copper(II)-(2,4-alkoxy-1,3,5-triazapentadienato) complexes [Cu{NH=C(OR)NC(OR)=NH}(2)] (R = Me (1), Et (2), nPr (3), iPr (4), CH(2)CH(2)OCH(3) (5)) or cationic copper(II)-(2-alkoxy-4-amino-1,3,5-triazapentadiene) complexes [Cu{NH=C(OR)NHC(NH(2))=NH}(2)](AcO)(2) (R = Me (6), Et (7), nPr (8), nBu (9), CH(2)CH(2)OCH(3) (10)), respectively. Several intermediates of this reaction were isolated and a pathway was proposed. The deprotonation of 6-10 with NaOH allows their transformation to the corresponding neutral triazapentadienates [Cu{NH=C(OR)NC(NH(2))=NH}(2)] 11-15. Reaction of 11, 12 or 15 with acetyl acetone (MeC(=O)CH(2)C(=O)Me) leads to liberation of the corresponding pyrimidines NC(Me)CHC(Me)NCNHC(=NH)OR, whereas the same treatment of the cationic complexes 6, 7 or 10 allows the corresponding metal-free triazapentadiene salts {NH(2)C(OR)=NC(NH(2))=NH(2)}(OAc) to be isolated. The alkoxy-1,3,5-triazapentadiene/ato copper(II) complexes have been applied as efficient catalysts for the TEMPO radical-mediated mild aerobic oxidation of alcohols to the corresponding aldehydes (molar yields of aldehydes of up to 100 % with >99 % selectivity) and for the solvent-free microwave-assisted synthesis of ketones from secondary alcohols with tert-butylhydroperoxide as oxidant (yields of up to 97 %, turnover numbers of up to 485 and turnover frequencies of up to 1170 h(-1)).

Copper(II) complexes with a new carboxylic-functionalized arylhydrazone of β-diketone as effective catalysts for acid-free oxidations

The aquasoluble [Cu(H2O)((CH3)2NCHO)(HL)] (2) and [Cu2(CH3OH)2(μ-HL)2] (3) CuII complexes were prepared by reaction of CuII nitrate hydrate with the new 3-(2-hydroxy-4-carboxyphenylhydrazone)pentane-2,4-dione (H3L, 1), in the presence (for 2) or absence (for 3) of (n-C4H9)2SnO, and characterized by elemental analysis, IR spectroscopy and X-ray single crystal diffraction. Magnetic susceptibility measurements, in compound 3, reveal strong antiferromagnetic coupling between the CuII ions through the μ2-phenoxido-O atoms, J = −203(1) cm−1. Complexes 2 and 3 act as catalyst precursors for the acid-free peroxidative oxidation of cyclohexane to the mixture of cyclohexyl hydroperoxide (primary product), cyclohexanol and cyclohexanone (TONs and yields up to 163 and 14.4%, respectively), as well as for the selective aerobic oxidation of benzyl alcohols to benzaldehydes in aqueous solution, mediated by a TEMPO radical, under mild conditions (TONs and yields up to 390 and 94%, respectively). In the alkane oxidations, 2 and 3 appear to behave as “dual role catalysts” combining, in one molecule, an active metal centre and an acidic promoting group, to provide a high activity of the system even without any acid promoter.

Single-pot template transformations of cyanopyridines on a PdII centre: syntheses of ketoimine and 2,4-dipyridyl-1,3,5-triazapentadiene palladium(II) complexes and their catalytic activity for microwave-assisted Suzuki–Miyaura and Heck reactions

[2 + 3] cycloaddition of the pyrrolin N-oxide (-)O[upper bond 1 start](+)N[double bond, length as m-dash]CHCH(2)CH(2)C[upper bond 1 end]Me(2) with 2-cyanopyridine NC(5)H(4)(2-CN) in the presence of PdCl(2) at room temperature in acetone gives the ketoimine palladium(II) complex cis-[PdCl(2){N(=[upper bond 1 start]CCH(2)CH(2)C(Me)(2)N[upper bond 1 end]H)C(=O)C(5)H(4)N}] containing the (E)-N-(5,5-dimethylpyrrolidin-2-ylidene)picolinamide ligand, in good yield (85%). The reaction of with 3-cyanopyridine NC(5)H(4)(3-CN) or 4-cyanopyridine NC(5)H(4)(4-CN) under the same experimental conditions gives the simple adducts of cyanopyridines trans-[PdCl(2){NC(5)H(4)(3-CN)}(2)] or trans-[PdCl(2){NC(5)H(4)(4-CN)}(2)] , respectively. When the cyanopyridines NC(5)H(3)R(1)R(2) (R(1) = 2-CN, R(2) = H ; R(1) = 3-CN, R(2) = H ; R(1) = 4-CN, R(2) = H ; R(1) = 4-CN, R(2) = 2-Cl ; R(1) = 3-CN, R(2) = 5-Me ) are heated at 100 degrees C for 12 h with 2-butanone oxime (used as a reagent and solvent) in the presence of PdCl(2), the 2,4-dipyridyl-1,3,5-triazapentadienate (or bis-imidoylamidinate) palladium(II) complexes [Pd{HN[double bond, length as m-dash]C(NC(5)H(3)R(2))NC(NC(5)H(3)R(2))[double bond, length as m-dash]NH}(2)] (2-NC(5)H(3), R(2) = H ; 3-NC(5)H(3), R(2) = H ; 4-NC(5)H(3), R(2) = H ; 4-NC(5)H(3), R(2) = 2-Cl ; 3-NC(5)H(3), R(2) = 5-Me ) are synthesized by one-pot template transformations followed by deprotonation by a base (n-PrNH(2)). The compounds were characterized by IR, (1)H and (13)C NMR spectroscopies, FAB(+)-MS, elemental analyses and, in the cases of , , and , also by X-ray diffraction analyses. The catalytic activity of complexes and was studied under microwave irradiation for C-C coupling reactions, in the solid phase on a silica gel support, and it was found that complex is the most active one with the maximum TON of 2.0.10(5) and TOF of 1.3.10(4) min(-1) for Suzuki-Miyaura, and TON of 800 and TOF of 27 min(-1) for Heck reactions.

Heteronuclear iron(III)-chromium(III) hydroxo complexes and hydroxides, and their catalytic activity towards peroxidative oxidation of alkanes

The equilibrium compositions of the products of hydrolysis of Fe(III) and Cr(III) in their single or binary nitrate solutions, as a function of pH and neutralisation degree have been established and Fe(III)–Cr(III) hydroxides and products of their thermolysis have been obtained and characterized by potentiometric titration, thermal analysis, IR spectroscopy and X-ray powder diffraction, and an Fe(III)–Cr(III) interaction recognised in the binary systems. The obtained aquahydroxo complexes and metal hydroxides have been applied as catalysts for the homogeneous or heterogeneous, respectively, peroxidative oxidation of cyclohexane and cyclopentane to the corresponding ketones and alcohols, at room temperature. The effects of various parameters, such as pH, degree of neutralisation and reagents molar ratios, have been investigated and correlations between the catalytic activity and the form of the hydroxo complex were recognised for the homogeneous systems, whereas for the heterogeneous mixed (heteronuclear) hydroxides a synergic effect has been detected for the oxidation of cyclohexane, the catalytic activity (which can reach 30% yields and 30 turnover numbers (TONs)) being above those of the individual hydroxides.