Molecular Structures Of 2a Research Articles

From ferrocenyl selenoesters to diferrocenyl methanols

The reaction of FcSeSiMe3 (Fc = Fe(η5-C5H5)(η5-C5H4)) (1) with equimolar amounts of the acid chlorides Cl(O)C-2-cC4H3X (2a, X = O; 2b, X = NMe) gave the ferrocenyl selenoesters FcSe(C(O)-2-cC4H3X) (3a, X = O; 3b, X = NMe). Upon exposure to silica gel compounds both 3a and 3b underwent an intermolecular conversion followed by transesterification with the silica surface to afford diferrocenyl methanols Fc2C(OH)(2-cC4H3X) (4a, X = O; 4b, X = NMe). Compounds 3a, 3b, 4a and 4b have been characterized by elemental analysis, IR and NMR (1H, 13C{1H}, 77Se{1H}) spectroscopy and ESI-TOF mass spectrometry (4a and 4b). The molecular structures of 3a, 4a and 4b in the solid state were determined by single crystal X-ray diffraction studies. The electrochemical studies exhibit for 3a and 3b reversible one-electron Fc/Fc+ redox processes. During the electrochemical investigations of 4a and 4b two well-separated one-electron redox events could be determined (4a, ΔE0’ = 330 mV; 4b, 367 mV). UV-Vis/NIR spectroelectrochemical studies on 4a and 4b reveal a weak electronic coupling between the iron centers in the corresponding mixed-valent species of [4a]+ and [4b]+ according to Robin and Day classification.

Synthesis of three new thiophene condensed pyrene derivatives, crystal structure and evaluation of their photophysical properties

Three new thiophene condensed fluorescent pyrene derivatives have been synthesized by a two-step process, via. Wittig reaction followed by iodine promoted photocyclization. These molecules have been characterized by 1H NMR and EI-MS. Further, the molecular structures of 4a, 4b and 4c has been confirmed by single crystal X-ray diffraction analysis. The protons located in the fjord and cove-regions of molecules 4b and 4c showed downfield shifts of the protons. Molecule 4a crystallized under monoclinic system with space group P21/c, molecule 4b crystallized under monoclinic system with space group C2/c and the molecule 4c crystalized under triclinic system with space group P-1. Molecules 4a, 4b and 4c showed strong absorption maxima wavelengths at 305, 358 and 330 nm, respectively. The molar extinctinction coefficients (ε) of the compounds 4a, 4b and 4c indicated molecule 4c has better ability to absorb UV light, molecule 4b has better fluorescence intensity than molecule 4a and 4c.

Synthetic, spectroscopic and structural behavior of unsaturated functionalized N-heterocyclic carbene complexes of group 11

A series of unsaturated functionalized silver(I) N-heterocyclic carbenes [{(κC-C7N2H10)AgCl}2] (1a), [{(κC-C8N2H12)2}2Ag][Ag2Cl4] (1b), [{(κC-C9N2H14)2Ag}2][Ag2Cl4] (1c), and [{(κC-C12N2H14)2Ag}2][Ag2Cl4] (1d) have been synthesized and used as transmetalation agents to form the corresponding Au(I) and Cu(I) complexes. The reactions of 1a-d with [Au(SMe2)Cl] or CuI produced the mixed-metal biscarbene compounds [(κC-C7N2H10)2M][AgCl2] (M=Au 2a; Cu 3a), [{(κC-C8N2H12)2}2M][Ag2Cl4] (M=Au 2b; Cu 3b), [{(κC-C9N2H14)2M}2][Ag2Cl4] (M=Au 2c; Cu 3c), and [{(κC-C12N2H14)2}2M][Ag2Cl4] (M=Au 2d; Cu 3d). The carbene complexes were fully characterized by IR, NMR and mass spectrometry, and the molecular structures of 1a, 1b, 2b and the imidazolium salt [PMIM][PF6] (L2′) were determined by single crystal X-ray diffraction studies. Compounds L4, 1d and 2d were used as monomeric units to carry out free-radical polymerization (FRP) reactions using AIBN as initiator.

Synthesis of Two Novels-Shaped Dibenzo[c,l] Chrysene Derivatives, Crystal Structure, and the Evaluation of their Photophysical Properties

Two s-shaped polyaromatic dibenzo[c,l]chrysene derivatives have been synthesized by a two-step process, via. The Wittig reaction, followed by iodine, promoted photocyclization. These molecules have been characterized by 1H NMR, FAB-MS, and elemental analysis. Further, the molecular structures of 4a and 4b have been confirmed by single crystal X-ray diffraction analysis. The protons located in the cove-regions of molecules 4a and 4b showed downfield shifts of the protons. Molecule 4a crystallized under the monoclinic system with space group C2/c, and the molecule 4b crystallized under the monoclinic system with space group P21/n. Molecules 4a and 4b showed strong absorption maxima wavelengths at 310 nm and 324 nm, respectively. The molar extinctinction coefficients (ε) of the compounds 4a and 4b indicated that molecule 4b has a better ability to absorb UV light than molecule 4a. The emission spectra of the molecules 4a and 4b displayed peaks in the region 429–456 nm. The shape of the UV-Visible and Fluorescence spectra of the molecules 4a and 4b look almost identical. However, molecule 4b exhibited better fluorescence intensity than molecule 4a. This may be due to the difference in the substituents of molecules 4a and 4b.

Straightforward synthesis of ferrocenyl allylic thioethers

The new ferrocenyl allylic thioethers FcCH=CHCH2SR (2a–e) and FcCH(SR)CH=CH2 (3a–e) (R=Ph, a; 2-naphthyl, b; 3,5-C6H3Me2, c; iPr, d; tBu, e) were synthesized in good yields from ((2-ferrocenylvinyl)methyl)trimethylammonium iodide, [1]+I− and the corresponding thiol RSH. With sufficiently strong bases to fully deprotonate the thiol, good to excellent regioselectivities (88–99%) in favor of the linear isomer 2 were obtained. The molecular structures of 2a and 2b were obtained by X-ray diffraction on monocrystals. A mechanistic proposal based on experimental data and supported by calculations is also presented, underlying the role of the base in the reaction regioselectivity.

Insights into Molecular Beryllium–Silicon Bonds

We present the synthesis of two silyl beryllium halides HypSiBeX∙(thf) (HypSi = Si(SiMe3)3, X = Cl 2a, I 4a) and the molecular structure of 2a as determined by single crystal X-ray diffraction. Compounds 2a and 4a were characterized via multi-nuclear NMR spectroscopy (1H, 9Be, 13C, 29Si), and the bonding situation was further investigated using quantum chemical calculations (with the addition of further halides X = F 1b, Cl 2b, Br 3b, I 4b). The nature of the beryllium silicon bond in the context of these compounds is highlighted and discussed.

Syntheses, characterization and catalytic activities of half-sandwich ruthenium complexes with naphthalene-based Schiff base ligands

Four ruthenium(II) p-cymene complexes with naphthalene-based Schiff base ligands [Ru(p-cymene)LCl] (2a–2d) have been synthesized and characterized. The half-sandwich ruthenium complexes were characterized by 1H and 13C NMR spectra, elemental analyses, and infrared spectrometry. The molecular structures of 2a, 2b, and 2c were confirmed by single-crystal X-ray diffraction. Furthermore, these half-sandwich ruthenium complexes are highly active catalysts for the hydrogenation of nitroarenes to anilines using NaBH4 as the reducing agent in ethanol at room temperature.

Synthesis of new spirooxindole-pyrrolothiazole derivatives: Anti-cancer activity and molecular docking

The 1,3-dipolar cycloadditions of an azomethine ylide generated from isatin and thiazolidinecarboxylic acid to a series of 2,6-bis[(E)-arylmethylidene]cyclohexanones afforded new di-spiro heterocycles incorporating pyrrolidine and oxindole rings in quantitative yields and chemo-, regio-, and stereoselectively. The newly synthesized compounds were characterized using spectroscopic techniques. Furthermore, the molecular structures of 4a, 4e, and 4n were confirmed by X-ray crystallography. These newly synthesized compounds were screened for their in vitro activity against breast cancer cell line MCF-7 and K562-leukemia. 4k was found to be the most potent compound of this series in targeting MCF-7 breast cancer cells and K562-leukemia, with IC50 values of 15.32±0.02 and 14.74±0.7μM, respectively. The molecular studies of the synthesized compounds were investigated.

Syntheses, Crystal Structure and Photoluminescence Properties of Piperidinium Tetrakis (1,3-Diphenyl-1,3-Propanedionato) Europate(III) Complex and Its Two Different Crystals

Treatment of 1,3-diphenyl-1,3-propanedione 1a with europium (III) chloride in the presence of piperidine results in the halide ligands exchange giving newly piperidinium tetrakis (1,3-diphenyl-1,3-propanedionato)europate(III) complex 2a. The complex was characterized by 1H-NMR, positive FAB-mass, and Elemental Analysis. The exact molecular structure of 2a was determined by single crystal X-ray diffraction with the monoclinic space group Cc (centrosymmetric, No.13). The large cavity sizes of the complex 2a facilitated the inclusion of water and benzene solvate molecules. The other two different crystals 2b, 2c having two water molecules and one benzene moleculewere obtained by the crystallization in different solvents and the exact molecular structures were determined by single crystal X-ray diffraction analysis with space groups P21/n (centrosymmetric, No.14), and P21/n (centrosymmetric, No.14), respectively. The eight coordinate structures of the complexes in the three crystals were slightly different due to the crystal packing and the existence of the solvent molecule(s). The photoluminescence studies indicated that four β-diketone ligands acted as strong antenna ligands and transferred the absorbed energy to europium (III) ion, consequently red luminescence was observed. These strong emissions wereattributed to the 5D0 → 7F2 transition of Europium (III) ions under UV excitation. The photoluminescence spectrum of the three crystals was almost same in solid as well as in solution.

Oligogermanes Containing Only Electron-Withdrawing Substituents: Synthesis and Properties

A series of germanes Ar3GeX, containing electron-withdrawing substituents [Ar = p-FC6H4, 1a–d, 1a (X = Cl), 1b (X = Br), 1c (X = H), 1d (X = NMe2); p-F3CC6H4, 2a–d, 2a (X = Cl), 2b (X = Br), 2c (X = H), 2d (X = NMe2)], was synthesized and used to prepare symmetrical digermanes Ar3Ge–GeAr3, (p-FC6H4)3GeGe(C6H4F-p)3 (3), and (p-F3CC6H4)3GeGe(C6H4CF3-p)3 (4) and trigermane [(p-F3CC6H4)3Ge]2Ge(C6F5)2 (5) by hydrogermolysis reaction. The properties of all compounds were investigated by multinuclear NMR and for oligogermanes by UV/vis and fluorescence spectroscopy, as well as by electrochemical methods. In addition, the molecular structures of 1a, 1b, 2b, 2c, and 3–5 were studied by X-ray diffraction analysis. Compound 5 showed a significantly shifted UV/visible absorption to the red field in comparison with previously described derivatives.

Photochemical Alkyne Insertions into the Iron–Thiocarbonyl Bond of [Fe2(CS)(CO)3(Cp)2

Internal alkynes (RC≡CR) react with [Fe2(CS)(CO)3(Cp)2] (1), under UV radiation, to give the complexes [Fe2{μ-η1:η3-C(R)═C(R)C═S}(μ-CO)(CO)(Cp)2] [R = Et, 2a; R = Ph, 2b; R = CO2Me, 2c], as a result of CO displacement and alkyne insertion into the metal–CS bond of 1. In addition, the reaction of 1 with EtC≡CEt affords the metallacycle species [Fe2{μ-η2:η2-C(S)C(Et)═C(Et)C(O)}(CO)2(Cp)2] (3) as secondary product. The molecular structures of 2a and 3 have been elucidated by X-ray diffraction studies. Compound 1 reacts with HC≡CCO2Me, affording the complex [Fe2{μ-η1:η3-C(H)═C(CO2Me)C═S}(μ-CO)(CO)(Cp)2] (2d) in modest yield. Complexes 2a,b undergo selective methylation at the sulfur atom, generating the cationic complexes [Fe2{μ-η1:η3-C(R)═C(R)═C(SMe)}(CO)(μ-CO)(Cp)2][CF3SO3] [R = Et, 4a; R = Ph, 4b]. The X-ray structure of 4a has also been determined. Finally, 4b undergoes nucleophilic addition of hydride and cyanide (from NaBH4 and NBun4CN, respectively) to form the vinylalkylidene complexes [Fe2{μ-η1:η3-C(...

Reactivity of [WCl6] with Ethers: A Joint Computational, Spectroscopic and Crystallographic Study

The reactions of [WCl6] with a series of ethers have been performed in chlorinated solvent and elucidated by means of analytical, spectroscopic and DFT methods. The addition of tetrahydropyran (thp) or 1,4‐dioxane to [WCl6] resulted in the reversible formation of the adducts WCl6···L [L = thp (1a), 1,4‐dioxane (1b)], detected in solution by NMR spectroscopy. The reaction of [WCl6] with thp in a molar ratio of 1:2 in chloroform at reflux afforded [WOCl4(thp)] (2a), which was isolated in 51 % yield. [WOCl4(OMe2)] (2b) and [WOCl3(OMe2)2] (3a) were isolated in yields of 53 and 18 %, respectively, from the reaction of [WCl6] with an excess of dimethyl ether. [WOCl3(OEt2)2] (3b) was the only identified metal compound produced from the reaction of [WCl6] and OEt2 (1:2 molar ratio). According to NMR studies, the oxide ligand in 2a,b and 3a,b was generated by double C–O bond cleavage involving one equivalent of organic reactant. The 1:1 reaction of [WCl6] with 1,2‐diethoxyethane led to [WCl5(κ1‐OCH2CH2OEt)] (4) and a minor amount of [WCl4(κ2‐EtOCH2CH2OEt)] (5). The aryl oxide compound [WCl5(OPh)] (6) was prepared in 62 % yield from the reaction of [WCl6] and anisole by selective Csp3–O bond activation. The prolonged heating of a mixture of [WCl6] and diphenyl ether in 1,2‐dichloroethane led to the isolation of the WV complex [WCl5(OPh2)] (7). The molecular structures of 2a and 3a were ascertained by X‐ray diffraction.

Synthesis of Quinoline-Based NNN-Pincer Nickel(II) Complexes: A Robust and Improved Catalyst System for C–H Bond Alkylation of Azoles with Alkyl Halides

The quinoline-based pincer nickel(II) complexes κN,κN,κN-{R2N-C6H4-(μ-N)-C9H6N}NiX ((R2NNNQ)NiCl: R = Me, 2a; R = Et, 2b) were synthesized by the reaction of the ligand precursors (R2NNNQ)H (R = Me, 1a; R = Et, 1b) with (DME)NiCl2 in the presence of Et3N. Similarly, the pincer nickel(II) derivatives (R2NNNQ)NiX (R = Me, X = Br, 3a; R = Et, X = Br, 3b; R = Me, X = OAc, 4a) were obtained by treatment of the ligands (R2NNNQ)H with the nickel precursor (THF)2NiBr2 or Ni(OAc)2. All of these complexes were characterized by 1H and 13C NMR spectroscopy as well as by elemental analysis. Further, the molecular structures of 2a and 3a,b were elucidated by X-ray crystallography. Complex 2a is found to be an efficient catalyst for the direct C–H bond alkylation of substituted benzothiazoles and oxazoles with various unactivated alkyl halides containing β-hydrogens under mild reaction conditions. The catalyst 2a is very robust and was recycled and reused five times for the alkylation reaction without a decrease in its ...

(Ferrocenylthienyl)phosphines: Synthesis, electrochemistry and their use in Suzuki-Miyaura C,C coupling

(Ferrocenylthienyl)phosphines of type 2-PR2-5-Fc-cC4H2S (R = Ph (3a), tBu (3b)) and 2-PR2-3,4-Fc2-cC4HS (R = Ph (4a), tBu (4b); Fc = Fe(η5-C5H4)(η5-C5H5)) and their selenium derivatives were synthesized by consecutive synthetic methodologies. The molecular structure of 3a and 4a,b in the solid state show inter- and intramolecular (T-shaped) π–π interactions for 3a and 4a, resulting in dimeric and 1D polymeric structures.Phosphines 3a,b and 4a,b were applied in the Pd-catalyzed Suzuki-Miyaura C,C cross coupling reaction of aryl halides and boronic acids yielding the respective biaryls. Compound 3b shows a higher activity in C,C cross coupling reactions as compared to 3a and previously published thiophene-based phosphines and aminophosphines. Moreover sterically hindered and deactivated aryl bromides could be coupled at Pd loadings as low as 0.05 mol-% and at temperatures between 25 °C and 50 °C. However, the application of diferrocenylthienylphosphines 4a,b in Suzuki-Miyaura reactions resulted in decreased yields of the corresponding biaryls.In the context of electrochemical investigations on these compounds, a strong dependency of the individual electrode reactions on the phosphorus substituents were found. During UV–Vis/NIR spectroelectrochemical studies, only a very limited iron-iron electronic interaction in 4a-Se+ could be detected. Thus, 4a-Se+ corresponds to a very weak coupled class II system according to the classification of Robin and Day.

RuII(η6‐p‐cymene) Complexes of Bioactive 1,2‐Benzothiazines: Protein Binding vs. Antitumor Activity

Abstract1,2‐Benzothiazine‐3‐carboxamide 1,1‐dioxide derivatives such as meloxicam are known to display numerous pharmacological activities. We prepared a series of 4‐hydroxy‐2‐alkyl‐2H‐benzo[e][1,2]thiazine‐3‐carboxamide 1,1‐dioxide ligands 1a–f and their Ru(η6‐p‐cymene) complexes 2a–f, inspired by synergistic effects observed with other bioactive ligands coordinated to metal centres. The molecular structures of 1a, 2a, and 2b were determined by X‐ray diffraction analyses. The stability of the metal complexes was characterized in DMSO and DMSO/H2O on the basis of 1H NMR spectroscopy and their protein binding capabilities were studied using mass spectrometry. In vitro cytotoxicities of the Ru complexes were determined against human colorectal carcinoma (HCT116), non‐small cell lung carcinoma (NCI‐H460) and cervical carcinoma (SiHa) cell lines. The low levels of biological activity observed for these Ru complexes were put into context by considering their chemical reactivity with proteins. The binding of proteins resulted in cleavage of the benzothiazine backbone when the complex was present in concentrations equimolar with respect to protein.

Binuclear aluminum complexes with amine–imine type ligands derived from 1,3-benzenedialdehyde: synthesis, structures and their catalytic properties in ring-opening polymerization

Reaction of 1,3-bis(imino)benzenes with a stoichiometric amount of LiAlH4 in THF yields iminoaminobenzenes L1 and L2. Further reaction of iminoaminobenzenes L1 and L2 with an equivalent of AlR3 in toluene affords macrocyclic binuclear aluminum complexes 1a, 1b, and 2a. These macrocyclic aluminum complexes were characterized by 1H NMR, 13C NMR, and IR spectroscopy. The molecular structures of 1a, 1b, and 2a were further confirmed by X-ray crystallography. X-ray diffraction analysis revealed that 1a, 1b, and 2a adopted a distorted tetrahedral geometry around aluminum. These complexes have efficient activities toward ring-opening polymerization of ε-caprolactone in the presence of benzyl alcohol.

Synthesis and solid state structures of Chalcogenide compounds of Imidazolin-2-ylidene-1,1-Diphenyl-phosphinamine

We report the synthesis and solid state structures of 1,3-di-aryl-imidazolin-2-ylidine-1,1-diphenylphosphinamine [(aryl = mesityl (1a) and aryl = 2,6-diisopripyl (1b)] and their chalcogenide compounds 1, 3-di-aryl-imidazolin-2-ylidine- P,P-diphenylphosphinicamide (2a,b), 1,3-di-aryl-imidazolin-2-ylidine-P,P-diphenyl-phosphinothioicamide (3a,b) and 1,3-diaryl-imidazolin-2-ylidine- P,P-diphenyl-phosphinoselenoic-amide (4a,b). The compounds 1a,b were prepared in good yield by the reaction of 1,3-di-aryl-imidazolin-2-imine and chlorodiphenylphosphine in the presence of triethylamine in toluene. The reactions of 1a,b with elemental sulphur and selenium afforded the corresponding chalcogenide compounds 3a,b and 4a,b respectively. The corresponding oxo- derivative (2a,b) was obtained by reacting compound 1a,b with 30% aqueous hydrogen peroxide in THF. The molecular structures of 1a, 2a, 3a and 4a,b have been established by single crystal X-ray diffraction analyses. The molecular structures reveal that even C1–N1–P1 angle (124.62 ∘) in compound 1a is less obtuse compared to the corresponding C1–N1–Si1 angles (157.8 ∘) observed in related N-silylated 2-iminoimidazolines and trimethylsilyl iminophosphoranes. C1–N1–P1 angles are further widened in compounds 2a, 3a, and 4a,b due to the attachment of chalcogen atoms onto phosphorus atom.

Improved synthesis of perfluoroalkyl substituted 1,3,4-oxadiazoles as precursors for corresponding 1,2,4-triazoles

An improved and more efficient synthesis of 2,5-bis(trifluoromethyl)-1,3,4-oxadiazole (2a), 2,5-bis(perfluoroethyl)-1,3,4-oxadiazole (2b), 2-(perfluoroethyl)-5-(trifluoromethyl)-1,3,4-oxadiazole (2d) and 2-(perfluoroheptyl)-5-(trifluoromethyl)-1,3,4-oxadiazole (2e), via ring-opening reactions of the corresponding sodium 5perfluoroalkyltetrazolates (10a-b) is described. Furthermore the named perfluoroalkyl-1,3,4-oxadiazoles (2a-b & 2d) were converted into the corresponding 3,5-bis(trifluoromethyl)-1,2,4-triazole (1a), 3,5-bis(perfluoroethyl)-1,2,4-triazole (1b) and 5-(perfluoroethyl)-3-(trifluoromethyl)-1,2,4-triazole (1d), by in situ produced ammonia (urea and potassium hydroxide). All products were characterized using multinuclear (1H, 13C, 19F) NMR spectroscopy and differential scanning calorimetry to determine the structure and thermodynamic characteristics. Additionally, the molecular structure of 1a was determined by single crystal X-ray diffraction.

Synthesis, Structures, and Norbornene Polymerization Behavior of Palladium Complexes Bearing Tridentate o-Aryloxide-N-heterocyclic Carbene Ligands

A series of new pincer-type tridentate o-aryloxide-N-heterocyclic carbene ligands 2a–d were synthesized. Treatment of the proligands with Ag2O and (COD)PdCl2 afforded the desired o-aryloxide-NHC tridentate palladium complexes 3a–d in high yields (NHC = N-heterocyclic carbene). In comparison with the above tridentate complexes, bidentate bis(aryloxide-NHC) palladium complex 3e was also synthesized. All of these complexes were fully characterized by 1H and 13C NMR spectroscopy, high-resolution mass spectrometry, and elemental analysis. The molecular structures of 3a,b,d,e were determined by single-crystal X-ray diffraction analysis. On activation with either methylaluminoxane (MAO) or diethylaluminum chloride (Et2AlCl), all palladium complexes exhibited excellent activities of up to 5.99 × 107 g of PNB (mol of Pd)−1 h–1 toward norbornene addition polymerization, and the monomer conversion is up to 99.9%. Notably, the tridentate palladium complexes show better activities than the corresponding bidentate bis(...

Half-sandwich cycloruthenated complexes from aryloxazolines: synthesis, structures, and catalytic activities.

Seven half-sandwich cycloruthenated complexes [Ru(p-cymene)LCl] (2a-2g) (L = 2-phenyl-2-oxazoline (2a), 2-p-tolyl-4,5-dihydrooxazole (2b), 4,4-dimethyl-2-phenyl-2-oxazoline (2c), 2-(4-chlorophenyl)-4,5-dihydrooxazole (2d), 2-(4-bromophenyl)-4,5-dihydrooxazole (2e), 2-(4-fluorophenyl)-4,5-dihydrooxazole (2f) and 2-(4-nitrophenyl)-4,5-dihydrooxazole (2g)) were synthesized and characterized. All half-sandwich cycloruthenated complexes were fully characterized by (1)H and (13)C NMR spectra, elemental analyses and infrared spectroscopy. The molecular structures of 2a, 2d and 2e were confirmed by single-crystal X-ray diffraction methods. These half-sandwich cycloruthenated complexes were employed in nitroarene reduction using sodium borohydride (NaBH4) as a reducing agent in ethanol at room temperature. The catalytic results indicate that half-sandwich cycloruthenated complexes show promising catalytic activity in nitroarene reduction with a broad substrate and varied functional group compatibility.