Synthesis, structure, and electronic calculations of group VII substituted pyridazines

A series of 5,6-fused ring cyclopentadienyl tricarbonyl manganese and rhenium complexes, [M(CO)₃{η ⁵-1,2-C₅H₃(1,4-(R)₂N₂C₂}] (2a–3d) were isolated by employing an off-metal ring closure route. Reacting thallium cyclopentadienide (Cp) salts (1a–d) with [MBr(CO)₅] (M = Mn, Re) provided pyridazyl complexes (2a–3d) in high yield (75–99 %). Spectroscopic characterization (NMR, IR, MS) confirmed the identity of the desired organometallic pyridazines. The off-metal synthetic pathway employed did improve upon the isolation of these complexes as compared to previously reported routes. The molecular and electronic structure of complexes 2a–3d and their optimal energy structures have been characterized with quantum chemistry calculations. Vibrational frequencies calculated were compared to their experimental counterparts. The excited state calculations predict that the dominant low-energy transition involves a ligand-to-metal charge transfer.     

Synthesis,Characterization, and Structure of Some New Substituted 5,6-Fused Ring Pyridazines

Pyridazines are an important class of heterocyclic compounds as a result of their materials and commercial applications. The synthesis of 5,6-fused ring pyridazines 2a–h from 1,2-diacylcyclopentadienes (fulvenes) 1a–h is described herein. This route was quite general, and features an efficient and convenient two-step synthesis of a series of 5,6-fused ring 1,2-disubstituted pyridazines using enolized 1,2-disubstituted fulvenes in a methanolic solution of hydrazine. Full characterization of newly formed fulvene 1e and pyridazines 2a–h are reported. Single-crystal X-ray analysis confirms the molecular structure of pyridazine 2f, which displayed the expected pyridazine fused to the cyclopentadienyl moiety. Adding to their real world capabilities in electronic devices, compounds 2a–h display reasonably high stability in solution and in air at room temperature.

Synthesis, crystal structure, and electronic structure of RbVSe2

RbVSe₂ has been synthesized at 773 K through the reaction of V and Se with a Rb₂Se₃ reactive flux. The compound crystallizes in the orthorhombic space group D_2h²⁴-Fddd with 16 formula units in a cell of dimensions , , and at . The structure possesses infinite one-dimensional chains of edge-sharing VSe₄ tetrahedra separated from the Rb⁺ ions. These chains distort slightly to chains. The V-V distance within these chains is 2.8362(4) Å. First-principles total energy calculations indicate that a non-magnetic configuration for the V³⁺ cations is the most stable.     

Synthesis and structure of some group VII 1,2-diacyl cyclopentadiene complexes and their pyridazine derivatives

A series of 1,2-diacyl cyclopentadienyl tricarbonyl manganese and rhenium complexes, [M(CO)₃{η⁵-1,2-C₅H₃(CO-(R)₂}] (3a–c and 4a–b), were isolated utilizing a straightforward, 3-step route. The synthetic pathway began with a 1,2-diacyl cyclopentadiene (fulvene), followed by the formation of its corresponding thallium salt and transmetallation with the appropriate pentacarbonyl metal bromide. X-ray crystallographic analysis and high-accuracy mass spectrometry confirmed the structures of the both the 4-methoxyphenyl and 4-chlorophenyl diacyl rhenium complexes, [Re(CO)₃{η⁵-1,2-C₅H₃(CO-(4-OCH₃)C₆H₄)₂}] (4a) and [Re(CO)₃{η⁵-1,2-C₅H₃(CO-(4-Cl)C₆H₄)₂}] (4b). Diacyl complexes 3a–c and 4a–b were then ring-closed with hydrazine hydrate to form their corresponding pyridazine complexes, [M(CO)₃{η⁵-1,2-C₅H₃(1,4-(R)₂N₂C₂}] (5a–c and 6a–b), in good yields (60–83%). The pyridazyl ligands were found to be relatively labile, and recrystallization of the target complexes 5a–c and 6a–b afforded only the free pyridazine ligands.     

Synthesis, structure and luminescence property of the ternary and quaternary europium complexes with furoic acid

A ternany europium complex with furoic acid (α-FURA) and 1,10-phenanthroline(phen), [Eu(α-FURA)₃phen]H₂O(I) and a quaternary europium furoate complex with 1,10-phenanthroline and nitrate, Eu(α-FURA)₂NO₃phen(II) were synthesized and characterized by X-ray diffraction. The two europium ions in each of the complexes (I) and (II) are held together by four carboxylato groups with the two modes, namely bidentate bridging and tridentate bridging, and each europium ion is further bonded to two nitrogen atoms from 1,10-phenanthroline and one chelated bidentate furoate group for the complex (I) and one chelated nitrato group for the complex (II), making a coordination number of 9. Luminescence spectra observed at 77 K show that the europium ion site in the crystals of the complexes (I) and (II) has low symmetry and lifetimes of the solid complexes (I) and (II) are 1.13 and 1.20 ms, respectively.     

Synthesis and crystal structure study of 2′-Se-adenosine-derivatized DNA

The selenium derivatization of nucleic acids is a novel and promising strategy for 3D structure determination of nucleic acids.Selenium can serve as an excellent anomalous scattering center to solve the phase problem,which is one of the two major bottlenecks in macromolecule X-ray crystallography.The other major bottleneck is crystallization.It has been demonstrated that the incorporated selenium functionality at the 2′-positions of the nucleosides and nucleotides is stable and does not cause significant st...     

Synthesis,structure, and rearrangements of new tricarbonylchromium complexes of substituted heptalenes

Reactions of 1,2,5,6,8,10-hexamethylheptalene (1) and its bond isomer, 1,4,5,6,8,10-hexamethylheptalene (2), with tricarbonylchromium complexes L{in3}Cr(CO){in3} (L=NH{in3} and Py) have been investigated. Thermodynamically less stable complex 1 exhibits higher reactivity with respect to Py{in3}Cr(CO){in3}/BF{in3} · Et{in2}O under the conditions of Öfele's reaction than complex2. At 10–30 °C, the Cr(CO){in3} group is coordinated to the asymmetrically substituted ring, which is accomplished by the shift of double bonds in the ligand, to afford tricarbonyl-[1,4,5,6,8,10-hexamethyl-{su6}-(10a, 1–5)heptalene]-chromium (6) as the only mononuclear complex. Under more drastic conditions (Raush's reaction, 80 °C),1 2 interconversion proceeds faster than the reaction of individual bond isomers with coordinatively unsaturated hot particles (solv){inn}Cr(CO){in3}. In this case, all of the four possible isomeric mononuclear complexes (6–9) and two binuclear complexes (10 and 11) are formed. The structures of complexes 6–11 have been studied by NMR and mass spectrometry, the structure of6 has been established by X-ray diffraction analysis. Heating a solution of6 in octane at 115 °C results in the isomerization of6 into complex7 through the intracycle 1,2-shift of the Cr(CO){in3} group and also in its conversion into complex8, which is the first example of interring {su6}{su6}-haptotropic rearrangement in nonplanar seven-membered -systems.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2220–2226, December, 1994.We would like to thank N. S. Kulikov for measuring mass spectra and L. A. Aslanov for helpful discussion of the results of X-ray diffraction analysis.The Research Group from the Moscow State University gratefully acknowledges the support of this work by the International Science Foundation (Grant No. MQ 5000) and the Russian Foundation for Basic Research (Project No. 94-03-08325).     

Synthesis, structure, and electronic structure of K2CuSbS3

The new compound K₂CuSbS₃ has been synthesized by the reaction of K₂S, Cu, Sb, and S at 823 K. The compound crystallizes in the Na₂CuSbS₃ structure type with four formula units in space group P2₁/c of the monoclinic system in a cell at 153 K of a=6.2712 (6) Å, b=17.947 (2) Å, c=7.4901 (8) Å, β=120.573 (1)°, and V=725.81 (12) Å³. The structure contains two-dimensional layers separated by K atoms. Each layer is built from CuS₃ and SbS₃ units. Each Cu atom is pyramidally coordinated to three S atoms with the Cu atom about 0.4 Å above the plane of the S atoms. Each Sb atom is similarly coordinated to three S atoms but is about 1.1 Å above its S₃ plane. First-principles calculations indicate an indirect band gap of 1.9 eV. These calculations also indicate that there is a bonding interaction between the Cu and Sb atoms. An optical absorption measurement performed with light perpendicular to the (0 1 0) crystal face of a red block-shaped crystal of K₂CuSbS₃ indicates an experimental indirect band gap of 2.2 eV.     

Bonding analysis and electronic structure of transition metal-benzoquinoline complexes: A theoretical study

The geometric and electronic structures of a series of hypothetical compounds of the types CpM(C₁₃H₉N) and (CO)₃M(C₁₃H₉N) (M = first row transition metal and C₁₃H₉N = 7,8-benzoquinoline) have been investigated by means of density functional theory (DFT). The benzoquinoline ligand can bind to the metal through η¹-η⁶ coordination modes, adopting structures of types a, b and c, in agreement with the electron count and the nature of the metal. In the investigated species, the most favored closed-shell count is 18-MVE, except for the Ti and V models which prefer the open-shell 16-MVE configuration. This study has shown the difference in the coordination ability of this heteropolycyclic ligand and coordination of the inner C₆ ring is less favored than the outer C₆ and C₅N rings, in agreement with the π-electron density localization.     

Inclusion complexes of the natural product gossypol. Clathrate type inclusion complexes of gossypol with carbonyl group containing guests

The crystal structures of 2:1 inclusion complexes of gossypol with methyl propionate (GPMEP) and ethyl acetoacetate (GPEAA) have been determined by X-ray structure analysis. The crystals of GPMEP, C₃₀H₃₀O₈l/2 C₄H₈O₂, are monoclinic, space groupC2/c,a=11.079(3),b = 30.724(7), c = 16.515(5) Å, = 90.46(2)°,V = 5621(3) Å,Z = 8,D _x = 1.33 g cm^–3. The structure has been refined to the finalR value of 0.059 for 1899 observed reflections. The crystals of GPEAA, C₃₀H₃₀O₈l/2 C₆H₁₀O₃, are monoclinic, space groupC2/c,a=11.095(2),b=30.604(9),c = 16.955(5) Å, = 88.27(2)°,V = 5754(3) Å,Z = 8,D _x = 1.35 g cm^–3. The structure has been refined to the finalR value of 0.056 for 2502 observed reflections.In contrast to previously investigated inclusion complexes of gossypol the host molecules do not form centrosymmetric dimersvia hydrogen bonds. In the crystal structures the racemic gossypol is separated into enantiomers forming alternating bimolecular layers. Nearly perpendicular to these chiral bilayers run elongated cavities enclosed on each side by layers of opposite chirality. The surface of these layers is hydrophobic, the polar groups are hidden inside the layer. Guest molecules which are hydrogen bonded to the host are included in cylindrically shaped cavities. Possible hydrogen bonds between host and guest are analysed for this isostructural class of complexes.     

Synthesis, structural characterization of some germanium substituted chiral diethyltin derivatives

Some new bimetallic carboxylates of tin and germanium with general formula where R¹ = m-CH₃C₆H₄, p-CH₃C₆H₄, C₆H₅, R² = o-CH₃C₆H₄, p-CH₃C₆H₄, o-CH₃OC₆H₄, C₆H₅, CH₃, have been prepared by the condensation reaction of diethyltin oxide and triarygermyl(substituted)propanoic acid in 1:2 mole ratio, respectively, and characterized by multinuclear (¹H, ¹³C, ¹¹⁹Sn) NMR, ^119mSn Mössbauer and IR spectroscopy. The X-ray crystal structure of the ligand I₄ [(C₆H₅)₃GeCH(o-CH₃OC₆H₄)CH₂COOH] delineate four coordinated germanium atom with a peculiarity of having a molecule of solvent (CHCl₃). The chiral center in the synthesized compounds was identified on the basis of ¹H NMR data and measurements of angle of rotations.     

Single-crystal growth, crystal and electronic structure of NaCoO2

Single crystals of NaCoO₂ have been successfully synthesized for the first time by a flux method at 1323 K. A single-crystal X-ray diffraction study confirmed the trigonal space group and the lattice parameters , . The crystal structure has been refined to the conventional values R=1.9% and wR=2.1% for 309 independent observed reflections. The electron density distribution of NaCoO₂ has been studied by the maximum entropy method (MEM) using single-crystal X-ray diffraction data obtained at 298 K. From the results of the MEM analysis, the strong covalent bonding was clearly observed between Co and O atoms, while no bonding was observed around Na atoms. We also calculated the electron density of NaCoO₂ by first principles calculations. The electron density obtained experimentally is in good agreement with the theoretical one.     

Synthesis and structure of lanthanide complexes with large-bite diphosphine dioxide ligands

Three large-bite diphosphine dioxide ligands were reacted with lanthanide salts to yield either molecular or polymeric complexes. The two flexible ligands gave bischelate complexes of general formulae [Ln(dppfO₂)₂Cl_x(NO₃)_2−x][FeCl₄] and [Ln(dppdO₂)₂(NO₃)₂]NO₃, where dppfO₂ and dppdO₂ are bis(diphenylphosphoryl)ferrocene and bis(diphenylphosphoryl)diphenyl ether, respectively. Reactions of the rigid bis(diphenylphosphoryl)benzene (dppbO₂) with lanthanide salts yielded linear coordination polymers of a 1:1.5 metal-to-ligand stoichiometry. The compounds were studied by single crystal X-ray diffraction, IR spectroscopy, mass spectrometry, and TG/DSC techniques.     

Synthesis, spectroscopic characterization and electronic structure of some new Cu(I) carbene complexes

Reaction of oligomeric Cu(I) complexes [Cu(Μ-S-C(=NR)(O-Ar-CH₃)]_n with Lewis acids gave Cu(I) carbene complexes, which were characterized by¹H and¹³C NMR spectroscopy. Cu(I) carbene complexes could be directly generated from RNCS, Cu(I)-OAr and Lewis acids; this method can be used to prepare Cu(I) carbene complexes with different substitutents on the carbene carbon. The complexes were unreactive towards olefins and do not undergo cyclopropanation. Electronic structure calculations (DFT) show that the charge on the carbene carbon plays an important role in controlling the reactivity of the carbene complex.     

Synthesis, structure and spectral study of two types of novel fluorescent BF2 complexes with heterocyclic 1,3-enaminoketone ligands

Two types of novel BF₂ complexes are readily obtained by the reaction of BF₃OEt with 3-(2-oxo-2-arylethylidene)-3,4-dihydro-1H-quinoxalin-2-ones or 3-(2-oxo-2-arylethylidene)-3,4-dihydrobenzo[1,4]oxazin-2-ones, respectively in refluxing acetic acid/toluene solvent mixture. The complexes are confirmed by elemental analysis, FT-IR, ¹H, ¹³C, ¹¹B, ¹⁹F NMR and one of them is executed its X-ray crystallographic study. The outstanding photophysical properties of these complexes are determined by UV–vis absorption and fluorescence emission spectroscopy.     

Synthesis, structure, band gap, and electronic structure of CsAgSb4S7

The compound CsAgSb₄S₇ has been synthesized by the reaction of the elements in a Cs₂S₃ flux at 773 K. The compound crystallizes in a new structure type with eight formula units in space group C2/c of the monoclinic system in a cell at 153 K of dimensions , , , β=97.650(1)°, and . The structure contains two-dimensional layers separated by Cs atoms. Each layer is built from edge-sharing one-dimensional and chains. Each Ag atom is tetrahedrally coordinated to four S atoms. Each Sb³⁺ center is pyramidally coordinated to three S atoms to form an SbS₃ group. CsAgSb₄S₇ is insulating with an optical band gap of 2.04 eV. Extended Hückel calculations indicate that the band gap in CsAgSb₄S₇ is dominated by the Sb 5s and S 3p states above and below the Fermi level.     

Inclusion complexes of the natural product gossypol. Strong influence of the guest on the host structure in channel-type isostructural inclusion complexes of gossypol

The crystal structures of 1 : 1 inclusion complexes of gossypol with tetrahydrofuran (GPTHF), cyclohexanone (GPCHN) and butanal (GPBTA) have been determined by X-ray structure analysis. The crystals of GPTHF are triclinic, space group P,a = 10.788(2),b = 10.979(3),c = 13,880(2) Å, = 80. 11(2), = 103.87(1), = 77.96(2)°,V = 1517.8(6) ų,Z = 2,R = 0.052 for 2701 observed reflections. The crystals of GPCHN are triclinic, space groups P,a = 10.803(4),b = 11.157(5),c = 15.428(6) Å, = 108.75(3), = 106.93(3), = 103.34(3)°,V = 1573(1) ų,Z = 2,R = 0.071 for 1879 observed reflections. The crystals of GPBTA are triclinic, space group P,a = 10.190(2),b = 11.335(1),c = 14.665(2) Å, = 73.04(1), = 103.74(1), = 81.07(1)°,V = 1529.9(5) ų,Z = 2,R = 0.068 for 2964 observed reflections. Crystal data for another 13 isostructural inclusion complexes are given.[/p]In this isostructural group of complexes guest molecules are accommodated in channels and are hydrogen bonded to the host molecules via an 0(1)-H....O(1) hydrogen bond. The molecular association changes significantly with the shape and size of the guest component. In GPTHF centrosymmetric dimers of gossypol formedvia O(5)-H...O(3) hydrogen bonds are associated in columns via a weak O(4)-H...O(8) hydrogen bond. In GPCHN the latter bond disappears as the distance O(4)-O(8) is increased to 3.73 Å. In GPBTA the O(5)-H...O(3) bond is replaced by three centre hydrogen bonds O(5)-H...O(2) and O(3)-H...O(5), and a centrosymmetric dimer of a new type is formed. These dimers are further connected by two weak hydrogen bonds to form columns. The butanal molecule interacts with the host structure via two hydrogen bonds. This indicates that a guest component can activate or deactivate different functional groups of the host in channel inclusion complexes of gossypol for hydrogen bond formation.     

Synthesis,structure and properties of some copper(II) complexes containing an ONO donor Schiff base and substituted imidazole ligands

Five new mixed ligand coper(II) complexes, viz. [Cu(SAA)(H₂O)] (1), [Cu(SAA)(MeImH)] (2), [Cu(SAA)(EtImH)] (3), [Cu(SAA)(BenzImH)] (4) and [Cu(SAA)(MebenzImH)] (5), where SAA = salicylideneanthranilic acid, MeImH = 2-methylimidazole, EtImH = 2-ethylimidazole, BenzImH = benzimidazole, MebenzImH = 2-methylbenzimidazole, have been synthesized and characterized by means of elemental analysis, FAB mass spectrometry, magnetic susceptibility, X-band EPR, electronic spectroscopy, IR and cyclic voltammetry. The frozen solution EPR spectra of the complexes have shown axial features. Single crystal X-ray analysis of 2 and 3 has revealed the presence of a distorted square planar geometry (N₂O₂) in the complexes. The superoxide dismutase (SOD) activity of the present complexes has also been measured and discussed.     

一些大取代二茂铁三碘化物的合成和结构分析

合成了一系列大取代二茂铁三碘化物,通式为(RC~5H~4)~2FeI~3。通过元素分析,红外光谱,质谱,顺磁共振谱,穆斯堡尔谱和电导率对这些化合物进行了表征。测定了化合物[CH~2(CH~2)~3C(2-CH~2C~5H~4N)C~5H~4]~2FeI~4.H~2O的晶体结构,该晶体属三斜晶系,P-1空间群,晶胞参数:a=0.9593(1),b=1.3999(2),c=1.4537(2)nm。α=109.64(1),β=97.25(1),γ=104.69(1)ⅲ。V=1.7299nm^3,Mr=1030.13,Dx=1.98g/cm^3,Z=2。结果表明,取代二茂铁被碘部分氧化,导致中心金属铁表现为混合价态;由于茂环上大取代基的影响,使得I~3^-与I~3^-之间未能形成碘链,因此这些化合物的电导率很低。