Binuclear copper(II) complexes with acyldihydrazones of saturated carboxylic acids and pyruvic acid

Copper(II) binuclear complexes with acyldihydrazones of saturated carboxylic acids and pyruvic acid in which the coordination polyhedra are connected by polymethylene chains of different length (1 to 5 units) were synthesized and studied by chemical and thermogravimetric analysis, IR spectroscopy, and EPR. The structure of binuclear copper(II) complex with succinic acid acyldihydrazone [Cu₂L · 4Py] · 2Py was determined by X-ray diffraction. The crystals are monoclinic: a = 14.3795(6), b = 8.8736(4), c = 15.9147(7) Å, β = 101.062(3)°, space group P2₁/c, Z = 2. The number of independent reflections with I > 2σ(I) = 2804, R = 0.042, R _w = 0.087. The copper atoms are spaced by a chain of seven σ bonds at 8.922 Å. The coordination polyhedron can be described as a tetragonal pyramid highly distorted toward a trigonal bipyramid. The EPR spectra of solutions of complexes based on malonic, succinic, glutaric, and adipinic acids exhibit a poorly resolved signal of seven HFS lines with a constant of (26.3–27.0) × 10^?4 cm^?1, which attests to the presence of weak exchange interactions between paramagnetic centers. An increase in the length of the polymethylene spaur suppresses exchange interactions, and the EPR spectrum of the complex based on pimelic acid acyldihydrazone shows a signal of four HFS lines with a constant of 43.8 × 10^?4 cm^?1 typical of monomeric copper(II) complexes.     

Binuclear copper(II) complexes with acyldihydrazones of <Emphasis Type="Italic">N</Emphasis>-benzenesulfonyl-<Emphasis Type="Italic">L</Emphasis>-aspartic acid

The structure and the EPR spectra of copper(II) coordination compounds with acyldihydrazones of N-benzenesulfonyl-L-aspartic acid and salicylaldehyde (2-hydroxyacetophenone) were described. The compounds were studied by chemical and thermal analyses, IR spectroscopy, and EPR. The molecular and crystal structures of copper(II) complexes with N-benzenesulfonyl-L-aspartic acid bis(salicylidene)hydrazone (H₄L¹) [Cu₂L¹ · 2Py] · 1.5 H₂O was determined by X-ray diffraction. The crystals are triclinic: a = 10.4714(4) Å, b = 12.9702(5) Å, c = 14.6187(9) Å, α = 104.763(2)°, β = 93.082(2)°, γ = 111.4240(10)°, space group P \(\bar 1\), Z = 2. The binuclear complexes containing copper cations whose coordination polyhedra are connected by an aliphatic spacer (Cu...Cu, 8.669 Å) are additionally linked by phenoxy bridges (Cu...Cu, 3.398 Å). The EPR spectra of these compounds in solutions exhibit an isotropic signal of seven HFS lines due to two equivalent copper ions with the spin Hamiltonian parameters g = 2.115?2.120, a _Cu = (35.5?38.0) × 10^?4 cm^?1, which is indicative of weak exchange interactions between the paramagnetic sites.     

Spacer-armed binuclear copper(ii) complexes with salicylidene hydrazones of N-benzoylaminodicarboxylic acids

The structure and EPR spectra of copper(II) complexes with bis(salicylidene)hydrozones of N-benzoyl-L-aspartic and N-benzoyl-L-glutamic acids have been described. The compounds have been studied by chemical and thermal analyses, IR spectroscopy, and EPR spectroscopy. The molecular and crystal structure of the copper(II) complex with bis(salicylidene)hydrozone of N-benzoyl-L-aspartic acid (H₄L) of composition [Cu₂L · 2Py] · 2CH₃OH · H₂O has been determined by X-ray single-crystal diffraction. The crystals are monoclinic: a = 10.3316(7) Å, b = 16.7552(9) Å,c = 11.0137(6) Å, β = 105.758(3)°, space group P2₁, Z = 2. The complex has a polymeric structure composed of alternating copper-containing binuclear fragments bound to each other either via phenoxy bridges or via an aliphatic spacer (the Cu…Cu distances are 3.471 Å and 8.939 Å, respectively). The EPR spectra of the solutions of the complexes under study shows an isotropic signal comprising seven HFS lines due to two equivalent copper nuclei with the spin Hamiltonian parameters g = 2.115–2.122 and a _Cu = (36.1–36.9) × 10^?4 cm^?1, which indicates the reaization of weak exchange coupling of the paramagnetic centers.     

Structure and EPR spectra of binuclear copper(II) complexes with acyldihydrazones of benzenedicarboxylic acids and trifluoroacetylacetone

Binuclear copper(II) complexes with acyldihydrazones of benzenedicarboxylic acid and trifluoroacetylacetone have been synthesized and studied. The structure of the copper(II) complex with diacylhydrazone of 1,3-benzenedicarboxylic acid (H₄L) of composition [Cu₂L · 2LPy] has been studied by X-ray diffraction. The crystals are triclinic: a = 9.2298(4) Å, b = 11.8510(6) Å, c = 13.8314(7) Å, α = 90.780(3)°, β = 96.124(3)°, γ = 99.264(3)°, space group \(P\bar 1\), Z = 2. The number of symmetry-unrelated reflections with I > 2σ(I) 5941; R = 0.0357, R _w = 0.0589. The complex contains two equivalent copper atoms at a distance of 9.56 Å from each other in the square-planar coordination environment. The high-temperature EPR spectra of the complexes show a signal of seven HFS lines indicating the coupling of unpaired electrons to two equivalent copper nuclei (g = 2.113?2.116, a _Cu = 37.0?37.2 × 10^?4 cm^?1).     

Binuclear copper(II) complexes with acyldihydrazones of benzenedicarboxylic acids with pyrrolidine or piperidine

The adducts of binuclear copper(II) complexes with acyldihydrazones formed by 1,3- or 1,4-benzenedicarboxylic acid and some nitrogen-containing Lewis bases (pyrrolidine, piperidine) were synthesized and studied. The structure of copper(II) complex with bis(salicylidene)hydrazone of terephthalic acid (H₄L), [Cu₂L(Pirr)₄] · CH₃OH, was determined by X-ray diffraction data. The crystals are monoclinic: a = 15.5142(7) Å, b = 13.8784(6) Å, c = 17.8873(8) Å; β = 91.990(2)°, space group C2/c, Z = 4. The number of symmetrically independent reflections was 4269, R = 0.0303, R _w = 0.0827. The complex contains two equivalent copper atoms located at a 11.021 Å is a tetragonal pyramid. EPR spectral features of the adducts were studied.     

Structure and EPR spectra of binuclear copper(II) complexes with acyldihydrazones of benzenedicarboxylic acids and 5-substituted 2-hydroxyacetophenones

Binuclear copper(II) complexes with acyldihydrazones of 1,3- or 1,4 benzenedicarboxylic acid and 5-methyl- or 5-bromo-2-hydroxyacetophenone in which coordination polyhedra are connected by an aromatic bridge have been synthesized and studied. The structure of the copper(II) complex with diacylhydrazone of isophthalic acid and 2-hydroxy-5-methylacetophenone (H₄L) of composition [Cu₂L · 3Py] was studied by X-ray diffraction. The crystals are monoclinic: a = 12.1996(12) Å, b = 17.7295(17) Å, c = 17.9339(17) Å, β = 109.7450(10)°, space group P2₁/n, Z = 4. The complex is of the “dimer of dimers” type and contains two binuclear subunits that bind together into a centrosymmetric dimer owing to the coordination of the copper cation to the phenoxyl oxygen atom of a neighboring binuclear molecule to form the Cu₂O₂ moiety, in which the copper atoms are 3.409 Å apart. The distance between the copper(II) cations in the binuclear subunit is 8.56 atoms (2N + O) of the doubly deprotonated acylhydrazone moiety and the nitrogen atom of the pyridine molecule. One of the copper cation is additionally coordinated to an extra pyridine molecule so that its coordination sphere is completed to a tetragonal pyramid. The second copper atom is involved in additional interaction with the phenoxyl oxygen atom of the neighboring molecule. The EPR spectra of solutions of the binuclear complexes show an isotropic signal of four HFS lines (g _o = 2.065–2.143, a _Cu = 52.1–66.5 × 10^?4 cm^?1) typical of mononuclear copper(II) complexes.     

Binuclear copper(II) complexes with acyldihydrazones of 1,4-cyclohexanedicarboxylic acid

The binuclear copper(II) complexes with acyldihydrazones formed by 1,4-cyclohexanedicarboxylic acid and salicylaldehyde or 2-hydroxyacetophenone were synthesized and studied. The structure of the complex with 1,4-cyclohexanedicarboxylic acid bis(salicylidene)hydrazone (H₄L¹) [Cu₂L¹(Py)₂] was studied by X-ray diffraction. The crystals are triclinic: a = 8.1852(4) Å, b = 8.5157(5) Å, c = 11.6553(7) Å, α = 80.678(3)°, β = 70.041(4)°, γ = 74.803(3)°. Space group \(P\bar 1\), Z = 1. The number of symmetrically independent reflections with I > 2(σ(I)) is 2245, R = 0.0395; R _w = 0.0917. The complex contains two equivalent copper atoms located at a 10.772 Å distance from each other. The coordination polyhedra have a square geometry and are involved in the intermolecular π/π-stacking. The EPR spectra of solutions of the binuclear complexes show an isotropic signal of seven HFS lines (g = 2.113–2.118, A _Cu ≈ 38 G), indicating interaction between the unpaired electrons and the two equivalent copper nuclei. The possible exchange interaction channels were analyzed.     

The structure and EPR spectra of binuclear copper(II) complexes with acyldihydrazones of β-diketones

The synthesis and structure of binuclear copper(II) complexes with acyldihydrazones of some β-diketones are described. The molecular structure of the copper(II) complex [Cu₂L·4Py] with trifluoroacetylacetone succinyldihydrazone (H₄L) was determined by the single-crystal X-ray analysis. Central atoms are bridged by a chain of seven σ-bonds with a Cu...Cu distance of 8.750 Å. EPR spectra of copper(II) complexes with acyldihydrazones of trifluoroacetylacetone and lower dicarboxylic acids containing from one to four methylene groups in the aliphatic spacer show the seven-line HFS due to spin-spin coupling of unpaired electrons with the two equivalent copper nuclei (g = 2.110, a = (38.5–40.5)⊙10^?4 cm^?1). By extending polymethylene spacer, as well as by modifying starting β-diketone, an exchange interaction between paramagnetic centers is suppressed.     

Crystal structure of the complex of copper(II) with 3-(2-hydroxy-3-sulfo-5-nitrophenylazo)-pentadione-2,4

A new complex of copper (II) with 3-(2-hydroxy-3-sulfo-5-nitrophenylazo)-pentadione-2,4 (HL) is synthesized and analyzed by single crystal XRD. The crystals are monoclinic: a = 7.7563(4) Å, b = 24.0157(12) Å, c = 24.6353(13) Å, β = 91.9490(10)°, V = 4586.2(4) ų, space group P2₁/c, Z = 2, ρ_calc = 1.713 g/cm³, R = 0.0695. The environment of the copper atom is formed by three oxygen atoms, the nitrogen atom of tetradentate ligand, and the oxygen atom of a water molecule.     

Crystal structure of adducts of copper(II) acetylacetonate and hexafluoroacetylacetonate with 4-aminopyridine

Single crystal X-ray diffraction is used to investigate two synthesized β-diketonate complexes of copper(II) with aminopyridine: Cu(4-NH₂Py)(aa)₂ (I) and Cu(4-NH₂Py)(hfa)₂ (II). The crystals of I and II have a monoclinic system; the unit cell parameters of I are: P2₁/n space group, a = 8.2921(3) Å, b = 14.7243(5) Å, c = 13.4970(4) Å, β = 102.426(1)°, V = 1609.32(9) ų, Z = 4; for II: C2/c space group, a = 23.5704(5) Å, b = 11.4977(2) Å, c = 16.0285(3) Å, β = 109.265(1)°, V = 4100.6(1) ų, Z = 8. The structures of I and II are molecular; they are composed of isolated molecules. The coordination polyhedron of the copper atom is formed by the O atoms of two acetylacetonate ligands (Cu-O 1.940(2)–2.171(2) I and the O atoms of two hexafluoroacetylacetonate ligands (Cu-O 1.940(2)–2.215(3) Å) in II. The molecules of 4-NH₂Py are bonded to the copper atom via the nitrogen atom of the aromatic ring (Cu-N 2.008(2) Å in I and Cu-N 1.978(3) Å in II). Noncoordinated amino groups join the molecules of the complexes together by means of N-H…O hydrogen bonds.     

Structure of the hexanuclear Cu(II) β-diketonate complex

The structure of the hexanuclear copper(II) β-diketonate complex with gfa (hexafluoroacetylacetone) and dpm (dipivalylmethanate) ligands was studied by low-temperature (T = 100 K) X-ray diffraction. Crystal data for Cu₆(gfa)₄(dpm)₄(OH)₄ [C₆₄H₈₄Cu₆F₂₄O₂₀]: a = 28.2364(7) Å, b = 12.8072(3) Å, c = 24.7199(7) Å, β= 115.900(1)°, V = 8041.5(4) ų, space group C2/m, Z = 4, d _calc 1.661 g/cm³. The coordination polyhedra of the copper atoms — squares and octahedra — are formed by the oxygen atoms of the gfa and dpm ligands and groups. In all cases, the Cu-O distances vary from 1.89 Å to 2.13 Å. The complexes follow the sites of the rhombohedral sublattice with the parameters a _c ≈ 14.4 Å and a _c ≈ 61.5°.     

Crystal and molecular structure of (hexafluoroacetylacetonato) (pivaloylacetonato)copper(II)

The crystal structure of (hexafluoroacetylacetonato)(pivaloylacetonato)copper(II) has been determined. Crystal data for CuO₄C₁₃H₁₄F₆: a = 8.288(2) Å, b = 8.682(2) Å, c = 12.307(2) Å; α = 90.75(3)°, β = 94.29(3)°, γ = 106.60(3)°; V = 845.7(3) ų, space group \(P\overline 1 \), Z = 2, d_calc = 1.617 g/cm³. The coordination polyhedron of the copper atom is formed by four oxygen atoms of two different β-diketonate ligands with Cu-O distances within 1.874–1.946 Å; the O-Cu-O bond angles are 94.8° and 90.6°. The complexes are united into centrosymmetrical “dimers” with Cu...Cu distances of 4.365 Å.     

EPR study of the nature of the impurity centers responsible for the scintillation properties of the Li<Subscript>2</Subscript>Zn<Subscript>2</Subscript>(MoO<Subscript>4</Subscript>)<Subscript>3</Subscript> crystal

The binary molybdate Li₂Zn₂(MoO₄)₃ of a new crystal type was characterized by EPR, optical spectroscopy, and X-ray diffraction methods. The crystals have the Pnma symmetry group and the lattice parameters a = 5.1139(5) Å, b = 10.4926(13) Å, c = 17.6445(22) Å; Z = 4. The crystals possess scintillation properties; emission is caused by the presence of impurity levels in the forbidden band. The EPR studies of the nature of the impurity centers responsible for the scintillation characteristics of the crystal showed that the centers were Cu²⁺ ions substituted for zinc ions in the oxygen octahedra. The directions of the main values of the g and tensors (g _zz , A _zz ) correspond to the direction of O-Cu-O of the oxygen octahedron distorted along the Z axis. The EPR spectra of the copper ions are described by the spin Hamiltonian with the parameters g _‖ = 2.38, g _⊥ = 2.06; A _‖ = 116 G, A _⊥ = 0 G.     

Structure of A Coordination Polymer [Cu(En)<Subscript>2</Subscript>CrO<Subscript>4</Subscript>]<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>

The crystal structure of [Cu(En)₂CrO₄]_n (En is ethylenediamine) is determined: a = 14.7359(4) Å, b = 9.8083(3) Å, c = 14.2664(4) Å, V = 2061.98(10) ų, space group Cmce, Z = 8, d_x = 1.931 g/cm³. It is demonstrated that the studied phase is isostructural with [Сu(Еn)₂SO₄]_n. A pseudotetragonal copper atom coordination (Cu–N 2.0204 Å and 2.0244 Å, ∠N–Cu–N 84.73°) is completed to distorted octahedral by two oxygen atoms of chromate anions (Cu–O 2.433 Å and 2.380 Å).     

Copper(II) complex with salicylaldehyde <Emphasis Type="Italic">N</Emphasis>-(2-salicylideneiminoglutaryl)hydrazone: Synthesis and structure

A copper(II) complex with salicylaldehyde N-(2-salicylideneiminoglutaryl)hydrazone (H₄L) of the formula [Cu₂L · 2Py]₂ · 8H₂O (I) was obtained and characterized by X-ray diffraction. The crystals are monoclinic, space group P2₁, a = 13.0663 Å, b = 16.5553 Å, c = 17.7650 Å, β = 97.9420°; Z = 4. The complex is tetranuclear with a “dimer-of-dimers” structure in which the copper cations of two binuclear subunits are linked by phenoxy bridges. The EPR spectra of solutions of complex I show a superposition of two signals of four HFS lines (g ₁ = 2.111, a ₁ = 56.8 × 10^?4 cm^?1 and g ₂ = 2.183, a ₂ = 71.0 × 10^?4 cm^?1).     

Crystal structure of copper(II) <Emphasis Type="Italic">trans</Emphasis>-bis-(4-phenyliminopentan-2-onate)

trans-Bis-(4-phenyliminopentan-2-onato)Cu(II) (5), which is a phenyl-substituted ketoimine, was synthesized, and an X-ray study was performed for this compound. Crystal data for CuN₂O₂C₂₂H₂₄: a = 11.4557(3) Å, b = 26.6845(9) Å, c = 14.2976(5) Å, β = 113.2270(10)°; space group P2₁/n, Z = 8, d _calc = 1.363 g/cm³, R = 0.033. The structure is molecular and built of isolated trans complexes. The central copper atom is surrounded by four atoms (2O+2N) with the average distances Cu-O 1.904(3) Å and Cu-N 1.962(3) Å. The polyhedron around the copper atom is a distorted tetrahedron; the average values of the O-Cu-O and N-Cu-N trans bond angles are 147(2)° and 150(2)°, respectively. The average value of the O-Cu-N angles is 94(1)°.     

Synthesis,crystal structures,and catalytic property of dioxomolybdenum(VI) complexes with hydrazone ligands derived from 3,5-Di-<Emphasis Type="Italic">tert</Emphasis>-butylsalicylaldehyde

Two new dioxomolybdenum(VI) complexes, [MoO₂L¹(MeOH)] (I) and [MoO₂L²] (II), where L¹ and L² are the anionic forms of N'-(2-hydroxy-3,5-di-tert-butylbenzylidene)-4-methoxybenzohydrazide and 2-amino-N'-(2-hydroxy-3,5-di-tert-butylbenzylidene)benzohydrazide, respectively, have been synthesized and characterized by elemental analysis, FT-IR spectra, and single crystal X-ray determination (CF files CCDC nos. 1448089 (I), 1487063 (II)). The crystal of I is monoclinic: space group P21/n, a = 7.353(1), b = 24.758(3), c = 13.891(2) Å, β = 101.013(2)°, V = 2482.3(6) Å3, Z = 4, R ₁ = 0.0848, wR ₂ = 0.2050. The crystal of II is monoclinic: space group P2₁/c, a = 6.752(1), b = 16.947(1), c = 19.510(1) Å, β = 96.891(2)°, V = 2216.5(4) Å3, Z = 4, R ₁ = 0.0670, wR ₂ = 0.1638. The Mo atom in complex I is in octahedral coordination, with three donor atoms of the hydrazone ligand, two oxo groups, and one methanol O atom. The Mo atom in complex II is in square pyramidal coordination, with three donor atoms of the hydrazone ligand, and two oxo groups. The complexes have interesting catalytic properties for sulfoxidation reactions.     

Copper(II) complex with 2-(diphenylacetyl)indanedione-1,3: Synthesis and structure

A copper(II) complex with 2-(diphenylacetyl)indanedione-1,3 (HL) was synthesized. CuL₂·0.5C₄H₈O₂ crystals prepared from chloroform + 1,4-dioxane are triclinic, space group P \(\bar 1\), a = 15.0206(9) Å, b = 16.0132(9) Å, c = 16.8323(10) Å, α = 109.6850(10)°, β = 96.4390(10)°, γ = 97.7120(10)°, Z = 4. A unit cell contains two crystallographically independent centrosymmetric dinuclear complexes of the same structure. Each copper(II) atom is coordinated by bidentate cis-oriented deprotonated ligands L at the corners of the square. Bridging 1,4-dioxane molecules make the CN of each metal atom five.     

Syntheses,characterization, and crystal structures of oxovanadium(V) complexes with similar tridentate hydrazones

Reactions of bis(acetylacetonato)oxovanadium(IV) with N′-[2-hydroxy-4-diethylaminobenzylidene)]-2-methylbenzohydrazide (H₂HMB) and N′-[5-bromo-2-hydroxy-3-methoxybenzylidene)]-2-methylbenzohydrazide (H₂BMB), respectively, produce two oxovanadium(V) species with the formulas [VO(OMe)(HMB)]₂ (I) and [VO(OMe)(HOMe)(BMB)] (II). The complexes have been characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. The crystal of I is triclinic: space group P \(\bar 1\), a = 8.843(1), b = 9.937(1), c = 12.327(2) Å, α = 96.500(2)°, β = 110.070(2)°, γ = 104.220(2)°, V = 962.8(2) ų, Z = 1. The crystal of II is monoclinic: space group P2₁/c, a = 9.908(2), b = 19.968(3), c = 11.065(3), β = 109.362(3)°, V = 2065.3(8) ų, Z = 4. Compound I is the methoxide-bridged dimeric oxovanadium(V) complex, and II is the mononuclear oxovanadium(V) complex. Each V atom in the complexes is in an octahedral coordination.     

Synthesis and crystal structures of the zinc(II) complexes with a tridentate Schiff base (1-pyridin-2-ylethylidene)pyridin-2-ylmethylamine

Two new isostructural zinc(II) complexes, [ZnCl₂(L)] (I) and [ZnBr₂(L)] (II), derived from the Schiff base ligand (1-pyridin-2-ylethylidene)pyridin-2-ylmethylamine (L), have been prepared and characterized by physicochemical methods and single-crystal X-ray crystallography. The crystal of I is monoclinic: space group P2₁/c, a = 11.699(3) Å, b = 8.460(2) Å, c = 14.766(3) Å, β = 99.686(3)°, V = 1440.6(6) ų, Z = 4. The crystal of II is monoclinic: space group P2₁/n, a = 8.166(2) Å, b = 15.153(3) Å, c = 11.966(2) Å, β = 96.964(2)°, V = 1469.7(5) ų, Z = 4. The geometry of the pentacoordinated zinc atoms in both complexes is best described as a square pyramid.