1,3,2-Oxazaphosphole catalyse the oxygenation of triphenylphosphine to its oxide by molecular oxygen.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

C39.33H42Cl4Cu2N6O8.67, trigonal, R3 (no. 148), a = 27.819(4) angstrom, c = 14.447(6) angstrom, V = 9682.8 angstrom(3), Z = 9, R-gt(F) = 0.040, wR(ref)(F-2) = 0.109, T = 293 K.

C39.33H42Cl4Cu2N6O8.67, trigonal, R3̅ (no. 148), a = 27.819(4) Å, c = 14.447(6) Å, V = 9682.8 Å3, Z = 9, Rgt(F) = 0.040, wRref(F2) = 0.109, T = 293 K.

Abstract C39.33H42Cl4Cu2N6O8.67, trigonal, R3̅ (no. 148), a = 27.819(4) Å, c = 14.447(6) Å, V = 9682.8 Å3, Z = 9, Rgt(F) = 0.040, wRref(F2) = 0.109, T = 293 K.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Some 4′-substituted flavonols undergo [4 + 2] cycloaddition with 3,5-di-tert-butyl-1,2-benzoquinone to give trioxanaphthacenes.

Reaction of one molar equivalent of 3,3′-iminobis(N,N-dimethylpropylamine (idpa)), N-benzoylanthranilic acid (N-baaH) and [Cu(CH3CN)4](ClO4) in acetonitrile resulted in the formation of a stable ionic copper(II) complex without additional solvent coordination. The composition and molecular structure of [Cu(idpa)(N-baa)]ClO4 was fully determined by IR, UV–vis, and X-ray crystal analysis. The complex has a distorted square planar CuN3O core. The oxygenation of 3-hydroxy-2-phenylquinolin-4(1H)-one (QuinH2) using [Cu(idpa)(N-baa)]ClO4 as a catalyst results in the oxidative cleavage of the heterocyclic ring to give a N-benzoylanthranilic acid and CO as a mimic of quercetinase and 3-hydroxy-1,4-dihydroquinolin-4-one 2,4-dioxygenase action.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The preparation and characterization of tetranuclear Cu4(bnac)4(μ-OEt)4 complex is described. Crystallographic characterization of this complex has shown that the co-ordination geometry around copper(II) ions is distorted square pyramidal (monoclinic, C2/c, a=13.3980(2)Å, b=14.6080(2)Å, c=25.7460(4)Å, α=90.00°, β=103.4090(10)°, γ=90.00°, V=4901.59(13)Å3, Z=8). The in situ-generated Cu2(bnac)2(μ-OEt)4(4R-py)4 complexes were suitable catalysts for the catalytic oxidation of 3,5-DTBCH2 to 3,5-DTBQ with dioxygen at ambient condition in good yields. The catalytic activity was found to obey Michaelis–Menten type kinetics and increase with electron-releasing substituent on co-ordinated pyridines.

Several copper compounds (CuCl, CuCl2, CuSO4, Cu(NO3)2, Cu(OAc)2, Cu(OCH3)2, and Cu(OCH3)(Cl)) have been used as catalysts for the oxidation of 2-aminophenol with dioxygen at 60°C in DMF to 2-aminophenoxazine-3-one; a comparison of their activities was made through kinetic measurements. Stronger coordinating donor N-ligands (bpy, phen) accelerate the reaction rate remarkably and the amount of ligand influences the molecularity of the CuCl-catalyzed reaction. The overall second order rate equation was found at CuCl to phen ratio of 1:0 (k2/60°C=11.3±0.5×102mol−3l3s−1), while the reaction is zero order with respect to 2-aminophenol concentration at a CuCl to phen ratio of 1:2 (k0/60°C=13.9±0.7×10−2mol−3l3s−1). The kinetics of the CuCl(phen)-catalyzed reaction measured at 60°C resulted in a rate equation with first order dependence on copper, dioxygen and 2-aminophenol. The rate constant, activation enthalpy, and entropy at 333.16K are as follows: kobs=2.42±0.22mol−2dm6s−1, Ea=25±1kJmol−1, ΔH‡=22±1kJmol−1 and ΔS‡=−170±13Jmol−1K−1. The catalytic systems investigated can be viewed as functional models of the enzyme phenoxazinone synthase.

C25H18CuN5O4, triclinic, P1̅ (no. 2), a = 7.300(1) Å, b = 11.985(1) Å, c = 13.190(1) Å, α = 88.15(1)°, β = 78.68(1)°, γ = 78.62(1)°, V = 1109.3 Å3, Z = 2, Rgt(F) = 0.048, wRref(F2) = 0.134, T = 293 K.

The oxygenolytic cleavage of flavonolate coordinated to copper(II) with the auxiliary ligand 3,3′-iminobis(N,N-dimethylpropylamine), [CuII(fla)(idpa)]ClO4, is enhanced by the addition of acetate and benzoate. Monodentate coordination of the flavonolate forced by the carboxylate ligands is believed to be the reason for the higher reaction rates.

The complex [Fe(Hdmg)2(py)2], referred to as ferroxime(II), was found to be a selective catalyst for the oxidative denitrification of nitroalkanes such as 1-nitroethane, 1-nitropropane, 2-nitropropane, 1-nitropentane and nitrocyclohexane to the corresponding aldehydes or ketones. The oxidation was performed in DMF and EtOH under Ar in the presence of various oxidants such as O2, TBHP, H2O2 at room temperature, and was followed by glc. The substrate specificity of the catalyst either in DMF or EtOH solution shows that there are no significant differences in the conversions with the exception of 1-nitropentane and nitrocyclohexane. The effect of various oxidants shows that the catalytic oxidations were effective only with TBHP and H2O2. No oxidation products could be detected when O2 was used. The best conversions (TN) have been obtained with TBHP in EtOH (up to 24%, TN=9.3), followed by H2O2 (1.7%, TN=0.5).

The preparation and characterization of dinuclear [MII(dbcat)(idpa)]2 (M=Zn (1), Cu (3); dbcat=3,5-di-tert-butylcatecholate; idpa=3,3′-iminobis(N,N-dimethylpropylamine)) complexes are described. Crystallographic characterization of the complex [CuII(dbcat)(idpa)]2 has shown that the co-ordination geometry around copper(II) ions is distorted square pyramidal (triclinic, P-1, a=10.576(1) Å, b=11.927(1) Å, c=12.621(1) Å, α=77.89(1)°, β=88.65(1)°, γ=70.21(1)°, V=1462.7(2) Å3, Z=2, R=0.0387). Both 1 and 3 were suitable catalysts for the catalytic oxidation of dbcatH2 to dtbq (dtbq=3,5-di-tert-butyl-1,2-benzoquinone) with dioxygen at ambient conditions in good yields. However, on the basis of kinetic studies the copper- and zinc-catalyzed reactions showed different mechanisms. In the first case valence tautomerism [CuII(dbcat)(idpa)]⇄[CuI(dbsq)(idpa)] precedes the reaction with O2, while with the zinc complex metal-bound catecholate reacts directly with O2 with the formation of free superoxide anion.

Primary and secondary nitro compounds react with dioxygen in the presence of copper metal and N ligands such as N,N,N',N'-tetramethylethylenediamine (tmeda), 2,2'-bipyridine (bpy), and 1,10-phenantroline (phen) in various solvents to form aldehydes or ketones. More coordinating solvents as well as donor N ligands accelerate the reaction remarkably. The oxygenolysis of 2-nitropropane (NPH) in the presence of copper and tmeda in DMF results in acetone and acetone oxime. The amount of tmeda influences the chemoselectivity, higher tmeda concentrations preferentially lead to the formation of the oxime. The kinetics of the reaction, measured at 90 degreesC, resulted in a rate equation of first-order dependence on copper and dioxygen and second-order dependence on 2-nitropropane, The rate constant, activation enthalpy, and entropy at 363.16 K are as follows: k(cat) = (5.37 +/- 0.34) x 10(-2) mol(-3) dm(9)s(-1), E-a = 131 +/- 4 kJ mol(-1), DeltaHdouble dagger = 127 +/- 4 kJ mol(-1) and AS' = 80 13 J mol(-1) K-1. The catalytically active intermediates Cull (NP) 2 (tmeda) and Cu-II(NO2)(2)(t-meda) in the catalytic cycle were isolated and their structures determined by X-ray crystallography. The kinetics of the stoichiometric oxygenation of Cu-II(NP)(2) (tmeda) to Cu-II(NO2)(2)(tmeda) and acetone resulted in the overall second-order rate equation with a rate constant, activation enthalpy, and entropy at 313.16 K of k(s) 0.46 +/- 0.02 mol(-1) dm(3) s(-1), E-a = 38 +/- 1 kJ mol(-1), DeltaHdouble dagger = 35 +/- 1 kJ mol(-1) and DeltaSdouble dagger = -142 +/- 13 J mol(-1) K-1, respectively.

[Cu(phen)(2)(fla)]ClO4 was prepared by treating [Cu(CH3CN)(4)]-ClO4 with flavonol (flaH) in the presence of 1,10-phenanthroline (phen) as a co-ligand. Its oxygenation in DMF (or CH3CN) solution at elevated temperature gave the (O-benzoylsalicylato)copper(II) complex [Cu(phen)(2)(O-bs)]ClO4 (bs = benzoylsalicylato) and carbon monoxide via an endoperoxide intermediate. Crystallographic characterisation of [Cu(phen)(2)(O-bs)]ClO4 as the CH2Cl2 solvate [triclinic, space group P (1) over bar, a = 10.499(3) Angstrom, b = 12.556(4) Angstrom, c = 17.094(5) Angstrom, alpha = 72.69(2), beta = 89.35(2), gamma = 69.19(2)degrees, V = 1999.7(10) Angstrom(3), Z = 2, R1 = 0.0962] shows that the molecule has a distorted trigonal-bipyramidal structure (tau = 0.96). The oxygenolysis was monitored by spectrophotometry, and the pseudo-first-order rate constant k'(phen) was found to be (2.47 +/- 0.11) x 10(-4) s(-1) at 120degreesC. Complexes of [Cu(L)(4'R-fla)(2)] (L = phen, bpy, TMEDA; R = H, OCH3, CH3, Cl) were also prepared by treating the complexes Cu(4'R-fla)(2) with nitrogen-containing co-ligands. Their oxygenation resulted in the corresponding complexes Cu(L)(2HOpg)(2) (2HOpg = 2-hydroxyphenylglyoxylate) derived by spontaneous hydrolysis of Cu(L)(bpg)(2) (bpg = 2-benzoatophenylglyoxylate). The (phenylglyoxylato)-copper complexes were probably formed via 1,2-dioxetan intermediates, since the oxygenation of Cu(phen)(fla)(2) showed chemiluminescence with bands at 506, 546, and 578 nm in the emission spectrum due to the decomposition of a 1,2-dioxetan species. Labelling experiments with an O-18(2)/O-16(2) mixture (1:3) showed the incorporation of both O-18 atoms of O-18(2) into the flavonolate ligand. The kinetics of the oxygenolysis of Cu(L)(fla)(2) gave rate constants according to the rate law -d[Cu(L)(4'R-fla)(2)]/dt = k[Cu(L)(4'R-fla)(2)][O-2]: k/m(-1) s(-1) = (9.50 +/- 0.60) x 10(-2) (L = phen), (2.40 +/- 0.10) x 10(-2) (L = bpy), (2.00 +/- 0.10) x 10(-2) (L = TMEDA) m(-1) s(-1) at 353.16 K. The oxygenolysis of the complexes Cu(phen)(4'R-fla)(2) fits a Hammett linear free energy relationship and an increase of the electron density on the copper ion makes the oxygenation reaction faster. ((C) Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002).