Microwave spectra of [15n] and [13c] pyridines,quadrupole coupling constants,dipole moment and molecular structure of pyridine

The microwave spectra of two ring-substituted species of pyridine have been remeasured, and the spectra of the two remaining species investigated and assigned.¹⁴N quadrupole coupling splittings were analyzed and used to determine the quadrupole coupling constants, while the derived center frequencies were fitted to give improved values for the rotational constants.A complete substitution structure can now be presented.The dipole moment of pyridine was redetermined from Stark measurements in the spectrum of [¹⁵N]pyridine.     

An efficient ultrasonic-assisted synthesis of ethyl-5-(aryl)-2-(2-alkokxy-2-oxoethylidene)-7-methyl-3-oxo-3, 5-dihydro-2H-thiazolo [3, 2-a] pyrimidine-6-carboxylate derivatives

Dihydropyrimidinone derivatives were prepared by tri-component reaction of ethyl aceto acetate, aldehydes and thiourea in the presence of modified montmorillonite nanostructure as a catalyst and used as key intermediates for the synthesis of ethyl-5-(aryl)-2-(2-alkokxy-2-oxoethylidene)-7-methyl-3-oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyri midine-6-carboxylate derivatives with use of diethyl and dimethyl acetylene dicarboxylate by two methods: (a) in methanol as a solvent under ultrasonic irradiation at ambient temperature (b) in methanol as a solvent at ambient temperature (conventional magnetic stirring). Ultrasound-assisted synthesis provides excellent yields in short reaction times (15–25 min) at room temperature.     

Studies on metal-acetylene complexes : V. Crystal and molecular structure of bis(triphenylphosphine)(1-phenylpropyne)platinum(0), [P(C6H5)3]2(C6H5C CCH3)Pt0

The acetylene complex (P(C₆H₅)₃)₂Pt(C₆H₅CCCH₃) crystallizes in the monoclinic space group P2₁ with a = 14.840(4), b = 9.558(3), c = 13.553(4)Å and β = 102.74(2)°. The observed density of 1.47(2) g cm_-3 agrees with the value of 1.480 g cm_-3, calculated for M = 835.8 and Z = 2. Three dimensional X-ray diffraction intensity data were collected on an automatic four circle diffractometer using Mo radiation. The structure was solved by the heavy atom method and refined by Fourier and full matrix least-squares techniques on F. The final conventional agreement factor for the converged model is 0.042, using 2843 observations with I>3σ(I). The coordination geometry about the Pt atom is essentially trigonal, if the coordinated triple bond of the acetylene is assumed to occupy one coordination site. The acetylene ligand adopts a cis-bent configuration, with a mean departure from linearity of 40(1)°. The coordinated triple bond length is 1.277(25) Å. The plane of the phenyl substituent of the acetylene is inclined at an angle of 10.4° with the plane of the acetylene ligand. The mean Pt-(acetylene) distance is 2.029(15) Å. The structural results indicate that the acetylene is considerably perturbed on coordination, consistent with the observation that Δν(C≡C) is 478 cm_-1.     

Clathrate and inclusion compounds: Part V. An infrared and Raman study of the decomposition of the Hofmann aniline clathrates M(NH3)2Ni(CN)4.2C6H5NH2 {M = Cd(II) and Ni(II)}

The time-dependent changes which are observed in the infrared and Raman spectra of samples of the two Hofmann aniline clathrates M(NH₃)₂Ni(CN)₄.an₂ {M = Cd(II), Ni(II), an = C₆H₅NH₂} indicate the occurrence of a solid state ligand replacement reaction in which the aniline guest molecule replaces the coordinated ammonia to give Man₂Ni(CN)₄ as the final product. The rate of replacement is greater for the cadmium than for the nickel clathrate, and for both clathrates evacuation of the sample greatly increases the rate of replacement. The Man₂Ni(CN)₄ complexes can themselves act as host lattices forming clathrates containing guest molecules such as aniline.     

One-step synthesis of substituted 2-amino-4H-chromenes and 2-amino-4H-benzo[f]chromenes. Molecular and crystal structure of 2-amino-3-cyano-6-hydroxy-4-phenyl-4H-benzo[f]chromene

Substituted 2-aminochromenes were synthesized by three-component condensation of aromatic aldehydes, derivatives of cyanoacetic acid, and phenols or naphthols. The molecular and crystal structure of 2-amino-3-cyano-6-hydroxy-4-phenyl-4H-benzo[f]chromene was established by X-ray diffraction analysis.     

A novel chain-like molybdenum phosphate: hydrothermal synthesis,crystal structure and characterization of [NH3(CH2CH2)2NH3]3[NH3(CH2CH2)2NH2]-Na5[Mo6O12(OH)3(PO4)(HPO4)3]2·4H2O

A novel organic/inorganic hybrid molybdenum phosphate, [NH₃(CH₂CH₂)₂NH₃]₃[NH₃(CH₂CH₂)₂NH₂]Na₅-[Mo₆O₁₂(OH)₃(PO₄)(HPO₄)₃]₂·4H₂O (1), involving molybdenum presented in V oxidation, has been hydrothermally prepared and characterized by elemental analysis, i.r., u.v.–vis., x.p.s., t.g. and single crystal X-ray diffraction. The structure of the title compound (1) may be considered to consist of two [Mo₆O₁₂(OH)₃(PO₄)(HPO₄)₃] units bonded together with NaO₆ octahedra, forming dimers. Further, these dimers connect with each other through four Na⁺ cations as bridges, giving rise to novel one-dimensional chain-like skeleton. Piperazines exist among inorganic chains acting as charge balancing cations.     

Synthesis of 6-amino-4-aryl-5-cyano-3-(3-cyanopyridin-2-ylthiomethyl)-2,4-dihydropyrano[2,3-c]pyrazoles and their hydrogenated analogs. Molecular structure of 6-amino-5-cyano-3-(3-cyano-4,6-dimethylpyridin-2-ylthiomethyl)-4-(2-nitrophenyl)-2,4-dihydropyrano[2,3-c]pyrazole

Substituted 3-hydroxypyrazoles, which were prepared based on ethyl esters of substituted 4-(pyridin-2-ylthio)- or 4-(1,4-dihydropyridin-2-ylthio)acetoacetic acids and hydrazine hydrate, were used in the synthesis of 6-amino-4-aryl-5-cyano-3-(pyridin-2-ylthiomethyl)-2,4-dihydropyrano[2,3-c]pyrazoles. The molecular and crystal structure of 6-amino-5-cyano-3-(3-cyano-4,6-dimethylpyridin-2-ylthiomethyl)-4-(2-nitrophenyl)-2,4-dihydropyrano[2,3-c]pyrazole was established by X-ray diffraction analysis.     

4-hydroxy-2-quinolones. 114. Synthesis and structure of 6-R-5-hydroxy-2,4-dioxo-2,3,4,6-tetrahydrobenzo-[<Emphasis Type="Italic">c</Emphasis>][2,7]naphthyridine-1-carbonitriles

Hydration of ethyl 1-R-4-dicyanomethyl-2-oxo-1,2-dihydroquinoline-3-carboxylate gives the corresponding substituted cyanoacetamides which are readily and quantitatively cyclized to 6-R-5-hydroxy-2,4-dioxo-2,3,4,6-tetrahydrobenzo[c][2,7]naphthyridine-1-carbonitriles in the presence of aqueous base. For Communication 113 see [1]. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 726–735, May, 2007.     

195Pt, 119Sn and 31P NMR studies of alkyl,aryl and acyl trichlorostannate complexes of platinum(II). The crystal structure of trans-[Pt(SnCl3)(COC6H5)(PEt3)2]

¹⁹⁵Pt, ¹¹⁹Sn and ³¹P NMR characteristics of the complexes trans-[Pt(SnCl₃)(carbon ligand)(PEt₃)₂] (1a-1e) are reported, (carbon ligand = CH₃ (1a), CH₂Ph (1b), COPh (1c), C₆Cl₅ (1d), C₆Cl₄Y (e); Y = meta- and para-NO₂, CF₃, Br, H, CH₃, OCH₃, or Pt(SnCl₃)(PEt₃)₂. The values of ¹J(¹⁹⁵Pt, ¹¹⁹Sn) vary from 2376 to 11895 Hz with the COPh ligand having the smallest and the C₆Cl₅ ligand the largest value, making a total range for this coupling constant, when the dimer syn-trans-[PtCl(SnCl₃)(PEt₃)]₂ is included, of ca. 33000 Hz. In the meta- and para-substituted phenyl complexes ¹J(¹⁹⁵Pt, ¹¹⁹Sn) (a) is greater for electron-withdrawing substituents, (b) varies more for the meta-substituted derivatives (5634 to 7906 Hz) than for the para analogues (6088 to 7644 Hz) and (c) has the lowest values when the Pt(SnCl₃)(PEt₃)₂ group is the meta- or para-substituent. The direction of the change in ¹J(¹⁹⁵Pt, ¹¹⁹Sn) is opposite to that found for ¹J(¹⁹⁵Pt, ¹¹⁹P). For the aryl complexes linear correlations are observed between δ(¹¹⁹Sn), ¹J(¹⁹⁵Pt, ¹¹⁹Sn), ¹J(¹⁹⁵Pt, ³¹P), ¹J(¹¹⁹Sn, ³¹P) and the Hammett substituent constant σⁿ. δ(¹¹⁹Sn) and ¹J(¹⁹⁵Pt, ¹¹⁹Sn) are related linearly to v(Pt-H) in the complexes trans-[PtH(C₆H₄Y)(PEt₃)₂]; δ(¹¹⁹Sn) and δ(¹H) (hydride) are also linearly related. Based on ¹J(¹⁹⁵Pt, ¹¹⁹Sn), the acyl ligand is suggested to have a very large NMR trans influence. The differences in the NMR parameters for (1a-e) are rationalized in terms of differing σ- and π-bonding abilities of the carbon ligands.The structure of 1c has been determined by crystallographic methods. The complex has a slightly distorted square planar geometry with trans-PEt₃ ligands. Relevant bond lengths (Å) and bond angles (°) are: PtSn, 2.634(1), PtP, 2.324(4) and 2.329(4), PtC, 2.05(1); PPtP, 170.7(6), SnPtC, 173.0(3), SnPtP, 92.1(1), 91.7(1), PPtC, 88.8(4) and 88.3(4). The PtSn bond separation is the longest yet observed for square-planar platinum trichlorostannate complexes, and would be consistent with a large crystallographic trans influence of the benzoyl ligand. The PtSn bond separation is shown to correlate with ¹J(¹⁹⁵Pt, ¹¹⁹Sn).     

Synthesis of 1,1′-di-t-butylstannocene and its reaction with trifluoroborane. The crystal and molecular structure of η5-(CH3)3CC5H4Sn+BF4−

The reaction of Li(CH₃)₃CC₅H₄ with SnCl₂ in THF affords 1,1′-di-t-butylstannocene in 78% yield as an air-sensitive oil. ¹H and ¹³C NMR spectra are consistent with a pentahapto-structure. Mössbauer parameters of the stannocene and its trimethylsilyl counterpart match closely those of known stannocenes and neither compound appears to undergo oligomerization. The reaction of 1,1′-di-t-butylstannocene with BF₃ in CH₂Cl₂ affords η⁵-(CH₃)₃CC₅H₄Sn⁺ BF₄^? and other uncharacterized product(s) thought to involve tetracoordinate tin. The structure of η⁵-(CH₃)₃CC₅H₄Sn⁺ BF₄^? was determined by single crystal X-ray diffraction (orthorhombic,Pbcn, (T 25°C), a 18.423(3), b 11.723(1), c 11.044(2) Å, Z Å, m.p. 95–96°C, colorless, Mo-K_α, R = 0.043).     

Transition-metal complexes of two valence tautomers of a bulky phenoxide, 2,6-Bu-t2-4-MeC6H2O− (ArO−); preparation and crystal and molecular structure of a phenoxytitanium(III) and a cyclohexadienonylrhodium(I) complex, [Ti(η-C5H5)2 OAr] and [Rh(ArO-η5)(PPh3)2]

The 2,6-di-t-butyl-4-methylphenoxo ligand (ArO^?) is ambidentate, giving rise to the O-bonded 15-electron d¹ [Ti(η-C₅H₅)₂OAr] and the η⁵ -[C(2)-C(6)]-bonded 18-electron d⁸ complex [Rh(ArO-η⁵)(PPh₃)₂], obtained from [{Ti(η-C₅H₅)₂Cl}₂]-LiO Ar and [Rh{N(SiMe₃)₂}(PPh₃)₂]-ArOH, respectively; the average TiC(η) distance is 2.362(10) Å, TiO 1.892(2) Å, and O:C(of Ar) 1.352(3) Å, and TiOC 142.3(2)°; in the Rh^I complex, C(2)C(6) are coplanar (with CC(av.) 1.38(2) Å). C(1)O 1.28 Å, and Rh to C(2) C(6) bond lengthsare in the range 2.19–2.65 Å.     

Design,synthesis and biological evaluation of 5-(2-(4-(substituted benzo[d]isoxazol-3-yl)piperazin-1-yl)acetyl)indolin-2-one and 5-(2-(4-substitutedpiperazin-1-yl)acetyl)indolin-2-one analogues as novel anti-tubercular agents

A series of thirty-six novel 5-(2-(4-(benzo[d]isoxazol-3-yl)piperazin-1-yl)acetyl)indolin-2-one and 5-(2-(4-substitutedpiperazin-1-yl)acetyl)indolin-2-one analogues were synthesized, characterized and screened for their in vitro anti-tubercular activity against Mycobacterium tuberculosis H37Rv strain. These compounds exhibited minimum inhibitory concentration between 1.56 and 50 μg/mL. Among these derivatives, compounds 10c, 10d, 10j, 10o and 10v (MIC 6.25 μg/mL) displayed moderate activity, while compounds 10e, 10l, 10q, 10w,10x, 12d, 12e and 12i (MIC 3.12 μg/mL) showed good anti-tubercular activity and compounds 10f, 10k, 10p, 10r, 12f, 12j and 12k (MIC 1.56 μg/mL) exhibited excellent anti-tubercular activity. In addition, MTT assay was accomplished on the active analogues of the series against mouse macrophage (RAW 264.7) cells to evaluate the cytotoxic effect of the newly synthesized compounds and selectivity index of the compounds was determined.     

Intramolecular cyclization of ketene containing both acyl andN-alkylimidoyl substituents. Synthesis and crystal and molecular structure of 3-benzoyl-5-phenyl-2H,4H-furo[3,2-c] isoquinolin-2-one

Thermal decarbonylation of 1-benzyl-4,5-dibenzoyl-2,3-dihydropyrrole-2,3-dione yields benzoyl[N-benzyl(phenylglyoxalimidoyl)]ketene. The latter undergoes intramolecular cyclization to 3-benzoyl-5-phenyl-2,3,4,5-tetrahydrofuro[3,2-c]isoquinolin-2-one. Which is oxidized to 3-benzoyl-5-phenyl-2H,4H-furo[3,2-c]isoquinolin-2-one under the reaction conditions. The crystal and molecular structure of the title compound was studied by X-ray structural analysis. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 563–565, March, 1997.     

Structural chemistry of bimetallic hydride complexes of titanium and aluminium: I. Crystal and molecular structure of [(η5-C5H5)2,Ti(μ-H)2AlH2]2(CH3)2NCH2CH2N(CH3)2C6H6

The structure of a titanium aluminium hydride complex of composition [(C₅H₅)₂TiAlH₄]₂(CH₃)₂NC₂H₄N(CH₃)₂C₆H₆ has been determined by X-ray diffraction. The complex forms triclinic crystals with unit cell dimensions a = 8.406(2), b = 10.117(2), c = 11.269(3) Å; α = 112.01(2)°, β = 109.25(2)°, γ = 87.04(2)°, space group P$\text{1}$, Z = 2 and density d = 1.21 g/cm³. The structure was refined to give a discrepancy index R = 0.056. The crystals are composed of centrosymmetric molecules of (Cp₂TiAlH₄)₂TMEDA (Cp = η⁵-cyclopentadienyl) and molecules of crystal benzene. Two moieties of Cp₂TiH₂AlH₂ are linked by a tetramethylethylenediamine molecule (r_AlN 2.11 Å). The aluminium atom is bonded to a titanium atom by a double hydride bridge (r_AlH b = 1.8, 1.6 Å, r_TiH b = 1.6 Å), and has trigonal bipyramidal stereochemistry, [H₄N] (r_AlH t = 1.6 Å).     

CS2在Cu-S键中的插入反应的研究3:[Cu(S2CSC6H2Bu3^t-2,4,6]4.4C2H5OH的合成与晶体结构

2,4,6-三特丁基硫酚铜[Cu(SC6H2Bu3^t-2,4,6-)]n与CS2的反应产物, 用CS2-乙醇重结晶得黄色晶体, 经X射线单晶衍射法测定, 其结构为[Cu(S2CSC6H2Bu3^t-2,4,6-)].晶体属四方晶系, 空间群142d.a=b=1.7079(3)nm,c=3.5228(10)nm, V=10.275(6)nm3, Dc=1.19gcm^-3, Z=4.1863个衍射点参与修正,R=0.0559.四个铜原子形成变形四面体, CS2在全部四个Cu-S键中插入, 形成硫代黄原酸配体(RSCS2^-).配体中两个硫原子参与配位, 其中一个S桥连两个Cu原子, 另一个S端位于第三个Cu原子。每个Cu原子都采取平面三配位方式。CS2插入形成的CS2基团基本平面, C-S平均键长为0.1712nm。本文还对CS2, 在Cu-S和Ag-S键中插入反应产物的结构特点及影响反应的因素进行了讨论。     

Reaction of 2-Oxoindolin-3-Ylidene Derivatives with Heterocyclic Enamines. A Convenient One-Pot Synthesis of Pyrimido [5,4:5',6']Pyrido[2,3-b]-Indole-2,4-Dione and Spiro Indolin-2-One-3,5'-Pyrido [2,3-d] Pyrimidines

The reaction of 6-aminouracils 2a, b with 2-oxoindolin-3-ylideneacetophenones 1a-h afforded Pyrimido[5,4:5', 6'] pyrido-[2, 3-b] indole- 2,4-diones 3 a-k via a regiospecific Michael addition, followed by cyclization. Alternatively, the reaction of 2a with 2-oxoindolin-3-ylidenemalononitriles 6a, b gave rise to regiospecific formation of spiro indolin-2-one-3, 5'-pyrido[2,3-d]pyrimidines 7a,b.     

Azirino[c]imidazolyl ylides in the domino reaction of 2,2-dialkyl-4,6-diaryl-1,3-diazabicyclo[3.1.0]hex-3-enes with dichlorocarbenes. Synthesis of (1RS,5SR, 6RS)-4-(alk-1-enyl)-1,5-diaryl-3,7,7-trichloro-2,4-diazabicyclo[4.1.0]hept-2-enes

The reaction of 2,2-dialkyl-4,6-diaryl-1,3-diazabicyclo[3.1.0]hex-3-enes with dichlorocarbene to give (1RS,5SR,6RS)-4-(alk-1-enyl)-1,5-diaryl-3,7,7-trichloro-2,4-diazabicyclo[4.1.0]hept-2-enes has been studied. Quantum-chemical calculations using the DFT B3LYP/6-31G(d) method have confirmed that the mechanism of the reaction includes the formation of azirino[c]imidazolium ylides and coordinated opening of the imidazole and aziridine rings with subsequent cyclization and dichloropropane formation. Dedicated to the respected memory of A. A. Potekhin __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 730–740, May, 2008.     

A novel mononuclear gold(I) complex: Synthesis and x-ray structure of [Au{P(C6H5)3}3][SiF5] · 1.5 CH2Cl2

Tris(triphenylphosphine)gold(I)-pentafluorosilicate(IV) ([Au{P(C₆H₅)₃}₃][SiF₅]) was prepared and the structure was determined by single crystal x-ray diffraction. The complex crystallizes in the triclinic space group P1 (No. 2). The lattice constants are a = 14.634(2) Å, b = 17.180(2) Å, c = 22.212(3) Å, α = 86.48(1)°, β = 78.95(1)°, γ = 83.99(1)°. Number of molecules per cell: Z = 4. The gold atoms are coordinated to three triphenylphosphine ligands to form the trigonal planar cation [Au{P(C₆H₅)₃}₃]⁺. Separated from the cation is the [SiF₅]^? anion which is regular trigonal bipyramidal coordinated. No interactions between the fluorine atoms and the gold atoms were observed.