Synthesis,Crystal Structure and Spectroscopic Properties of an Oximato Bridged Cu(II) Dimer

Abstract  

Schiff-base condensation of a equimolar proportion of diacetyl-monoxime monohydrazone and 1-methylimidazole-2-carboxaldehyde in methanol gives rise to the imidazole azine, 3-(1-methylimidazol-2-yl)methylenehydrazonobutan-2-one oxime(HL). Reaction of 1:1 stoichiometric proportion of HL with copper(II)perchlorate hexahydrate in methanol yields a dimeric oximato bridged copper compound, [Cu₂L₂(H₂O)₂](ClO₄)₂ (1). The compound is characterized by C, H and N analyses, FT-IR, ESI–MS, conductivity measurement, UV–Vis spectra and X-ray single crystal diffraction. The title compound (1) crystallizes in the monoclinic space group P2₁/c with a = 6.8533 (8), b = 18.413 (2), c = 11.7399 (14) ?, β = 93.685 (2)°, V = 1478.4 (3) ?³ and Z = 2. The geometry around each copper center is distorted square pyramidal. The copper(II) dimer shows antiferromagnetic interaction mediated by symmetric disposition of oximato groups.     

Synthesis and Crystal Structure of [Cu(BDBPH)(ClO<Subscript>4</Subscript>)<Subscript>2</Subscript>] (BDBPH = Butane-2,3-dione bis(2′-pyridylhydrazone)

Abstract  

Butane-2,3-dione bis(2′-pyridylhydrazone) (BDBPH), a Schiff-base condensate, was synthesized by 1:2 mol ratio condensation of butane-2,3-dione with 2-hydrazino pyridine in dehydrated methanol. BDBPH has been characterised by C, H and N microanalyses, FT-IR, ¹H NMR and UV–Vis spectra. Reaction of 1:1 stoichiometric proportion of BDBPH with copper(II)perchlorate hexahydrate in methanol affords a mononuclear copper(II) complex, [Cu(BDBPH)(ClO₄)₂] (1). 1 crystallizes in the monoclinic space group P [`1] \overline{1} with a = 8.4230(2), b = 9.7869(3), c = 12.3508(3) ?, α = 103.784(2), β = 90.900(2), γ = 94.906(2)^°, V = 984.51(5) ?³ and Z = 2. The copper(II) compound is octahedral and one-electron paramagnetic. Bond Valence Sum (BVS) model calculation was also performed to assign the oxidation number of the copper center.     

Synthesis,Spectroscopic Studies and Structure of 2-[(Benzo[<Emphasis Type="Italic">d</Emphasis>]thiazol-2-ylamino)methyl]phenol

Abstract  

Schiff base (E)-2-[(benzo[d]thiazol-2-ylimino)methyl]phenol (1) has been synthesized from the reaction of 2-hydroxy-benzaldehyde with 2-aminobenzothiazole. The 2-[(benzo[d]thiazol-2-ylamino)methyl]phenol (2) was prepared reduction of the Schiff base 1 with sodium borohydride. The compounds 1 and 2 have been characterized by elemental analysis, FT-IR, ¹H-NMR, ¹³C-NMR and UV–visible spectroscopic techniques. The structure of the compound 2 has also been examined crystallographically. The compound 2 crystallizes in the monoclinic space group P2/c. The unit cell parameters were found as a = 10.017(1), b = 11.725(1), c = 10.341(1) ?, V = 1208.1(1) ?³, D _x = 1.409 g cm⁻³ and Z = 4. The crystal structure was solved by direct methods and refined by the full-matrix least squares method and found as R ₁ = 0.0308 and wR ₂ = 0.0818 for 2032 for the observed reflections [I > 2σ(I)].     

Synthesis and Crystal Structures of Two Novel Complexes with <Emphasis Type="Italic">N</Emphasis>-[2-(5-Bromo-2-Hydroxybenzylideneamino)Ethyl]-4-Methylbenzenesulfonamide as Ligand

Abstract  

Two novel complexes constructed from the sulfonamide Schiff base ligand H ₂ L, N-[2-(5-bromo-2-hydroxybenzylideneamino)ethyl]-4-methylbenzene-sulfonamide, [Cu(HL)₂] (1) and [CuL(H₂O)] (2) are synthesized and characterized via X-ray single-crystal diffraction, elemental analysis, FT-IR and UV–Vis. 1 and 2 both form 1-D supramolecular architectures by π–π stacking interactions. 1 and 2 both crystallize in monoclinic, with space group C2/c and P2/c for 1 and 2, with unit cell parameters a = 27.640(18) ?, b = 7.907(5) ?, c = 17.945(14) ?, β = 118.27(2)°, V = 3454(4) ?³, Z = 4 for 1, and a = 16.758(5) ?, b = 7.272(2) ?, c = 15.080(4) ?, β = 106.334(5)°, V = 1763.6(9) ?³, Z = 4 for 2.     

Synthesis and Structural Characterization of <Emphasis Type="Italic">N</Emphasis>-(2-Pyridylmethyl)-3-Methoxysalicylaldiminato Copper(II) Chloride

Abstract  The copper(II) complex [Cu(C₅H₄NCH₂−N=CH–C₆H₃OCH₃–O)Cl], (1) containing a new tridentate Schiff base ligand (LH), which is the 1:1 condensation product of 2-(aminomethyl)pyridine and o-vaniline, has been synthesised and characterized by IR and UV–Vis spectra. Structural investigation shows that 1 crystallizes to a monoclinic system, having space group P2(1)/c, a = 6.9634(7), b = 18.1209(19), c = 10.3448(11) ?, α = 90°, β = 103.97(2)°, γ = 90° and Z = 4. The coordination geometry around the copper atom is slightly distorted square planar, formed by the N₂O donor set of the Schiff base and one Cl atom. The Cu–N(1), Cu–N(2), Cu–O(1) and Cu–Cl bond distances are 2.0114(14), 1.9414(14), 1.9147(12) and 2.2520(5) ?, respectively. Index Abstract  The copper(II) complex [Cu(C₅H₄NCH₂−N=CH–C₆H₃OCH₃–O)Cl], (1) containing a tridentate Schiff base ligand (LH), synthesised and characterized by IR and UV–Vis spectra. The central copper ion possesses a distorted square-planar geometry.      

Synthesis, Crystal Structure and Density Functional Theory Study of (2-(2-Hydroxyphenyl)benzimidazolate-based Al(III) Complex Cocrystallized by DMF Solvate and Neutral (2-(2-Hydroxyphenyl)benzimidazole

Abstract  

The aluminium(III) complex with 2-(2-hydroxyphenyl)benzimidazole, namely [Al₂(μ-OH)₂L₄)]·6DMF·2HL (1·6DMF·2HL) (HL = 2-(2-hydroxyphenyl)benzimidazole), has been synthesized and characterized by X-ray crystallography. It crystallizes in monoclinic space group C2/c with cell parameters a = 23.6752(13) ?, b = 20.8253(12) ?, c = 18.1645(10) ?, α = 90°, β = 91.929(1)°, γ = 90°, Z = 4, V = 8950.8(9) ?³. The dimeric structure of 1, featuring [Al₂(μ-OH)₂] core has been studied with the density functional theory level (DFT) calculation and molecular orbital analyses.     

Structural and Spectroscopic Study of Cu(II) Pyridine-2,6-dicarboxylate Complex with 2-Ethylimidazole

Abstract  

A mononuclear copper(II) complex, [Cu(pydca)(2-Etlm)(H₂O)] (1) (H₂pydca = pyridine-2,6-dicarboxylic acid, 2-Etlm = 2-ethylimidazole), has been synthesized and characterized by elemental analyses, IR, UV–Vis, TG-DTA and single crystal X-ray diffraction. The complex 1 is in the orthorhombic crystal system, space group Pbca and Z = 8. The structural analysis indicated that Cu(II) center is five coordinated in a slightly distorted square pyramidal geometry by one N and two O atoms from a 2,6-pyridine dicarboxylate dianion, one N atom from a 2-ethylimidazole ligand, and one O atom from a aqua molecule. This mononuclear motif of 1 is further assembled to 3D supramolecular framework through strong O–H···O and N–H···O hydrogen bonding interactions.     

Pyridine-2,6-Dicarboxylic Acid (Dipic): Crystal Structure from Co-Crystal to a Mixed Ligand Nickel(II) Complex

Abstract  

Pyridine-2,6-dicarboxylic acid (dipic) was used for the synthesis of a co-crystal with 1,10-phenanthroline-5,6-dione (phen-dione) and a nickel(II) complex. The co-crystal dipic·phen-dione·4H₂O (1) has been synthesized and studied by X-ray crystallography. The structure is stabilized with hydrogen bonds between dipic, H₂O and phen-dione. It is surprising that there is no direct hydrogen bonding between phen-dione and dipic and yet the molecules co-crystallize in aqueous solution. A new complex of nickel(II), [Ni(phen)(dipic)(H₂O)]·4H₂O (2), (where phen = 1,10-phenanthroline) has been synthesized and characterized by elemental and thermogravimetric analyses, FT-IR, UV–Vis and ¹H-NMR spectroscopy. The structure of (2) has been studied by X-ray crystallography. The coordination around Ni(II) is a distorted octahedron. The crystal packing shows that the dimensionality of (2) is enlarged to 3D, through hydrogen bonds and π–π interactions. Cyclic voltammetry of (2) shows that the Ni(II/I) couple is irreversible.     

Synthesis and Structure of (Bis(1-propylbenzimidazol-2-yl)-trans-1,2-cyclohexane)copper(II) Dichloride and the Structure of a Novel, Unexpected By-Product

Abstract  

Two structures containing the novel ligand bis(1-propylbenzimidazol-2-yl)-trans-1,2-cyclohexane, L, are reported. The first structure, (bis(1-propylbenzimidazol-2-yl)-trans-1,2-cyclohexane)copper(II) dichloride, Cu(II)(L)Cl₂ 1, crystallized in the monoclinic space group P 2₁/n with a = 10.992(4) ?, b = 13.576(5) ?, c = 18.047(7) ?, β = 106.909(8) and V = 2576.7(16) ?³ and Z = 4. Complex 1 exhibits a D _2d-flattened tetrahedral Cu(II)N₂Cl₂ coordination geometry, for which the four-coordinate geometry index τ₄ of 0.59 lies almost midway between the ideal geometry values of zero (square-planar) and 1 (tetrahedral). The second and unexpected structure, (bis(1-hydro-3-propylbenzimidazol-1-ium)-trans-1,2-cyclohexane)(μ⁴-oxo-hexa-(μ²-chloro)-tetra(chloro-copper(II)) di(nitromethane) solvate, 2[H₂L]²⁺[Cu₄OCl₁₀]⁴⁻·(CH₃NO₂)₂, 2, consists of three dimensionally hydrogen bonded bis(benzimidazolium) dications and tetra-copper(II)-oxo-chloride tetra-anions, interspersed with nitromethane solvate molecules. A balanced equation for the formation of the byproduct suggests that it forms via an acid–base reaction in the presence of water in the reaction mixture. The complex crystallized in the triclinic space group P −1 with a = 13.696(3) ?, b = 13.819(3) ?, c = 16.797(4) ?, α = 89.480(4), β = 87.308(4)°, γ = 89.434(4) and V = 3175.3(12) ?³ and Z = 2. Ligand L contains two stereogenic centers, each of the same handedness, and, since the space groups determined for structures 1 and 2 are centrosymmetric, both structures are racemates.     

Structures of Bis(1-ethylbenzimidazol-2-yl)alkyl Copper(II) Dichlorides: An Unusual Cocrystallization

Abstract  Two structures containing pseudo-tetrahedral Cu(II)N₂Cl₂ coordination complexes are reported. The first molecular structure (A) of the compound, 1,1′bis(1-ethylbenzimidazol-2-yl)propane copper(II) dichloride (triEtBBIM)Cu(II)Cl₂, 1, is reported. The complex crystallized in the triclinic space group P-1 with a = 8.616(3) ?, b = 9.302(3) ?, c = 14.314(4) ?, α = 85.613(6)°, β = 85.170(6)°, γ = 66.117(6)° and V = 1044.1(5) ?³ with Z = 2. The second structure (B) contains 1 and (3,3′bis(1-ethylbenzimidazol-2-yl)pentane) copper(II) dichloride (tetEtBBIM)Cu(II)Cl₂, 2, both of which, cocrystallize in an equal molar ratio with a nitromethane solvate molecule. The complex crystallized in the monoclinic space group P2₁/c with a = 18.876(4) ?, b = 14.975(3) ?, c = 18.344(4) ?, β = 116.75(3)°, and V = 4630.3(16) ?³ with Z = 4. The cocrystallization of such discrete complexes has been coined a chemical Janus. Graphical Abstract  The title complexes contain pseudo-tetrahedral Cu(II)N₂Cl₂ coordination. One of the structures is the result of an unusual cocrystallization, in which two different discrete Cu(II) molecules cocrystallize in an equimolar ratio with a nitromethane solvate molecule.      

Spectroscopic Studies and Structure of 4-(3-Benzoylthioureido)benzoic Acid

Abstract  

4-(3-Benzoylthioureido)benzoic acid has been synthesized from the reaction of 4-aminobenzoic acid with benzoyl isothiocyanate. The title compound has been characterized by elemental analysis, MS, FT-IR, ¹H-NMR, ¹³C-NMR and UV–Visible techniques. The structure of the compound has also been examined crystallographically. The title compound crystallizes in the triclinic space group P-1 with a = 3.969(1), b = 13.039(1), c = 13.504(1) ?, α = 96.50(1)°, β = 92.25(1)°, γ = 94.94(1), V = 691.0(1) ?³ and D _x  = 1.444 g cm⁻³, respectively. The crystal structure has been solved by direct methods and refined by full-matrix least squares and found R ₁ = 0.031 and wR ₂ = 0.081 for 2909 observed reflections [I > 2σ(I)].     

Supramolecular Organization in Tetra Aqua (μ-8-Hydroxyquinoline-5-sulfonate) Barium (II) and Ag···I Interactions in a Pseudopolymorphic Form of (7-Iodo-8-hydroxyquinoline-5-sulfonate) Silver (I) Monohydrate

Abstract  

The complexes, Ba (HQS) (H₂O)₄ (HQS = 8-hydroxyquinoline-5-sulfonic acid) (1) and Ag (HIQS) (H₂O) (Ferron = 7-iodo-8-hydroxyquinoline-5-sulfonic acid) (2) have been synthesized and characterized by X-ray diffraction analysis and spectroscopic studies. In compound 1, Ba²⁺ ion has a nine-coordinate monocapped antiprismatic geometry. In compound 2, Ag⁺ has distorted tetrahedral coordination and Ag···I interactions generate the supramolecular architectures. The complexes have been characterized by FT-IR and UV–Visible measurements. In both the structures, the inversion-related organic ligands are stacked over one another leading to three-dimensional networks.     

Spectroscopic Studies and Crystal Structure of (<Emphasis Type="Italic">Z</Emphasis>)-6-[(2-hydroxyphenylamino)methylene]-2-methoxycyclohexa-2,4-dienone

Abstract  The Schiff base (Z)-6-[(2-hydroxyphenylamino)methylene]-2-methoxycyclohexa-2,4-dienone has been synthesized from the reaction of 2-aminophenol with 2-hydroxy-3-methoxybenzaldehyde. The title compound has been characterized by elemental analysis, FT-IR, ¹H-NMR, ¹³C-NMR and UV–Visible techniques. The structure of the title compound also was determined crystallographically. The crystal structure has been solved by direct methods and refined by full-matrix least squares. The title compound crystallize in the monoclinic space group P2₁/c with a = 10.438(1), b = 8.851(1), c = 12.746(1) ?, β = 95.72(1)°, V = 1171.7(2) ?³, D _x  = 1.379 g cm⁻³, respectively (R1 = 0.0522 and wR2 = 0.126 for 1442 reflections [I > 2σ(I)]). Index Abstract   N-salicylideneaniline derivatives have been shown to exist as tautomeric forms due to intramolecular proton shifts between the phenol-oxygen and the imine-nitrogen, via intramolecular hydrogen bonding O–H···N or O···H–N.      

Synthesis and Crystal Structures of Copper(II) Complexes Derived from 5-Methoxy-2-[(2-morpholin-4-ylethylimino)methyl]phenolate and (2-Morpholin-4-ylethyl)-(1-pyridin-2-ylethylidene)amine

Abstract  

A pair of copper(II) complexes, [CuL¹(ONO₂)(OH₂)] 1 and [CuBrL²N₃] 2, where L¹ is 5-methoxy-2-[(2-morpholin-4-ylethylimino)methyl]phenolate, and L² is (2-morpholin-4-ylethyl)-(1-pyridin-2-ylethylidene)amine, have been synthesized and characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. Complex 1 crystallizes in the monoclinic space group P2₁/c, with a = 10.496(2), b = 19.113(3), c = 8.586(2) ?, β = 105.186(10)°. Complex 2 crystallizes in the monoclinic space group C2/c, with a = 16.606(3), b = 7.357(2), c = 26.043(5) ?, β = 94.996(2)°. The Cu atom in each complex is five-coordinate in a square pyramidal geometry.     

Synthesis,Crystal Structure and Fluorescent Study of Bis(2-(2-hydroxyphenyl)benzimidazolate)zinc with Ethanol Solvate

Abstract  The zinc(II) complex with 2-(2-hydroxyphenyl)benzimidazole, namely [Zn(2-(2-hydroxyphenyl)benzimidazolate)₂]·C₂H₅OH (1 · C₂H₅OH) has been synthesized and characterized by X-ray crystallography and photoluminescent analysis. The complex crystallizes in monoclinic space group P2₁/c with cell parameters a = 10.156(1) ?, b = 25.771(3) ?, c = 9.674(1) ?, α = 90°, β = 103.641(2)°, γ = 90°, Z = 4, V = 2460.4(4) ?³. The central Zn(II) is four-coordinate and has a tetrahedral geometry. The steady-state and time-resolved photoluminescent spectra for the title compound have also been studied. The emission property can be ascribed to ligand-centered charge-transfer transition (LCCT) with π → π* property. Index Abstract   A new co-crystal of Zn(II) complex of 2-(2-hydroxylphenyl)benzimidazole with ethanol solvate has been prepared, characterized by X-ray crystallography and fluorescent studies.      

Synthesis, Molecular Structure and Antioxidant Activity of (E)-4-[Benzylideneamino]-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one, a Schiff Base Ligand of 4-Aminoantipyrine

Abstract  

In this study, the title compound, C₁₈H₁₇N₃O (M _r = 291.35), was synthesized by the condensation reaction of 4-amino-1,5-dimethyl-2-phenylpyrazole-3-one and benzaldehyde. Single-crystal X-ray diffraction data revealed that this compound adopts a trans configuration around the central C=N double bond. It crystallizes in the monoclinic, space group P2₁/c with a = 12.9236(17) ?, b = 6.8349(9) ?, c = 17.072(2) ?, β = 90.316(3)°, V = 1508.0(3) ?³, Z = 4, D _c = 1.283 Mg/m³, F(000) = 616, μ = 0.082 mm⁻¹, R = 0.0442, and wR = 0.0936. Two different planes exist within the molecule; e.g. the pyrazolone and benzylidene groups attached to C9 of the pyrazolone ring are almost coplanar, whereas the phenyl group attached to the N1 of the pyrazolone ring is in another plane. Density functional theory (DFT) and time-dependent DFT calculations were performed to predict the electronic structure and absorption spectra of (E)-4-[benzylideneamino]-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one, a schiff base ligand of 4-aminoantipyrine using B3LYP/6-311G basis set on the AM1 optimized geometry. The predicted vibrational frequencies using the B3LYP/6-311G method were in strong agreement with the experimental IR spectra. The time dependent DFT calculations were used to evaluate the electronic absorption spectrum and three electron transition bands, which were mainly derived from the contribution of n → π* and π → π* transitions, were observed in both the experimental and predicted UV–Vis spectra. A maximum emission band at 370 nm was observed in the fluorescence spectra of the title compound. In addition, the title compound showed good DPPH antioxidant activity.     

Synthesis,Characterization, Structure,Ab Initio and DFT Calculations of 2-Amino-<Emphasis Type="Italic">N</Emphasis>-(3-phenylprop-2-enylidene)aniline

Abstract  

New Schiff base compound 2-amino-N-(3-phenylprop-2-enylidene)aniline, 1, was prepared by condensation of cinnamaldehyde with o-phenylenediamine and characterized by elemental analyses, UV–Vis and FT-IR spectroscopy. The crystal structure of 1 was determined by X-ray crystallography from single-crystal data and displays a trans configuration about the C=N double bond. In the crystal structure of 1, the molecule is located on an inversion center, so that it is disordered around the center of central C–C bond. The results from both the experimental and theoretical calculations are compared in this paper.     

Crystallographic and Computational Analysis of the Supramolecular Structure of 2,5-Dimethylpyrazolo[1,5-a]pyrimidin-7(4H)-one

Abstract  

The structure of 5-dimethylpyrazolo[1,5-a]pyrimidin-7(4H)-one 1 has been determined by X-ray crystallography. The compound 1 crystallizes in the space group P−1 with two molecules in the asymmetric unit solvated with one molecule of the acetic acid The unit cell parameters are a = 8.796(1) ?, b = 10.531(1) ?, c = 10.680(1) ?, α = 96.901(2)o, β = 98.135(2)o, γ = 107.248(2)o. In the crystal molecules A and B are linked into R ₂²(9) hydrogen bonded rings and these rings form chains parallel to [101] Overall, the supramolecular structure 1 consists of two hydrogen bonded and two π–π stacking dimers. An energetic interplay between these dimers has been studied using B3LYP DFT calculations. In addition π–π interactions are analyzed using the Bader’s atoms in molecules’ (AIM) theory.     

A Neutral Four-Coordinate Mononuclear Cobalt(II) Complex with Biphenyl Appended N-Bidendate Ligand: Synthesis, Structure and Spectral Properties

Abstract  

A mononuclear cobalt(II) complex [Co(BP)(Cl₂)], 1 with a new N,N-bidentate ligand, BP ([N,N-(1,1′-biphenyl-2,2′-dimethylene)]-2-aminomethyl) pyridine) was synthesized and characterized by elemental analysis, UV–Vis, paramagnetic NMR, magnetic moment and single crystal XRD. The air and moisture stable Co(II) title complex is a 15 electron species which crystallizes in the monoclinic space group P2₁/n with cell dimensions a = 10.406(3), b = 12.873(4), c = 13.859(7) ?, β = 96.30(3)˚ and Z = 4. The cobalt atom has distorted tetrahedral (td) geometry with coordination provided by an amine and pyridyl nitrogen donors of BP and two terminal chloride ions. The packing is stabilized through C–H···π and van der Waals interactions.     

Synthesis and Crystal Structure of Phenolato-Bridged Dinuclear Copper(II) Complex with (2-Hydroxybenzyl)(2-pyridylmethyl)amine

Abstract  

The tridentate Schiff base phenol-containing ligand (2-hydroxybenzyl)(2-pyridylmethyl)amine (Hbpa) reacts with copper(II) perchlorate to give the phenolato-bridged dinuclear complex [Cu(bpa)(H₂O)]₂·2ClO₄ (1). Each copper(II) ion exhibits a distorted square-pyramidal environment, being coordinated by two nitrogen atoms and two phenolato oxygen atoms of the two deprotonated bpa ligands, and one oxygen atom of the water molecule. It crystallizes in the triclinic system P-1 with a = 7.8790(6), b = 8.9345(7), c = 12.0207(9) ?, α = 69.158(1), β = 85.307(1), γ = 76.629(1)°, V = 769.39(10) ?³, Z = 1. Cyclic voltammetry of 1 gives two oxidation and two reduced processes.