Reaction of thiourea and substituted thioureas with 1,3-dibromopropyne

4-Bromomethylidene-2-imino(phenylimino, acetylimino)-1,3-thiazolidine hydrobromides and 4-bromomethylidene-2-acetylimino-1,3-thiazolidine are synthesized by the reaction of thiourea, N-phenylthiourea, N,N′-diphenylthiourea and N-acetylthiourea with 1,3-dibromopropyne in glacial acetic acid, absolute methanol, acetonitrile at 20°C or upon heating (60°C).     

Fourier-transform surface-enhanced Raman scattering study on thiourea and some substituted thioureas adsorbed on chemically deposited silver films

Adsorption of thiourea, N,N′-diphenylthiourea (DIPTU), N-ethyl-N′-phenylthiourea (ETPTU) and N-(p-nitrophenyl)thiourea (NPTU), from acidic and neutral solutions, on chemically deposited silver film substrates are investigated using Fourier transform surface-enhanced Raman scattering (FT-SERS) technique. A strong band in the low frequency region, around 230 cm⁻¹ in the FT-SERS spectra of all these systems, assigned to Ag–S stretch, indicates a preferential adsorption through the sulfur atom. The frequencies and bandwidths of benzene ring vibrational modes in ETPTU as well as DIPTU are almost unaffected by adsorption indicating that benzene rings do not interact directly with the silver surface. A cis-cis conformation (both imino H-atoms cis with respect to thione sulfur atom) is proposed for DIPTU and ETPTU on the silver surface. In the case of NPTU, an additional interaction through the benzene ring is also observed as shown by the frequency shifts and band broadening of some benzene ring modes and weak intensity of the C–H stretching band.     

Some substituted thiourea complexes of molybdenum carbonyl

Preparation of monosubstituted thiourea complexes of molybdenum carbonyl [Mo(CO)₅L] both by thermal and UV irradiation methods have been described. The ligands (L) used were N,N′-dimethylthiourea (DMTU), N,N′-diphenylthiourea (DPTU), tetramethylthiourea (TMTU) and tetraethylthiourea (TETU). The complexes [Mo(CO)₅(L)] were characterised by NMR, IR, UV-visible and elemental analyses.     

Chemistry of the phenylglyoxal-p-diethylaminoanil and/or thiourea substituted ammine complexes

Summary Mixed ligand complexes of chromium(III), cobalt(II), cobalt(III), copper(II) and zinc(II) involving either the phenylglyoxal-p-diethylaminoanil and/or thiourea, and ammonia have been obtained by the partial or complete replacement of the strongly coordinated ammonia of ammine complexes. All the products were characterized by elemental analysis, molar conductance, magnetic susceptibility and i.r. and electronic spectral measurements for their bonding and structures.     

Effect of thiourea and substituted thioureas on dynein ATPase and on the turbidity response of Tetrahymena cilia.

The effects of thiourea and of several substituted thioureas -- phenylthiourea, alpha-naphtylthiourea, metiamide, and burimamide -- on dynein ATPase have been studied. The substituted thioureas are over 30 times more potent than thiourea in causing enhancement of 30S dynein ATPase activity and inhibition of 14S dynein ATPase activity. The effects of thiourea and phenylthiourea can be prevented by very low concentrations of beta-mercaptoethanol or dithiothreitol. Axonemal ATPase is also enhanced by the thioureas, but the reaction proceeds more slowly than for solubilized 30S dynein. Enhancement of 30S dynein ATPase by metiamide is prevented by low (approximately 1 microM) concentrations of ATP and, less effectively, by AMP-PNP, but not by AMP-PCP even though the latter is a stronger inhibitor of 30S dynein ATPase than is AMP-PNP. The thioureas inhibit the ATP-induced decrease in turbidity (measured as delta A350) of axonemal suspensions. Inhibition of the turbidity response is also prevented by low concentrations of beta-mercaptoethanol, but, in contrast to the irreversible enhancement of ATPase activity, inhibition of the turbidity response is largely reversible. The ability of 30S dynein to rebind onto twice-extracted axonemes is not changed by treatment with phenylthiourea or metiamide. These observations indicate that the thioureas react with at least two sets of SH or S--S groups on axonemes. Reaction with the group(s) on the 30S dynein causes an apparently irreversible enhancement of ATPase activity. Reaction with another group(s) causes a reversible inhibition of the turbidity response.     

Potentiometric study of silver complexes with thiourea in acid media

Formation of silver complexes with thiourea in three different acids (perchloric, methanesulfonic, and sulfamic) was studied potentiometrically using modified Leden's method. It was established that, under conditions similar to the ones used for commercial electroplating of silver alloys, silver and thiourea form predominantly binuclear complexes Ag₂tu _n (n =?1–6). Calculated complex stability constants were similar in all cases suggesting that the acidity and the type of anion have little effect on the structure.     

Kinetics and mechanism of thermal decomposition of cadmium(II) complexes with substituted thioureas

From the thermal decomposition curves of cadmium(II) complexes with substituted thioureas (methyl-, dimethyl-, ethyl-, diethyl-, butyl-, dibutyl-, phenyl-, diphenyl-, acetyl- and benzoylphenylthiourea), the kinetic parameters of the thermal decompositions of these complexes were determined and a decomposition mechanism was suggested. The following thermal stability sequence is given for the Cd(II) complexes: complexes with alkylthioureas < complexes with phenylthioureas < complexes with acylthioureas.

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Zusammenfassung Die kinetischen Parameter der thermischen Zersetzung von Verbindungen der Formeln Cd(MeTM)₄(ClO₄)₂, Cd(DMeTM)₄(ClO₄)₂, Cd(EtTM)₄(ClO₄)₂, Cd(DEtTM)₄(ClO₄)₂, Cd(BuTM)₄(CtO₄)₂, Cd(DBuTM)₄(ClO₄)₂, Cd(AcTM)₃(ClO₄)₄, Cd(FTM)₄(ClO₄)₂ und Cd(DFTM)₄(ClO₄)₂ wurden mittels TG and DTG untersucht. Die Reaktionsordnung (n) und die Aktivierungsenergie (E _a) wurden nach der graphischen Methode ermittelt.

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Synthesis and characterization of tungsten carbonyl complexes containing N-methyl substituted urea and thiourea ligands

Six new mixed-ligand tungsten carbonyl complexes containing N-methyl substituted urea and thiourea of the type W(CO)₄[RCH₂N-(C=X)NH₂] where X?=?O or S and R?=?morpholine, piperidine and diphenylamine are reported. These have been prepared by refluxing hexacarbonyl tungsten(0) with corresponding ligands in THF to produce cis-disubstituted products, [(L-L)W(CO)₄] where L-L?=?a chelating bidentate ligand, morpholinomethyl urea (MMU), morpholinomethyl thiourea (MMTU), piperidinomethyl urea (PMU), piperidinomethyl thiourea (PMTU), diphenylaminomethyl urea (DAMU) and diphenylaminomethyl thiourea (DAMTU). The compounds have been characterized by elemental analysis, IR, electronic and ¹³C NMR spectra, magnetic moments and conductivity measurements. The IR spectra suggests that in all the complexes, the ligands are bidentate chelating, coordinating the metal through carbonyl oxygen or thiocarbonyl sulphur and the ring nitrogen or tert-nitrogen of diphenylamine. The CO force constants and CO–CO interaction constants for these derivatives have also been calculated using Cotton–Kraihanzel secular equations, which indicate poor π-bonding ability of the ligands. ¹³C NMR and electronic spectra reveal loss of cis-carbonyl ligands to produce cis-disubstituted tetracarbonyl derivatives. Molecular modeling studies have been carried out using Hyperchem release 7.52 which suggest a distorted octahedral geometry for these complexes.     

An iodide/anion exchange route to benzimidazolylidene silver complexes from benzimidazolium iodide: Crystal structures of N,N′-dibutylbenzimidazolylidene silver chloride, bromide, cyanide and nitrate

Syntheses of N,N′-dibutylbenzimidazolylidene silver complexes having chloride, nitrate or cyanide as an anion part through an iodide/anion exchange from N,N′-dibutylbenzimidazolium iodide are described, representing a practical route to benzimidazolylidene silver complexes from readily accessible benzimidazolium iodide. The crystal structures of N,N′-dibutylbenzimidazolylidene silver chloride, bromide, cyanide and nitrate have been determined, showing a close ligand-unsupported Ag-Ag interaction in [(NHC)₂]Ag⁺[AgX₂]⁻ and a “T” shape geometry about the silver(I) cation in complexes of chloride, bromide and cyanide, but a nearly linear shape in the bis(N,N′-dibutylbenzimidazolylidene) silver complex [ with non-coordinating nitrate anion.     

Synthesis of some pyridyl substituted ureas and thioureas

Thirty five pyridyl-substituted ureas and thioureas were synthesized in order to study the relationship between chemical structure and biological activity. These compounds were obtained by the reaction of pyridylamines with isocyanates and isothiocyanates, as well as by the desulfurization of the corresponding thioureas. When tested, all these compounds exhibited weak physiological activity.     

Substituent effects on the structures of silver complexes with monoazatrithia-12-crown-4 ethers bearing substituted aromatic rings

New 4'-methoxybenzyl-, 4'-methylbenzyl-, benzyl-, 3',5'-difluorobenzyl-, 3',5'-dichlorobenzyl-, and 4'-nitrobenzyl-armed monoazatrithia-12-crown-4 ethers were prepared by the reductive amination of monoazatrithia-12-crown-4 with the appropriate benzenecarbaldehyde in the presence of NaBH(OAc)3. Cold electrospray ionization mass spectrometry and X-ray crystallography show that silver complexes with armed monoazatrithia-12-crown-4 ethers bearing aromatic side arms with electron-donating groups or electron-withdrawing groups are coordination polymers and trimers, respectively. The structures of the silver complexes were strongly dependent on the strength of the CH...pi interactions, which are controlled by substituent effects on the aromatic side arms.     

Crystal structures of N,N'-(m-tolyl)thiourea and N,N'-(p-tolyl)thiourea.

C15H16N2S is monoclinic [orthorhombic], P2(1)/c [Pbcn]. Unit-cell dimensions at 293 K are a = 9.506(1), b = 7.629(1), c = 20.077(1)A, beta = 99.93(1) degrees, V= 1434.2(2)A(3), D(x) = 1.187 g/cm3, and Z = 4 [a = 11.806(2), b = 13.954(2), c = 8.466(1)A, V = 1394.7(3)A(3), D(x) = 1.221 g/cm3, and Z = 8]. The R value is 0.049 [0.045] for 1620 [1229] observed reflections. The dihedral angle between the tolyl rings is 53.6(1) degrees [47.9(1)degrees]. The crystal structures are stabilized by N-H...S hydrogen bonds and van der Waals forces.     

Crystal structures of cyclodextrin complexes with chiral molecules

The chiral recognition by cyclodextrins and permethylated cyclodextrins have been investigated on the basis of the X-ray data of crystalline inclusion complexes. The macrocyclic ring of - and -cyclodextrin shows a round and symmetrical structure. -Cyclodextrin includes racemic 1-phenylethanol with the statistical disorder of the hydroxyl group. A pair of the R- and S-isomers of flurbiprofen are included within the cylindrical cavity formed by dimeric -cyclodextrin molecules with a head-to-head arrangement. The macrocyclic ring of permethylated cyclodextrins is remarkably distorted from the regular polygonal symmetry and has more flexibility in the conformational change than cyclodextrins. Owing to the distorted conformation and steric hindrance involving methyl groups, permethylated cyclodextrins do not equally include both isomers, as demonstrated by the permethylated -cyclodextrin complexes with mandelic acids. Permethylated -cyclodextrin binds D-mandelic acid more tightlyvia a host-guest hydrogen bond and induced-fit conformational change. Permethylated -cyclodextrin forms a hydrated crystalline complex with R-flurbiprofen, but S-flurbiprofen forms a non-hydrated crystalline complex. Significant differences between the two complexes are found in the orientation of the phenyl group and hydrogen-bond formation involving the carboxyl group.     

Colorimetric detection of cyanide with phenyl thiourea derivatives

Three structurally simple thiourea derivatives 1-3 were prepared, and their chromogenic behaviors toward various anions were investigated in aqueous solution. Among them 1 showed good sensitivity and selectivity for cyanide ion and also can distinguish it from other anions by different color changes. Besides that, the receptor 1 has a sensitive detection limit (1.27 μM) for cyanide ion accordingly it can be used as a colorimetric sensor for the determination of cyanide ion. The use of the test strip of sensor 1 to detect cyanide ion was also reported.     

NMR studies of thioureas and their zinc complexes

The NMR spectra of thiourea, a number of N substituted thioureas and of the zinc(II) complexes of these ligands are reported. Two rate processes occur. The first arises from rotation about the CN bond of the thiourea and requires activation energies in the range of 7–12 kcal/mole for the free ligands. The activation energy for rotation in the complexed ligand is substantially higher. The second rate process involves ligand exchange. The rate for this process is slightly greater than that for analogous Co(II) and Ni(II) compounds. Approximate enthalphies and entropies of activation are reported.     

Crystal structures and molecular modeling of 1,8 chalcogenide‐substituted naphthalenes

The molecular structures of naphtho[1,8‐cd][1,2]dithiole, naphtho[1,8‐cd][1,2]diselenole, naphtho[1,8‐cd][1,2]ditellurole, naphtho[1,8‐cd]‐ [1,2]dithiole 1‐oxide, naphtho[1,8‐cd][1,2]dithiole 1,1‐dioxide, and naphtho[1,8‐cd][1,2]dithiole 1,1,2‐trioxideand naphtho[1,8‐cd][1,2]dithiole 1,1,2,2‐tetroxide are compared. The E–E distance varies, broadly reflecting the degree of distortion imposed by the rigid naphthalene backbone as well as the degree of oxidation at sulfur. Index Entry: The naphthalene backbone imposes shortening of E–E bond lengths when E = S and Se compared to Ph E E Ph systems but is itself subject to distortion as a consequence of the steric bulk of the E atoms. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:530–542, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20055     

Crystal structures of copper(II) complexes of 2-formylpyridine substituted thiosemicarbazones; the first example of a coordinated thiosemicarbazone with a thiol function

The crystal structures of two 5-coordinate copper(II) complexes containing neutral, tridentate 2-formylpyridine N(4)-substituted thiosemicarbazones have been determined. 2-Formylpyridine N(4)-cyclohexylthiosemicarbazone, HFo4CHex coordinates via the pyridine nitrogen, imine nitrogen and thione sulfur with two chloro ligands to produce [Cu(HFo4CHex)Cl₂]. Similarly, 2-formylpyridine 3-(4-methylpiperazine)thiosemicarbazone, HFoppz4M, produces [Cu(HFoppz4M)Cl₂] with one major difference; rather than the expected thione form of the thiosemicarbazone moiety, it coordinates as the thiol isomer. Both complexes are close to a square pyramid structure with axial and equatorial chloro ligands and the thiosemicarbazone moieties of both ligands nearly planar. Also included is the crystal structure of N-cyclohexylthiosemicarbazide, CHextsc.     

Cyclization of substituted 1,3-alkenynes with thiourea

2-Mercapto-4-methylpyrimidine was obtained by the reaction of 1,3-butenyne ethers, thioethers, and amines with thiourea. The corresponding 2-mercapto-4-alkylpyrimidines were obtained for the first time by analogous cyclization of 1-methoxy-1-buten-3-yne homologs (CH₃OCH=CHC=CR, where R=CH₃, C₂H₅, and C₃H₇) with thiourea. The effect of the nature of the substituents in the 1,3-enyne system on the capacity for cyclization with thiourea was investigated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 843–845, June, 1971.