Synthesis and Crystal Structure of Heptyl 3-(3,4-dihydroxyphenyl)-2-propenoate

Abstract  The title compound, C₁₆H₂₂O₄, synthesized by modified Knoevenagel condensation of protocatechualdehyde with monoheptyl-malonate and recrystallized from benzene, was confirmed by single-crystal X-ray diffraction (CCDC 272827). The compound crystallizes in triclinic space group Pī with cell parameters a = 5.296(3) ?, b = 10.711(13) ?, c = 13.870(4) ?, α = 98.84(7)°, β = 90.97(4)°, γ = 96.77(7)° and Z = 2. The structure is the E isomer and its packing is stabilized by intermolecular O–H···O and C–H···O hydrogen bonds. Index Abstract  The title compound, C₁₆H₂₂O₄, synthesized by modified Knoevenagel condensation, was confirmed by single-crystal X-ray diffraction showing its structure is in E isomer and its packing is stabilized by hydrogen bonds.      

Synthesis, Crystal Structure, Thermal Behavior and IR Characterization of Pentacarbonyl(4-methylpyridine)chromium(0) Complex

Abstract  Pentacarbonyl(4-methylpyridine)chromium(0) complex was isolated from n-hexane solution as yellow plate-like crystals and characterized by using X-ray crystallography. It crystallizes in the orthorhombic system with the space group Cmcm and Z = 4. The unit cell parameters are a = 11.737(1) ?, b = 12.857(2) ?, c = 8.465(1) ?. The single crystal X-ray structure of the complex shows that the coordination sphere around the chromium central atom is slightly distorted octahedron, involving the 4-methylpyridine (4-mp), ligand as a monodentate N-donor ligand and five carbonyl groups. The four equatorial CO groups in the complex, with the Cr–C2 distance of 1.886 Ǻ, are slightly bent away from the 4-methylpyridine ligand with the N–Cr–C2 angle of 91.69°. The pyridine ring plane makes an angle of 135.17° with the Cr–N–CO bond axis. The thermal analysis (differential thermal analysis and thermal gravimetry) and IR spectra of the complex indicated that the compound undergoes complete decomposition to form the Cr₂O₃ as the final decomposition product. Index Abstract  The crystal structure of pentacarbonyl(4-methylpyridine)chromium(0) complex has been determined and its thermal behavior has also been studied.      

Synthesis and Crystal Structure of a New Mo(V) Complex of Cyano Ligands

Abstract  A new complex, [H₃teta][Mo(CN)₈] · H₂O, (teta = 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetra-azacyocloteradeca-4,11-diene), has been synthesized and characterized by IR spectrum, element analysis and single crystal X-ray diffraction: monoclinic, space group P2(1)/c with a = 10.8553(8) ?, b = 12.4854(8) ?, c = 22.6348(15) ?, α = 90.00°, β = 97.3080(10)°, γ = 90.00°, Mr = 609.63, v = 3042.8(4), Z = 4. There are one [H₃teta]³⁺, one [Mo(CN)₈]³⁻ and one water molecule in the asymmetric unit. The complex is interconnected through hydrogen bond and formed into a 3D porous network. Graphical Abstract  A new complex, [H₃teta][Mo(CN)₈] · H₂O, has been synthesized and characterized by IR spectrum, element analysis and single crystal X-ray diffraction. And it shows a 3D porous network through hydrogen bonds.      

Synthesis and Structure of a CdI<Subscript>2</Subscript> Coordination Polymer with 1,4-Bis(benzimidazole-1-yl-methylene)benzene (bbmb)

Abstract  In this paper, solution reaction of cadmium iodide with organic multifunctional ligand 1,4-bis(benzimidazole-1-yl-methylene)benzene generated a 1D polymer [CdI₂ (bbmb). (DMF) (CH₃CN)]_n 1, and the crystal structure has been determined (C₂₇H₂₈CdI₂N₆O), Mr = 818.75, a  = 14.929(1) ?, b = 17.381(2) ?, c = 15.850(1) ?, β = 114.8190(10)°, space group C2/c, Z = 4, and V = 3733.3(6) ?³. In 1 the tetrahedral coordination of Cd(II) and the conformation of the bbmb ligand make it a wave-shaped structure.

---

Graphical Abstract  Synthesis and structure of a CdI2 coordination polymer with 1,4-bis(benzimidazole-1-yl-methylene)benzene(bbmb) Xiucun Liu, Xiaoling Guo, Yunyin Niu, Qingli Wang, Qian Cui, Hongwei Hou, Xiaorui Lv, SeikWeng Ng Solution reaction of cadmium iodide with organic multifunctional ligand 1,4-bis(benzimidazole-1-yl-methylene)benzene (bbmb) generated a 1D polymer [CdI₂ (bbmb) (DMF)(CH₃CN)]_n, in which the tetrahedral coordination of Cd(II) and the conformation of bbmb ligand make it a wave-shaped structure.

     

Synthesis and Crystal Structures of Ternary Copper(II) Complex Containing Salicylaldehyde Schiff Base and 4,4′-Bipyridine

Abstract  A new ternary mixed-ligand complex [Cu₂(sal-glu)₂(bipy)(H₂O)₂] · (H₂O) (bipy = 4,4′-bipyridine and sal-glu = salicylaldehyde l-glutamic Schiff base) has been synthesized and characterized by X-ray diffraction. It crystallizes in the triclinic system, space group P-1 with a = 9.6199(13) ?, b = 9.9111(13) ?, c = 9.9167(13) ?. The amino acid Schiff base coordinates to the Cu(II) ion in a tridentate mode including phenol-hydroxyl oxygen, carboxyl oxygen and amide nitrogen atom, while the bipy coordinates in bidentate bridging mode linking two Cu(II) ions. The [Cu₂(sal-glu)₂(bipy)(H₂O)₂] units are linked into 1-D chain structure and the bipy molecules are interspersed into parallel sheets via intermolecular hydrogen bonds. The carboxyl oxygen atoms, phenolic oxygen atoms and water oxygen atoms are involved in the extensive intermolecular hydrogen bond network between the water molecules and phenol-hydroxyl oxygen atoms from salicylaldehyde derived ligand. Graphical Abstract  A new ternary mixed-ligand complex [Cu₂(sal-glu)₂(bipy)(H₂O)₂]·(H₂O) (bipy = 4, 4′-bipyridine and sal-glu = salicylaldehyde l-glutamic Schiff base) crystallizes in the triclinic system, space group P-1 with a = 9.6199(13) ?, b = 9.9111(13) ?, c = 9.9167(13) ?. The amino acid Schiff base coordinates to the Cu(II) ion in a tridentate mode including phenol-hydroxyl oxygen, carboxyl oxygen and amide nitrogen atom, while the bipy coordinates in bidentate bridging mode linking two Cu(II) ions. The [Cu₂(sal-glu)₂(bipy)(H₂O)₂] units are linked into 1-D chain structure and the bipy molecules are interspersed into parallel sheets via intermolecular hydrogen bonds. The carboxyl oxygen atoms, phenolic oxygen atoms and water oxygen atoms are involved in the extensive intermolecular hydrogen bond network between the water molecules and phenol-hydroxyl oxygen atoms from salicylaldehyde derived ligand.      

Complementary Supramolecular Aggregation via O–H···O Hydrogen-bonding and Hg···S Interactions in Bis[N,N′-di(2-hydroxyethyl)-dithiocarbamato-S,S′]mercury(II): Hg[S2CN(CH2CH2OH)2]2

Abstract  The central mercury atom in Hg[S₂CN(CH₂CH₂OH)₂]₂ is asymmetrically chelated by two dithiocarbamate ligands leading to a distorted square planar geometry. Molecules aggregate into supramolecular chains via Hg···S interactions that are connected into a three dimensional array by extensive hydrogen bonding interactions. The compound crystallizes in the orthorhombic space group Pna2₁ with a = 13.8173(7) ?, b = 4.5307(1) ?, c = 26.0261(12) ?, and Z = 4. Index Abstract  Molecules associate into supramolecular chains via Hg···S interactions and these are connected into a three dimensional architecture by O–H···O hydrogen-bonding interactions.      

The Preparation, Characterization and X-ray Structural Analysis of Tetrakis[1-Methyl-3-(2-Propyl)-2(3H)-Imidazolethione]Cadmium(II) Hexafluorophosphate

Abstract  A new compound, [Cd(mipit)₄][PF₆]₂ has been synthesized and characterized via standard solid and solution state methods including single crystal X-ray crystallography (mipit = 1-methyl-3-(2-propyl)-2(3H)-imidazolethione). The title compound crystallizes in tetragonal space group I4 ₁ /a with a = 12.478(2) ?, b = 12.478(2) ?, c = 28.806(6) ?, and Z = 4. The complex is a high melting, colorless solid that has a distorted tetrahedral CdS₄ coordination geometry. Thermogravimetric analysis results for the title compound as well as for another potential CdS synthon and two potential CdSe synthons are reported. Graphical Abstract  The synthesis and characterization of the title compound, a new ionic homoleptic cadmium complex, tetrakis[1-methyl-3-(2-propyl)-2(3H)-imidazolethione]cadmium(II) hexafluorophosphate is reported. The results of a single crystal X-ray diffraction analysis reveal a distorted tetrahedral CdS₄ coordination sphere about the cadmium. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Crystal and Molecular Structure of the 1:2 Salt Formed Between 1,2-(4-Pyridyl)Ethane and 2-(4-Hydroxyphenylazo)Benzoic Acid

Abstract  Proton transfer occurred during co-crystallization of 1,2-(4-pyridyl)ethane with 2-(4-hydroxyphenylazo)benzoic acid to yield a salt comprising a 1:2 ratio of 1,2-bis(4-pyridinium)ethane dications and 2-(4-hydroxyphenylazo)benzoate anions. Centrosymmetrically related anions associate by charge-assisted O–H···O hydrogen bonds to form 24-membered {···OC₃N₂C₄OH}₂ synthons. These are connected into a supramolecular polymer via charge-assisted N–H···O hydrogen bonds involving the 1,2-bis(4-pyridinium)ethane dications. The compound crystallizes in the triclinic space group P−1 with a = 8.517(4) ?, b = 9.110(5) ?, c = 10.477(5) ?, α = 96.850(13)°, β = 94.446(12)°, γ = 104.946(10)° and Z = 1 {two anions and a dication}. Index Abstract  Supramolecular chains mediated by charge-assisted O–H···O and N–H···O hydrogen bonding are found in the salt containing a 1:2 ratio of 1,2-bis(4-pyridinium)ethane dications and 2-(4-hydroxyphenylazo)benzoate anions.      

Spectroscopic Studies and Crystal Structure of 1-[(2,5-dioxopyrrolidin-1-yl)(phenyl) methyl] Thiourea

Abstract  A new mannich base 1-[(2,5-dioxopyrrolidin-1-yl)(phenyl)methyl] thiourea formed by the direct condensation of thiourea, succinimide and benzaldehyde has been synthesized. The structure of this mannich base has been elucidated on the basis of micro elemental analysis, IR, ¹H NMR, ¹³C NMR, Mass and UV–Visible Techniques. The crystal structure of the title compound C₁₂ H₁₃ N₃ O₂ S was determined. It crystallizes in the monoclinic system, space group P2₁/c with a = 10.8234 (7) ?, b = 6.0355 (5) ?, c = 19.3692 (14) ?, β = 100.540(3)°, Z = 4 and V = 1243.94 (16) ?³. The structure was solved by the full-matrix least squares on F ² and had a refined R value of 0.0465 for 1,964 observed reflections. The crystal structure is stabilized by strong intramolecular C–H···O, C–H···S interactions and inter molecular N–H···O and S···S interactions. Graphical Abstract  This paper describes the spectroscopic and crystallographic studies of the title compound which is essential in ascertaining the structure of this new compound.      

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.      

The Synthesis and Crystal Structure of New Bis(3-chlorophenyl)-[5-methyl-1-(4-methylphenyl)-1,2,3-triazol-4-yl]-methanol

Abstract  The title compound bis(3-chlorophenyl)-[5-methyl-1-(4-methylphenyl)-1,2,3-triazol-4-yl]-methanol 8 has been synthesized and established by H NMR, IR and MS spectra and X-ray diffraction crystallography. Compound 8, C₂₃H₂₉Cl₂N₃O, Mr = 424.31, crystallizes in the monoclinic space group P2₁/c with unit cell parameters a = 14.5402(6) ?, b = 12.5888(5) ?, c = 11.6510(5) ?, α = 90o, β = 100.183o(2), γ = 90o, V = 2099.05(15) ?³, D_x = 1.343 mg m⁻³ and Z = 4. The final R was 0.0514. The molecular conformation and packing is stabilized by interactions of intermolecular O1–H1···N3′. Index Abstract  The structure of bis(3-chlorophenyl)-[5-methyl-1-(4-methylphenyl)-1,2,3-triazol-4-yl]-methanol by the reaction of compound 4 and Grignard regent is studied.      

Crystal and Molecular Structure of Dichloro(ethylenediamine)gold(III) Nitrate: [Au(NH<Subscript>2</Subscript>CH<Subscript>2</Subscript>CH<Subscript>2</Subscript>NH<Subscript>2</Subscript>)Cl<Subscript>2</Subscript>]NO<Subscript>3</Subscript>

Abstract  The gold(III) atom in [Au(NH₂CH₂CH₂NH₂)Cl₂]NO₃ is chelated by the ethylenediamine (en) ligand and the approximately square planar geometry is completed by two chloride atoms. Weak Au···O and Au···Cl contacts are noted above and below the square plane leading to a tetragonally distorted octahedron for the gold(III) center. Extensive charge-assisted hydrogen bonding of the type N–H···O leads to the formation of a 2-D array and layers are consolidated into a 3-D network via C–H···O and C–H···Cl contacts. The compound crystallizes in the orthorhombic space group Pbca with a = 10.3380(11) ?, b = 8.2105(7) ?, c = 19.625(2) ?, and Z = 8. Index Abstract  Square planar complex cations form additional Au···O and Au···Cl interactions to form a tetragonally distorted octahedron for gold. The ionic components are connected into a 2-D array via charge-assisted N–H···O hydrogen bonding interactions.      

New Toluene Hemi Solvate of the Proton Pump Inhibitor Piperazinium Esomeprazolate

Abstract  The new toluene hemisolvate of the piperazinium salt of esomeprazole, ((S)-5-methoxy-2-[(4-methoxy-3,5-dimethyl-pyridin-2-yl)methylsulfinyl]-3H-benzimidazole, C₁₇H₁₉N₃O₃S) has the composition piperazinium esomeprazolate 0.5 toluene. The unit cell has monoclinic P2₁ symmetry with the cell parameters a = 10.0903(16) ?, b = 16.234(3) ?, c = 15.316(2) ?, β = 92.746(12)°, V = 2,506.0(7) ?³. It contains four piperazinium, four esomeprazolate and two toluene molecules. The crystal structure exhibits intermolecular hydrogens bonds within the layers and Van der Waals contacts between the layers. Additionally, three new crystal phases of solvent-free piperazinium esomeprazolate were found. Index Abstract  The title compound is a toluene hemisolvate of the piperazinium salt of esomeprazole, ((S)-5-methoxy-2-[(4-methoxy-3,5-dimethyl-pyridin-2-yl)methylsulfinyl]-3H-benzimidazole. Single crystal X-ray diffraction analysis reveals that the molecules crystallize in layers. In a layer the molecules are held together by classical hydrogen bonds whereas the layers on the other hand are connected by vdW contacts.      

Crystal Structure of 4,7-Dichloro-1,2,3,5,6,8-hexakis-(4-methoxy-phenylsulfanyl)-acenaphthylene

Abstract  The title compound was prepared from the reaction of perchloroacenaphthylene with an excess of sodium salt of 4-methyloxythiophenol in toluene/ethanol (1:1) solvent and structurally characterized by single-crystal X-ray diffraction. The compound crystallizes in the Monoclinic space group P2(1) with the parameters: a = 10.351(1) ?, b = 20.453(3) ?, c = 12.1837(16) ?, β = 105.584(3)°, V = 2484.5(6) ?³, with Z = 2 formula units. Graphical Abstract   The title compound 4,7-dichloro-1,2,3,5,6,8-hexakis-(4-methoxy-phenylsulfanyl)-acenaphthylene was synthesized from perchloroacenaphthylene C ₁₂ Cl ₈ with an excess of 4-methoxybenzene thiolate in toluene/ethanol (1:1) .     

Synthesis and Structural Comparison for a Series of Cr(II) (iodo) NacNac Complexes

Abstract  A series of complexes of the form [bis(2,6-diisopropylphenyl)pentane-2,4-ketiminato](iodo)(solvent) chromium were synthesized and structurally characterized (solvent = tetrahydrofuran, acetonitrile, α-picoline). The tetrahydrofuran adduct crystallized in the P2₁/n space group with the crystal cell parameters a = 17.628(6) ?, b = 10.218(3) ?, c = 20.646(7) ?, β = 109.209(4)°, V = 3512(2) ?³ and Z = 4. The acetonitrile adduct crystallized in the P2₁/c space group with the crystal cell parameters a = 16.104(7) ?, b = 11.965(5) ?, c = 18.201(8) ?, β = 116.091(6)°, V = 3150(2) ?³ and Z = 4. The α-picoline adduct crystallized in the C2/c space group with the crystal cell parameters a = 39.982(9) ?, b = 11.637(2) ?, c = 16.560(4) ?, β = 108.085(4)°, V = 7325(3) ?³ and Z = 8. For each compound, the coordination around each chromium center is square planar with varying degrees of distortion. Graphical Abstract  A series of Cr(II) complexes of the form LCrI(S) (where L = nacnac = β-diketiminate; S = solvent) were synthesized and structurally characterized.      

Crystal Structure of 9α,11-Epoxy-7α-(methoxycarbonyl)-3-oxo-17α-pregn-4-ene-21,17-carbolactone

Abstract  The title compound (common name eplerenone), C₂₄H₃₀O₆, is an aldosterone receptor antagonist. From the isopropyl acetate solution the compound crystallizes in monoclinic space group P 21 with a = 8.811(1) ?, b = 11.250(1) ?, c = 11.079(1) ?, β = 93.822(12)°, Z = 2. The molecule contains three six membered rings, two five membered rings and one three membered ring. Both five membered rings display envelope conformation, whereas three six membered rings show different conformation: chair, half-chair and envelope. In the crystal the eplerenone molecules link to one another via intermolecular weak C–H···O hydrogen bonding to form the smaller cavity of 12.0(1) ?³ between eplerenone molecules, no solvent molecule filled in this cavity. Index Abstract  In the title molecule three six-membered rings show different conformation. Weak C–H···O hydrogen bonding links adjacent molecules to form the small cavity 12.0(1) ?³, no solvent molecule filled in the cavity.      

Synthesis of (2,4-Diamino-5-(3′,4′,5′-trimethoxybenzyl) Pyrimidine) Copper (II) Complex at 20–25 °C and its Structural Characterization

Abstract  The title copper (II) complex with Trimethoprim was prepared at 20–25 °C and its crystal structure was determined by single crystal X-ray diffraction. Compound (C₃₆H₅₀Cu₃N₈O₁₆) is triclinic, space group P-1 with a = 6.4642(5) ?, b = 12.5495(9) ?, c = 13.4911(10) ?, α = 77.518(1)°, β = 85.326(1)°, γ = 84.413(2)°, Z = 1. In this compound, three copper atoms are bonded to each other, two terminal coppers are bonded to three oxygen atoms and N₁ of pyrimidine ring of Trimethoprim and central copper is bonded to four oxygen atoms. The amino nitrogen atoms are not involved in the coordination to the metal. Graphical Abstract  To enhance the activity of trimethoprim, its derivative was prepared and there bacterial activity against several bacteria was analyzed.      

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.      

Synthesis and Structure of [Fe<Subscript>3</Subscript>O(O<Subscript>2</Subscript>CCH<Subscript>2</Subscript>OMe)<Subscript>6</Subscript>(H<Subscript>2</Subscript>O)<Subscript>3</Subscript>][FeCl<Subscript>4</Subscript>]

Abstract  The structure of [Fe₃O(O₂CCH₂OMe)₆(H₂O)₃][FeCl₄] · 2.5H₂O has been determined. The three iron atoms and the μ₃-oxo are coplanar. Each carboxylic ligand is bidentate and links two iron atoms in the cluster. The clusters are linked by intra-trimer hydrogen bonding to form a zigzag motif that forms sheets via hydrogen bonding involving disordered waters of hydration. The [FeCl₄]⁻ anion is intercalated between the hydrogen-bonded sheets. Crystal data: space group P2₁/n, a = 10.276(2), b = 22.793(5), c = 17.091(3) ?, β = 96.66(3)°, V = 3976(1) ?³, Z = 4, R = 0.0837, wR ₂ = 0.1836. Graphical Abstract  The structure of [Fe₃O(O₂CCH₂OMe)₆(H₂O)₃][FeCl₄] · 2.5H₂O has been determined in which the clusters are linked by intra-trimer hydrogen bonding to form a zigzag motif that forms sheets via hydrogen bonding involving disordered waters of hydration.      

An X-Ray Crystallographic Study of the Novel Aminal bis-(<Emphasis Type="Italic">p</Emphasis>-Ethoxycarbonylphenylamino-)methane

Abstract  The crystal structure of bis-(p-Ethoxycarbonylphenylamino-)methane (1) has been determined by single crystal X-ray diffraction analysis. The bis-aminal (1) molecule is V-shaped and situated on a twofold axis passing through C1 with the phenyl rings forming a dihedral angle of 70.2(1)°. The carboxylate and phenyl groups are coplanar. The crystal structure of 1 is compared with the structure of the closely related aminals, 2–5. Crystal data: 1 C₁₉H₂₂N₂O₄, tetragonal, space group I4 ₁ cd (N.110), a = 20.4760(7) Ǻ, b = 20.4760(7) Ǻ, c = 8.2984(3) ?, and V = 3477.7(2) ?³, for Ζ = 8. Index Abstract  The crystal structure of bis-(p-ethoxycarbonylphenylamino-)methane (1) has been determined by single crystal X-ray diffraction analysis.