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.      

Molecular and Crystal Structure of 2-{(<Emphasis Type="Italic">E</Emphasis>)-[(5-Chloro-2-methoxyphenyl)imino]methyl}-4-nitrophenol

The molecular structure of the title compound, C₁₄H₁₁ClN₂O₄, was determined by single crystal X-ray diffraction. The compound crystallizes in the monoclinic sp. gr. P2₁/c with Z = 4. The title compound, C₁₄H₁₁ClN₂O₄, is a Schiff base which adopts the phenol-imine tautomeric form in the solid state.The molecule is almost planar and the dihedral angle between the planes of two aromatic ring is 2.2(1)°. The molecular structure is stabilized by intramolecular O–H···N hydrogen bond which generates a six-membered ring. In the crystal structure, the molecules are linked together by intermolecular C–H···O interactions.     

Crystallographic and Conformational Analysis of [(<Emphasis Type="Italic">E</Emphasis>)-2-[(3-Chlorophenylimino)methy])-4-methoxyphenol]

Abstract  The crystal structure of C₁₄H₁₂ClNO₂ was determined by X-ray analysis. It crystallizes in the triclinic space group Pc with a = 12.5346(10) ?, b = 4.5101(3) ?, c = 12.0534(11) ?, α = 90.00o, β = 113.669(6)o, γ = 90.00o, Z = 2, Dx = 1.393 mg/m³, μ (MoK_α) = 0.298 mm⁻¹. The title compound is photochromic and molecule is non-planar. It adopts a phenol–imine tautomeric form with a strong intramolecular O–H···N hydrogen bond and a strong intermolecular C–H···O hydrogen bond. Minimum energy conformations AM1 were calculated as a function of the three torsion angles θ1(C10–C9–N1–C8), θ2(C9–N1–C8–C1) and θ3(N1–C8–C1–C6), varied every 10°. As in the X-ray experiment results, molecule has an angle that makes it non-planar between two aromatic rings in AM1 optimized geometry. Graphical Abstract  Molecular and crystal structure of [(E)-2-[(3-chlorophenylimino)methy])-4-methoxyphenol], C₁₄H₁₂ClNO₂, have been determined by single crystal X-ray diffraction study, and conformational analysis of the title molecule with respect to the selected torsion angle has been achieved by AM1 semi-empirical calculations.      

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.      

Molecular and crystal structure of 2-{(<Emphasis Type="Italic">E</Emphasis>)-[(4-Methylphenyl)imino]methyl}-4-nitrophenol: A redetermination

The crystal structure of the title compound, C₁₄H₁₂N₂O₃, was recently determined as a mixture of its neutral (OH containing) and zwitterionic (NH containing) forms, in a 0.60 (4): 0.40 (4) ratio using the X-ray determination. In this study, the title compound has been characterized by FT-IR and X-ray diffraction. The redetermination showed that the title compound has only enol (OH) form because of lack of the NH stretching vibration in FT-IR spectrum. In addition, the molecular structure and tautomerism of the title compound have been discussed.     

Two Crystal Forms of 4-{(2<Emphasis Type="Italic">E</Emphasis>)-2-[1-(4-Methoxyphenyl)ethylidene] hydrazinyl}-8-(trifluoromethyl)quinoline

Abstract  

The Schiff base, 4-{(2E)-2-[1-(4-methoxyphenyl)ethylidene] hydrazinyl}-8-(trifluoromethyl)quinoline, crystallizes in two polymorphic forms depending on the solvent. One of these forms is monoclinic (1M), space group P2₁/c with a = 10.2906(10) ?, b = 8.9211(7) ?, c = 18.4838(15), β = 97.271(8)°, and the other is orthorhombic (1O), space group Pbca, unit-cell parameters: a = 13.6485(12) ?, b = 9.0588(9) ?, c = 27.400(2) ?. The molecules in either crystalline form have similar bond lengths and angles, but one is nearly planar while the other has a significant twist. In monoclinic form the dihedral angle between terminal ring planes is 17.26(8)° while in the orthorhombic one it is 26.11(5)°, and in this latter case the central chain is almost coplanar with the quinoline ring system while in the former these two planes are significantly twisted. The crystal structures of both forms are determined by the interplay of van der Waals forces and weak directional interactions C–H···F, π···π stacking, and—in the case of 1M—short intermolecular C–F···N contact. The crystals of 1M decomposes slowly into the powder while the other form is stable. The powder diffraction pattern of the product of decomposition of 1M is similar to that calculated for 1O. This suggests that the decomposition is a consequence of the phase transition of the less stable monoclinic into more stable orthorhombic form.     

Crystallographic and conformational analyses of zwitterionic form of (<Emphasis Type="Italic">E</Emphasis>)-2-methoxy-6-[(2-morpholinoethylimino)methyl]phenolate

The single crystal X-ray diffraction analysis of the title compound, C₁₄H₂₀N₂O₃, reveals that the structure is adapted to its zwitterionic form and centrosymmetric dimers are formed by N⁺–H···O⁻ type ionic weak hydrogen bonds in the crystal structure. The title compound crystallizes in the triclinic space group P−1 with a = 5.9255(13) ?, b = 9.853(3) ?, c = 12.248(3) ?, α = 101.793(19)°, β = 94.941(17)°, γ = 104.36(2)°, Z = 2, D_x = 1.308 g/cm³, μ (Mo-K_α) = 0.092 mm⁻¹. The structure was solved by direct methods and refined to a final R = 0.0371 for 2183 reflections with I > 2σ (I). The crystal structure is stabilized by N⁺–H···O⁻ type intra-molecular hydrogen bonds and N⁺–H···O⁻ type packing interactions referred to as weak hydrogen bonds. To elucidate conformational flexibility of the title molecule, the selected torsion angle is varied from −180° to +180° in every 10° separately and then molecular energy profile is calculated and construed. In addition, charge-population analysis of the crystallographically observed structure confirms its zwitterionic form.     

Synthesis of <Emphasis Type="Italic">E</Emphasis> Isomer and Crystal Structures of <Emphasis Type="Italic">E</Emphasis> and <Emphasis Type="Italic">Z</Emphasis> Isomers of 3-(2,5-Dimethoxyphenyl)-2-(4-methoxyphenyl)acrylonitrile

Abstract Details of the synthesis of the E isomer of 3-(2,5-dimethoxyphenyl)-2-(4-methoxyphenyl)acrylonitrile, and the X-ray crystal structures of both the E and Z isomers of this compound are presented. The E isomer crystallizes in the P2₁/c space group with cell parameters, a = 8.5659(17) ?, b = 16.399(3) ?, c = 11.224(2) ?, α = 90°, β = 95.27(3)°, γ = 90°and Z = 4. The Z isomer crystallizes in the Pca2₁ space group with cell parameters, a = 4.1223(8) ?, b = 19.113(4) ?, c = 19.453(4) ?, α = 90°, β = 90°, γ = 90° and Z = 4. Index Abstract Synthesis of E isomer and X-ray crystal structure determination of both E and Z isomers of 3-(2,5-dimethoxyphenyl)-2-(4-methoxyphenyl)acrylonitrile are presented.      

Synthesis and Crystal Structure of Bis[<Emphasis Type="Italic">N</Emphasis>-{(<Emphasis Type="Italic">S</Emphasis>)-1-Phenylethyl}-<Emphasis Type="Italic">N</Emphasis>-{1-(2-Pyridinyl)Methyl}Amine] Zinc(II) Perchlorate

Abstract  

The reaction of N-[(S)-1-phenylethyl]-N-[1-(2-pyridinyl)methyl]amine (PEPMA) with Zn(ClO₄)₂ affords (PEPMA)₂Zn(ClO₄)₂ at room temperature. The complex is characterized by elemental analysis, ¹H-MNR and X-ray crystallography. The crystal system is orthorhombic with space group of P2₁2₁2₁ and unit cell parameters: a = 8.6911(4), b = 9.7755(7), c = 37.275(2) ?, V = 3166.9(3) ?³, Z = 4, D _x  = 1.445 Mg/m³. The crystal structure reveals that zinc metal is ligated by two PEPMA ligands in a distorted tetrahedral fashion. Interestingly, both nitrogen atoms of amine at PEPMA to the central zinc metal exhibit (R)-configuration.     

Synthesis,Spectroscopic and Crystal Structure Analysis of <Emphasis Type="Italic">N</Emphasis>-[imidazolidin-2-ylidene]-5-(thien-2-yl)[1,3,4]thiadiazole-2-amine

The crystal structure of the title compound has been determined. The compound crystallizes in the monoclinic space group P2₁/c with a = 5.9885(2) Å, b = 14.7345(4) Å, c = 12.3719(4) Å, β = 96.655(5)°, V = 1084.31(8) Å³, z = 4. An intramolecular N–H···N hydrogen bond forms a pseudo-six-membered ring with graph set S ¹ ₁(6). The crystal structure is stabilized by intermolecular interactions of the type N–H···N and C–H···N. The packing motifs in accordance with Etter’s analysis are R ² ₂(8) corresponding to N–H···N dimer and that generated by the chain is C(7).     

Synthesis and Crystal Structure of Chiral Substituted (<Emphasis Type="Italic">S</Emphasis>)-2-[(<Emphasis Type="Italic">4</Emphasis>-Methoxyphenoxy) Methyl]-15-Crown-5 Ether with Sodium Perchlorate Complex

Abstract  The crystal and molecular structure of chiral crown ether, (S)-2-[(4-methoxyphenoxy)methyl]-15-crown-5 · NaClO₄, has been determined by single-crystal X-ray diffraction. The complex crystallizes in the orthorombic space group Pbca with Z = 8. Lattice parameters are a = 11.451(2), b = 12.842(3), c = 31.330(7) ?. The structure was refined to R factor of 0.0547. The Na ion is heptacoordinated. The Na–O_ether distances range from 2.363(4) to 2.433(4) ? and average 2.404(5) ?. Perchlorate anion is bounded to sodium ion asymmetrically; the Na–O8 and Na–O9 distances are 2.444(5) ? and 2.607(5) ?. The C–O and C–C distances of the 15-membered ring average 1.419(9) and 1.478(12) ? while the O–C–C and C–O–C angles average 108.2(6)˚ and 115.4(6)˚. Index Abstract  In the molecule, the sodium ion is seven coordinated by the five ring oxygen atoms and two oxygen atoms of the perchlorate anion. The macrocyclic strand of the molecule displays ag-a, ag+a, ag−a, ag+a, ag−g-set of torsion angles.      

Structural Features of <Emphasis Type="Italic">Ortho</Emphasis>-hydroxy Bis-phenols and Their Comparison with <Emphasis Type="Italic">Para</Emphasis>-hydroxy Bis-phenols

Abstract The crystal structures of four bis-phenols are reported to substantiate the fact that the weak interactions play a major role in the crystal packing of bis-phenols. The reaction of 2,4-dimethylphenol with aldehydes such as 2-naphthaldehyde, terephthaldehyde in the presence of trifluoracetic acid gave 2-[bis(2-hydroxy 3,5-dimethylphenyl)methyl]naphthalene (1) and 4-[bis(2-hydroxy 3,5-dimethylphenyl) methyl]benzaldehyde (2), respectively. The 2-[bis-(2-hydroxy 3,5-dimethylphenyl)-methyl]naphthalene (1) crystallizes in orthorhombic, Pbca, a = 11.905(3) ?, b = 18.788(5) ?, c = 18.894(5) ?, 4-[bis(2-hydroxy 3,5-dimethylphenyl)methyl] benzaldehyde (2) in monoclinic, Cc, a = 8.880(3) ?, b = 16.394(7) ?, c = 13.700(5) ?, γ = 104.542(2)°. The reaction of 2-nitrobenzaldehyde with 2,4-dimethylphenol gave 2-benzo[c] isoxazo-3-yl 4,6-dimethylphenol (3) and its crystal parameters are orthorhombic, P2₁2₁2₁, a = 7.737(6) ?, b = 11.885(9) ?, c = 13.336(8) ?. The reaction of 2,6-dimethylphenol with 4-nitrobenzaldehyde and 2-chlorobenzaldehyde gave bis(4-hydroxy 3,5-dimethylphenyl)(4-nitrophenyl)methane (4) and bis(4-hydroxy 3,5-dimethylphenyl)(2-chlorophenyl)methane (5), respectively. The bis(4-hydroxy 3,5dimethylphenyl)(4-nitrophenyl)methane (4) crystallizes in monoclinic, C2/c, a = 25.921(1) ?, b = 12.202(4) ?, c = 15.6084(7) ?, β = 122.172(4)°, and bis(4-hydroxy 3,5-dimethylphenyl) (2-chlorophenyl)methane crystallizes as acetonitrile solvate (5) in triclinic, P-1, a = 12.314(3) ?, b = 14.111(3) ?, c = 15.078(5) ?, α = 98.268(2)°, β = 111.268(2)°, γ = 114.304(1)˚. The unit cell of 5 contains two pairs of crystallographically unsymmetric molecules of bis-phenols. Index abstract The crystal structures of four bis-phenols are reported to substantiate the fact that the weak interactions plays a major role in crystal packing and can induce symmetry non-equivalence among bis-phenols in unit cell of bis-phenols.      

Spectroscopic Studies and Crystal Structure of 3-[(2-morpholinoethylimino)methyl]benzene-1,2-diol

Abstract Schiff base 3-[(2-morpholinoethylimino)methyl]benzene-1,2-diol has been synthesized from the reaction of 4-(2-aminoethyl)morpholine with 2,3-dihydroxybenzaldehyde. The title compound has been characterized by elemental analysis, IR, ¹H-NMR, ¹³C-NMR and UV–visible techniques. The structure of the compound also has been examined crystallographically. For the compound exist as dominant form of enol-imines in both the solutions and solid state. 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/n with a = 12.085(1), b = 8.256(1), c = 13.650(1) ?, β = 108.56(1)°, V = 1291.1(2) ?³, D _x = 1.288 g cm⁻³, respectively (R ₁ = 0.0336 and wR ₂ = 0.0922 for 2117 reflections [I > 2σ(I)]. Index abstract Intramolecular hydrogen bonding is important on the tautomeric properties and the type of aldehyde plays a vital role of the enol-imine and keto-amine properties of the Schiff base ligand.      

Experimental and Semi-Empirical and DFT Calculational Studies on (<Emphasis Type="Italic">E</Emphasis>)-2-[(2,4-Dichlorophenylimino) methyl]-<Emphasis Type="Italic">p</Emphasis>-cresol

Abstract  

The molecular and crystal structure of the title compound, C₁₄H₁₁Cl₂NO, has been determined by X-ray single crystal diffraction technique. The compound crystallizes in the orthorhombic, space group Pbca with unit cell dimensions a = 7.5537(10) ?, b = 11.5518(13) ?, c = 29.760(4) ?, M _r  = 280.14, V = 2596.8(6) ?³, Z = 8, R ₁ = 0.065 and wR ₂ = 0.191. The title compound exists in the enol–imine tautomeric form with a strong intramolecular O–H···N hydrogen bond. The dihedral angle between the two benzene rings is 37.66(15)°. The asymmetric unit in the crystal structure contains only one neutral molecule. Calculational studies were performed by using AM1, PM3, PM6 semi-empirical and DFT methods. Geometry optimizations of compound have been carried out by using three semi-empirical methods and DFT method and bond lengths, bond and torsion angles of title compound have been determined. Dipole moments (Debye) and the energy parameters of compound (kcal/mol) were calculated by using above mentioned calculation methods. Atomic charge distribution has been obtained from AM1, PM3, PM6 and DFT. In order to determine conformational flexibility on the molecule, molecular energy profile of the title compound was obtained with respect to the selected torsion angle T(N1–C7–C1–C2), which is varied from −180° to +180° in every 10 via PM3 semi-empirical method.     

Synthesis and Crystal Structure of a New Schiff Base 4-[(2-hydroxy-benzylidene)-amino]-<Emphasis Type="Italic">N</Emphasis>-(5-methyl-isoxazol-3-yl)-benzenesulfonamide

Abstract  The structure of the title compound (C₁₇H₁₅N₃O₄S)₂ the schiff base, bis(N-(5-methyl-3-isoxazolyl)-4-[(2-hydroxy benzylidene)-amino]) benzene sulfonamide was elucidated by H¹, C¹³ NMR, UV–VIS and IR spectroscopic techniques. The X-ray structure was determined in order to establish the conformation of the molecule. The compound crystallizes in the triclinic space group P-1, with a = 11.419(1), b = 11.426(0), c = 13.316(1) ?, α = 71.94(2), β = 89.79(1), γ = 89.14(2)° and Z = 4. Two benzene rings and azomethine group are practically coplanar, as a result of intramolecular hydrogen bonds involving the hydroxy O atom and azomethine N atom. The component species further interact via N–H···N and C–H···O hydrogen bonds and π–π stacking interactions. Index Abstract  The title compound (C₁₇H₁₅N₃O₄S)₂, Schiff base, bis(N-(5-methyl-3-isoxazolyl)-4-[(2-hydroxy benzylidene)-amino]) benzene sulfonamide was synthesized by the condensation of 4-amino-N-(5-methyl-3-isoxazolyl) benzene sulfonamide (SMZ) and 2-hydroxy benzaldehyde (SA). Its structure was confirmed by single crystal X-ray diffraction analysis. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Desynchronization of Pedal Motion: Crystallographic and Theoretical Study of (<Emphasis Type="Italic">E</Emphasis>)-4-[(4-ethylphenyl)diazenyl]-2-methylphenol

Abstract  The single crystal X-ray diffraction analysis of the title compound, C₁₅H₁₆N₂O, reveals that its molecules exhibit whole-molecule disorder at both crystal lattice sites due to pedal motion in solid state. The compound crystallizes in the monoclinic space group P 2₁/c with a = 20.5504(14) ?, b = 10.8887(5) ?, c = 12.0191(8) ? and β = 96.927(5)°. While major pedal conformers of the compound in solid state are stabilized by intermolecular O–H···N type hydrogen bonds leading to the formation of C(7) chains at Site 1 and C(8) chains at Site 2 along [0 1 0] axis, C–H···π type intermolecular interactions between major and minor conformers also serve to stabilize minor pedal conformers. An interesting feature about the crystal structure is that pedal conformers at Site 1 have two different occupancy factors arising from desynchronization of pedal motion along [2 1 0] direction in crystal phase. Quantum chemical calculations at the B3LYP/6-31++G** level suggest that the desynchronization of pedal motions make more unstable pedal conformers at Site 1 than those at Site 2. Index Abstract  Molecular and crystal structure of (E)-4-[(4-ethylphenyl)diazenyl]-2-methylphenol, C₁₆H₁₈N₂O, indicate desynchronization of pedal motion and the quantum chemical calculations at level of B3LYP/6-31++G** suggest that desynchronization of pedal motions make more unstable pedal conformers.      

Synthesis and structure of chiral ligand [(<Emphasis Type="Italic">S</Emphasis>)-1-(((<Emphasis Type="Italic">S</Emphasis>)-1-methylpyrrolidin-2-yl) methyl) pyrrolidin-2-yl] diphenylmethanol

The title compound (C₂₃H₃₀N₂O), a chiral ligand, has been successfully synthesized from a natural proline. FTIR spectrum has been discussed. DFT (B3LYP) method has been used to determine the structure. With the basis set of the 6–311G^* quality, the DFT calculated bond parameters and harmonic vibrations are predicted in very good agreement with experimental data.

(<Emphasis Type="Italic">E</Emphasis>)-2-[(2-Bromophenylimino)methyl]-5-methoxyphenol: X-ray and DFT-calculated structures

The crystal structure of (E)-2-[(2-Bromophenylimino)methyl]-5-methoxyphenol is determined by using X-ray diffraction and then the molecular structure is investigated with density functional theory (DFT). X-Ray study shows that the title compound has a strong intramolecular O-H…N hydrogen bond and three dimensional crystal structure is primarily determined by C-H…π and weak van der Waals interactions. The strong O-H…N bond is an evidence of the preference for the phenol-imine tautomeric form in the solid state. Optimized molecular geometry is calculated with DFT at the B3LYP/6-31G(d,p) level. The IR spectra of compound were recorded experimentally and calculated to compare with each other. The results from both experiment and theoretical calculations are compared in this study.     

Crystal Structure of 2-((<Emphasis Type="Italic">E</Emphasis>)-(5-Bromo-2- hydroxybenzylidene)hydrazono)-1,2-diphenylethanone

The molecular structure of the title compound, C₂₁H₁₅Br₁N₂O₂, was characterized by single crystal X-ray diffraction. The compound crystallizes in the triclinic sp. gr. \(P\bar 1\) with Z = 2. The molecule is not planar: the dihedral angle between the planes of two aromatic rings [C1/C6] and [C16/C21] is 84.9(2)°. The other dihedral angle between two aromatic rings [C9/C14] and [C16/C21] is 88.8(2)°. The title compound exists as a phenol-imine tautomer, in which a strong intramolecular O–H···N hydrogen bond is formed. This study verifies the preference of the phenol-imine tautomeric form in the solid state. A π–π stacking interactions are also observed, which may influence crystal stability: the distance between centroids is 3.702(2) Å.     

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)].