Synthesis,crystal structure and properties of two terbium complexes with 2,2′-bipyridine

Two new complexes {[Tb(2-IBA)₃ · 2,2′-bipy]₂ · C₂H₅OH} (1) and [Tb(2-ClBA)₃ · 2,2′-bipy]₂ (2) (2-IBA = 2-iodobenzoate; 2-ClBA = 2-chlorobenzoate; 2,2′-bipy = 2,2′-bipyridine) were prepared and their crystal structures determined by X-ray diffraction. Complex 1 is composed of two types of binuclear molecules, [Tb(2-IBA)₃ · 2,2′-bipy]₂ (a) and [Tb(2-IBA)₃ · 2,2′-bipy]₂ (b), and an uncoordinated ethanol molecule. In molecule (a), two Tb³⁺ ions are linked by four 2-IBA groups, all bidentate-bridging. In molecule (b), two Tb³⁺ ions are held together by four 2-IBA groups in two coordination modes, bidentate-bridging and chelating-bridging. In the two molecules, each Tb³⁺ ion is further bonded to one chelating 2-IBA group and one chelating 2,2′-bipy molecule, resulting in coordination numbers of eight for (a) and nine for (b). The structural characteristics of 2 are similar to that of molecule (b) in 1. The two complexes, 1 and 2, both emit strong green fluorescence under ultraviolet light with the ⁵D₄ → ⁷F _j (j = 6–3) emission of Tb³⁺ ion observed.     

Synthesis and properties of 2,2′-dipyridyl and 4,4′-dipyridyl complexes with thulium salts

Summary New complexes of 2,2-dipyridyl and 4,4-dipyridyl with thulium salts TmX ₃ (whereX=Cl^–, Br^–, NO ₃ ^– , NCS^–, and ClO ₄ ^– ) have been prepared and their solubilities in water at 21 °C were determined. The IR spectra of these compounds are discussed. The conditions of thermal decomposition of the complexes were also studied.

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Synthese und Eigenschaften von 2,2-Dipyridyl- und 4,4-Dipyridylkomplexen mit Thuliumsalzen

Zusammenfassung Es wurden neue 2,2-Dipyridyl- und 4,4-Dipyridyl-Komplexen mit Thuliumsalzen TmX ₃ (X=Cl^–, Br^– No ₃ ^– , NCS^–, ClO ₄ ^– ) dargestellt und ihre Wasserlöslihkeit bei 21 °C bestimmt. Die IR-Spektren werden diskutiert. Das thermische Verhalten der erhaltenen Komplexe wurde untersucht.

     

Synthesis,structure, and magnetic properties of lanthanide ferrocenoylacetonates with nitrate and 2,2′-bipyridine ligands

Ferrocenoylacetonate complexes of several lanthanides, [Ln(fca)₂(NO₃)(bpy)]·nMeC₆H₅ (Ln = Sm (1), Dy (3), Er (4), Yb (5), n = 1; Eu (2), n = 0.5; fca = FcC(O)CHC(O)Me; bpy = 2,2′-bipyridine), were synthesized and characterized by X-ray single-crystal analysis. Complexes 1, 4, and 5 are isostructural; 2 has a similar molecular structure with cis-disposition of fca ligands. The molecular structure of 3 is different, with trans-disposition of the fca ligands. Crystal lattices of the complexes are stabilized by π-stacking interactions. The Ln³⁺ ions in the complexes are eight-coordinate. According to mass spectroscopic data, the complexes are unstable in the gas phase. Magnetic properties of 2 and 4 were studied in a DC field; for 4, AC studies were also carried out. The values of spin-orbital parameters obtained using two estimation methods for 2 are in satisfactory agreement. Slow relaxation of the magnetization was found for the Er complex.     

Spectroscopic and electrochemical properties of cyclopalladated complexes of 2,3-diphenylquinoxaline and 2,2′,3,3′-tetraphenyl-6,6′-biquinoline

Comparative study of cyclopalladated ethylenediamine complexes of 2,3-diphenylquinoxaline (Hdphqx) [Pd(dphqx)En]ClO₄ and 2,2′,3,3′-tetraphenylbiquinoline (H₂tphbq) [(PdEn)₂(μ-tphbq)](ClO₄)₂, and the free heterocyclic ligands was performed by means of ¹H NMR spectroscopy, electronic absorption and emission spectroscopy, and cyclic voltammetry. It was shown that cyclopalladation gives rise to a long-wave absorption band in the visible spectrum, a batochromic shift of the vibrationally structured phosphorescence band, and an anodic shift of the ligand-centered reduction potential of the complexes com-pared to free ligands.     

Synthesis and charge transfer interactions of cyclobis(4,4′-azopyridinium-p-phenylene)

A new tetracationic cyclophane, cyclobis(4,4′-azopyridinium-p-phenylene) (2.4PF₆), was synthesized via template-directed synthesis and characterized by MS and NMR spectroscopy. For the preparation of π-electron-deficient 2.4PF₆, the use of π-electron-rich templates such as 1,4-bis[2-(2-hydroxyethoxy)ethoxy]-benzene (4) and 1,5-bis[2-(2-hydroxyethoxy)ethoxy]naphthalene (5) enhanced the cyclophane formation in 17 and 19% yields, respectively. ¹H NMR spectra of the reaction mixture revealed that the cyclophane precursor 1.2PF₆ formed supramolecular assembling complexes with hydroquinone derivatives 4 and 5 before the ring formation. The intermolecular charge transfer interaction and the stability constants (K_a) of complexes generated between the electron-acceptor 2.4PF₆ and electron-donors 1,4-dimethoxybenzene 3, 4, and 5 were evaluated using UV-vis. spectroscopy and spectroscopic titration. The absorption bands attributable to CT interactions were centred at 580 nm for 3, 635 nm for 4, and 646 nm for 5, with stability constants of 17 ± 2, 2100 ± 200, and 2400 ± 300, respectively.     

Synthesis,characterization and magnetic properties of coordination polymers of manganese with 1,1′-biphenyl-2,2′-dicarboxylic acid ligands

Three new coordination polymers have been synthesized from 1,1′-biphenyl-2,2′-dicarboxylic acid (2,2-dpa), nitrogen-containing coligands and Mn salts under hydrothermal conditions. The X-ray crystal structures of all three complexes are presented. With the change of nitrogen-containing ligand, the structural features of the complexes also change. The complex prepared without a nitrogen coligand exhibits a one-dimensional covalent chain-like structure, composed of the rare pentanuclear Mn building unit. The complex with 4,4′-bipyridine as a secondary ligand shows a two-dimensional layer structure. With the chelating ligand 1,10-phenanthroline, a discrete molecular complex is synthesized. The magnetic properties of the complex with 4,4′-bipyridine in the temperature range 1.99–300 K are reported.     

Complexes of palladium,platinum and rhodium with 2,2′-biquinoline and 2-(2′-pyridyl)quinoline

Summary The reactions of 2,2-biquinoline(biq) with M(PhCN)₂X₂ (M=Pd; X=Cl or Br; M=Pt, X=Cl, Br or I), K₂PtCl₄ and RhCl₃·3H₂O and of 2-(2-pyridyl)quinoline (pq) with K₂PtCl₄ and RhCl₃·3H₂O have been investigated. The isolated complexescis-[Pd(biq)X₂] (X=Cl or Br),cis-[Pt(biq)Cl₂],cis-[Pt(biq)Cl₂]·H₂O,trans-[Pt(biq)₂Br₂]·5H₂O, [Pt₃(biq)₂I₆],mer-[Rh(biq)Cl₃-(H₂O)] andmer-[Rh(pq)Cl₃(H₂O)] have been characterized by elemental analyses, conductivity measurements, i.r., electronic, and¹H n.m.r. spectra. The reaction of pq with K₂PtCl₄ in 1M H₂SO₄ gave the salt 2-(2-pyridyl) quinolinium tetrachloroplatinate(II) pentahydrate, (pqH)₂[PtCl₄]·5H₂O; when the reaction was carried out in aqueous acetone,cis-[Pt(pq)Cl₂] was obtained. A new method for the synthesis ofcis-[Rh(biq)₂X₂]X (X=Cl or Br) is described; both compounds have been further characterized by¹H n.m.r.     

Synthesis,characterization, and crystal structure determination of Cu(II) coordination compounds with 2,2′-dimethyl-4,4′-bithiazole

[{CuCl(dm4bt)}₂ μ-Cl)₂] (1) (dm4bt = 2,2′-dimethyl-4,4′-bithiazole) was prepared from the reaction of CuCl₂ · 2H₂O with 2,2′-dimethyl-4,4′-bithiazole in methanol; [Cu(dm4bt)₂NO₃](NO₃) (2) was prepared from the reaction of Cu(NO₃)₂ · 3H₂O with 2,2′-dimethyl-4,4′-bithiazole in methanol. Both complexes were characterized by IR, UV–Vis spectroscopy, and single-crystal structure. The structure of 1 consists of centrosymmetric dimeric [{CuCl(dm4bt)}(μ-Cl)], in which two chloro ligands bridge the coppers forming a four-membered ring; a terminal chloride and a bidentate chelating bithiazole complete five coordination at each Cu(II) in a highly distorted trigonal-bipyramidal geometry. The mononuclear structure 2 consists of a Cu(II), two 2,2′-dimethyl-4,4′-bithiazoles, one monodentate nitrate and one uncoordinated nitrate in a highly distorted square pyramid.     

Synthesis and properties of trifluoromethylating steroid compounds

Trifluoromethyl steroids la,b; 2a,b; 3a,b have been synthesized by starting from estren 3,17-dicarbonyl-3,3-dimethyl ether (4) and dl-18-methyl-2(3)l5(10)-estra-diene-17-carbonyl-3-methyl ether (5),and by using trimthyltrifluoromethylsilane as the trifluoromethylating agent under the catalysis of tetrarnethylam-monium fluoride.The overall yields were 82%,76%; 54%,62%; and 27%,25%,respectively The α-configura tion of trifluoromethyl group of 17-position was determined by X-ray crystal diffraction method Compounds 1a,2a and 3a showed high affinity for rat uterus PRc.The test of biological activities of compounds 1b,2b and 3b is proceeding.     

Synthesis of a novel perylene diimide derivative and its charge transfer interaction with C_(60)

A novel organic electron acceptor, N,N′-dipyrimidinyl-3,4,9,10-perylene-tetracarboxylic diimide (DMP), was designed and synthesized. The molecular structure was characterized by FTIR spectrum and elemental analysis. By cyclic voltammetry measurements, DMP was found to possess a lower LUMO energy level than N,N′-diphenyl-3,4,9,10-perylene-tetracarboxylic diimide due to the stronger electron-withdrawing pyrimidinyl group than the phenyl group. Fluorescence quenching is observed in a dual-layer film consisting of a DMP layer and a C60 layer and was attributed to the charge transfer at the interface due to the energy level offset between DMP and C60.     

Synthesis,characterization and photophysical properties of homoleptic platinum(II) complexes with 2,2′-biimidazole-based ligands

Eight pairs of cis–trans isomeric homoleptic platinum(II) complexes based on N-alkyl- or aryl-substituted 2,2′-biimidazole ligands were synthesized, and their photophysical properties were investigated. The cis and trans isomers readily interconvert at slightly elevated temperature, implying that the activation barrier for this process is low. Single crystal X-ray diffraction analysis revealed that the complexes have an ideal square-planar geometry. Their UV–Vis spectra showed lower energy absorption bands in the range of 345–378 nm, which are assigned to the typical MLCT mixed with LC transitions. In frozen glass solution at 77 K and also in the powder state, these complexes exhibit green emission ranging from 440 to 540 nm with photoluminescence quantum yields of 3.3–24.4%. The emitting excited state is dominated by ³ππ* character with some contributions from ³MLCT according to the excitation spectra.     

Synthesis and characterization of complexes of the first transition series cations with 2,2′-biimidazole and 2,2′-biimidazolate

Mononuclear [M(hfacac)₂(H₂biim)] complexes, where M = Mn^II, Fe^II, Co^II, Ni^II, Cu^II or Zn^II, hfacac = hexafluoroacetylacetonate, H₂biim = 2,2-biimidazole; dinuclear K₂[M₂(acac)₄(-biim)] (M = Cu^II or Zn^II) and tetranuclear K₂[M₄(acac)₈( ₄-biim)] (M = Co^II or Ni^II) complexes have been prepared and characterized by chemical analysis, conductance measurements, i.r., electronic and e.p.r. spectroscopies and by magnetic susceptibility measurements (in the 2–300 K range). Mn^II, Fe^II and Co^II are in a high spin state. The e.p.r. spectra of Cu^II and Mn^II compounds have been recorded.     

Synthesis,structure and redox properties of mixed ligand complexes of trivalent ruthenium with deprotonated 2-carbamoylpyridine derivatives and 2,2′-bipyridine

Five mixed ligand complexes of trivalent ruthenium with general formula [Ru(L)(bpy)Cl₂], where L=p-substituted N-phenyl derivatives of 2-carbamoylpyridine and bpy=2,2′-bipyridine, have been synthesised and characterised. X-ray crystal structural characterisation of a representative complex, i.e. where L=2-(N-(4-nitrophenyl)carbamoyl)pyridine, shows that the amide-containing ligand coordinates to the ruthenium(III) centre via the pyridyl nitrogen and the amidato nitrogen, forming a five-membered chelate ring. The complexes are paramagnetic (low spin d⁵, S=1/2) and show a single signal in their EPR spectra in 1:1 dichloromethane–toluene solution at 77 K. In dichloromethane solution, these complexes show intense ligand to metal charge transfer transitions in the visible region. All the complexes display two cyclic voltammetric responses, a ruthenium(III)–ruthenium(IV) oxidation in the range from +0.63 to +0.93 V and a ruthenium(III)–ruthenium(II) reduction in the range from −0.63 to −0.73 V(vs ferrocene–ferrocenium couple). The potentials of both couples for all the complexes are found to be sensitive to the nature of the substituents present on the amide ligands, L.     

Synthesis and structure of 2,2′-diaminodiphenylditelluride bis-imines

Bis-imines of 2,2′-diaminodiphenylditelluride and 2-tosylamino (9a) and 2-hydroxybenzaldehyde (9b) were prepared and studied by X-ray diffraction, heteronuclear (¹H, ¹³C, ¹⁵N, and ¹²⁵Te) magnetic resonance, and quantum chemical calculations (Pbe1pbe/DGDZVP). According to the X-ray diffraction data, compound 9b in the crystal phase has nonsymmetrical structure: one of the tellurium atoms forms hypervalent bonding with the adjacent oxygen atom, while the second one is not involved in such interaction. The NMR study showed the symmetric molecular structure of imines 9a,b in DMSO-d₆ with the tellurium atoms interacting hypervalently with the C=N nitrogen atoms.     

Synthesis of P,N-2,2′-biphenyl derivatives with central chirality

Enantiopure 2-(dicyclohexylphosphino)-1,1′-biphenyl derivatives substituted in the 2′-position by a chiral amino group were prepared. For the compound bearing an acyclic chiral chain, the key step was a Suzuki coupling between bromobenzeneboronic acid and N-Boc-iodoaniline whereas an aromatic nucleophilic substitution allowed the introduction of a chiral pyrrolidine in the 2′-position of the biphenyl backbone. The efficiency of the P,N-biphenyl pyrrolidine derivatives as ligands in Pd-catalyzed arylaminations compares well with that of DavePhos ligand.     

Synthesis and acid-base properties of new β-diaminophosphoryl compounds

Russian Journal of Organic Chemistry -     

Synthesis and characterization of novel star-shaped pyridine cored compounds with alternating carbazole and triphenylamine moieties

Amorphous 2,4,6-trissubstituted pyridines containing three peripheral carbazole or two triphenylarnine and one carbazole moieties,respectively,have been synthesized and characterized.The properties of the compounds are investigated by UV-vis absorption,photoluminescence spectroscopy,thermal analysis as well as cyclic voltammetry.The results show that the compounds have high thermal stability,emit blue light.Also,the compounds possess the HOMO and LUMO energy levels comparable to those of NPB.The effects of different substituents on the electronic properties of the materials have been discussed.