1H, 13C, 15N NMR and IR Spectroscopic Studies of a Rh(II) Complex of Thiourea

A rhodium(II) complex of thiourea (Tu), Rh₂(OAc)₄Tu₂, has been prepared from Rh₂(OAc)₄(H₂O)₂ and characterized. A shift of the ν(N?H) vibration towards higher frequencies in the IR spectrum is consistent with sulfur coordination to rhodium(II). ¹³C NMR spectra recorded in DMSO-d ₆ reveal that thiourea is replaced by DMSO-d ₆ solvent, followed by replacement of acetate ions by free thiourea. ¹⁵N NMR indicates some nitrogen involvement in coordination to form an S?N chelate.     

The investigation on the relative stability of different clusters of thiourea dioxide in water using gas phase quantum chemical calculations

The relative stability of different clusters of thiourea dioxide (TDO) in water is examined using gas phase quantum chemical calculations at the MP2 and B3LYP level with 6‐311++G(d,p) basis set. The possible equilibrium structures and other energetic and geometrical data of the thiourea dioxide clusters, TDO‐(H₂O)_n (n is the number of water molecules), are obtained. The calculation results show that a strong interaction exists between thiourea dioxide and water molecules, as indicated by the binding energies of the TDO clusters progressively increased by adding water molecules. PCM model is used to investigate solvent effect of TDO. We obtained a negative hydration energy of ?20.6 kcal mol^?1 and free‐energy change of ?21.0 kcal mol^?1 in hydration process. On the basis of increasing binding energies with adding water molecules and a negative hydration energy by PCM calculation, we conclude thiourea dioxide can dissolve in water molecules. Furthermore, the increases of the C? S bond distance by the addition of water molecules show that the strength of the C? S bonds is attenuated. We find that when the number of water molecules was up to 5, the C? S bonds of the clusters, TDO‐(H₂O)₅ and TDO‐(H₂O)₆ were ruptured. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009     

Influence of the Homopolar Dihydrogen Bonding CH⋅⋅⋅HC on Coordination Geometry: Experimental and Theoretical Studies

The reaction of the N‐thiophosphorylated thiourea (HOCH₂)(Me)₂CNHC(S)NHP(S)(OiPr)₂ (HL), deprotonated by the thiophosphorylamide group, with NiCl₂ leads to green needles of the pseudotetrahedral complex [Ni(L‐1,5‐S,S′)₂] ? 0.5 (n‐C₆H₁₄) or pale green blocks of the trans square‐planar complex trans‐[Ni(L‐1,5‐S,S′)₂]. The former complex is stabilized by homopolar dihydrogen C?H???H?C interactions formed by n‐hexane solvent molecules with the [Ni(L‐1,5‐S,S′)₂] unit. Furthermore, the dispersion‐dominated C?H??? H?C interactions are, together with other noncovalent interactions (C?H???N, C?H???Ni, C?H???S), responsible for pseudotetrahedral coordination around the Ni^II center in [Ni(L ‐1,5‐S,S′)₂] ? 0.5 (n‐C₆H₁₄).     

Structural studies and biological activity evaluation of Pd(II), Pt(II) and Ru(II) complexes containing N‐phenyl,N`‐(3‐triazolyl)thiourea

[MCl(H₂L)(OH₂)]·1.5H₂O (M = Pd(II) ( 1 ) and Pt(II) ( 2 )) and [Ru(H₂L)₂(OH₂)₂]·3H₂O ( 3 ) (H₃L: N‐phenyl, N`‐(3‐triazolyl)thiourea) were synthesized, characterized and tested for their antibacterial activities against Staphylococcus aureus and Escherichia coli bacteria. The thiourea derivative is coordinated to Mⁿ⁺ ions as a mono‐negatively N,S‐bidentate ligand via the enolization of C = S group and triazole N center. The density functional theory calculations reveal that presence of a water molecule in a trans position to triazole ring increased the stability of d⁸ metal ions complexes via the formation of strong Cl…NH intramolecular H‐bond. The cis‐Ru(II)‐isomer with two isoenergetically H₂L^? molecules are more stable than the trans‐analog. Coordination of H₃L to Ru(II) ion did not alter the toxicity of the free ligand, while the interaction with the d⁸ metal ions gave rise to inactive compounds.     

Quantum chemistry investigation of electronic structure and NMR spectral characteristics for fluorides of dialkylamidosulfoxylic acids and related compounds

The parent (H₂N? S? F) and N,N‐dialkyl‐substituted fluorides of amidosulfoxylic acid (R₂N? S? F, R?Me or R₂N?Morph) as well as the related compounds X? S? F (X?CH₃, OH, F, SiH₃, PH₂, SH, Cl) have been investigated with quantum chemical calculations at the ab initio (MP2) level of approximation. The geometries, electronic structures, molecular orbital (MO) energies and NMR chemical shift values have been calculated to evaluate the role and extent of the polarization and delocalization effects in forming of the high‐field fluorine NMR resonances within the series of interest. The δF magnitudes for all investigated fluorides of amidosulfoxylic acid as well as the δN value calculated for Me₂N? S? F are in the good agreement with the ¹⁹F and ¹⁴N NMR chemical shift values measured experimentally. For the parent compounds, H₂N? S? F and H₂N? SO₂? F, the orientation of principal axes of the magnetic shielding tensors and the corresponding principal σ_ii values along these axes have been qualitatively interpreted basing on the analysis of the MO interactions in the presence of the rotating magnetic field. Copyright © 2009 John Wiley & Sons, Ltd.     

Hydrogen bond and σ‐hole interaction in M2C=S···HCN (M = H,F, Cl,Br, HO,H3C,H2N) complex: Dual roles of C=S group and substitution effect

An ab initio computational study of the dual functions of C?S group in the M₂C?S ··· HCN (M = H, F, Cl, Br, HO, H₃C, H₂N) complex has been performed at the MP2(Full)/aug‐cc‐pVTZ level. The C?S group can act as both the electron donor and acceptor, thus two minima complexes were found for each molecular pairs. The interaction energy of hydrogen bond in the F, Cl, or Br substituted complexes is less negative than that in the corresponding H₂CS one, while the interaction energy of the σ‐hole interaction is more negative. The OH substitution weakens the hydrogen bond, whereas the H₃C and H₂N substitution strengthens it. The σ‐hole interaction in the HO, H₃C, and H₂N complexes is very weak. The substitution effect has been understood with electrostatic induction and conjugation effects. The energy decomposition analysis has been performed for the halogen‐substituted complexes. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012.     

Phase Evolution of Cu?S System in Ethylene Glycol Solution: the Effect of Anion and PVP on the Transformation of Thiourea

The transformation mechanisms of thiourea in ethylene glycol solution was systematically investigated in this report, which shows the transformation process is influenced by the anion (NO^3?, Cl^?, Br^?) and polyvinylpyrrolidone (PVP). Thiourea (tu) isomerizes into ammonium thiocyanate when NO^3? is present, regardless of the existence of PVP. For Cl^?, thiourea coordinates with copper anion to form [Cu(tu)]Cl·1/2H₂O complex whether PVP is present. When it comes to Br^?, thiourea hydrolyzes in the cooperation of PVP or coordinates with copper anion to form [Cu(tu)Br]·1/2H₂O complex without PVP. The different transformation routes will lead to different phase evolution of the Cu? S system. This work may provide a new understanding of the transformation of thiourea in ethylene glycol solution. The optical properties of the as‐prepared copper sulfides exhibit signi?cant stoichiometry‐dependent features which may have potential applications in semiconductor photovoltaic devices.     

Crystallographic study of self‐organization in the solid state including quasi‐aromatic pseudo‐ring stacking interactions in 1‐benzoyl‐3‐(3,4‐dimethoxyphenyl)thiourea and 1‐benzoyl‐3‐(2‐hydroxypropyl)thiourea

1‐Benzoylthioureas contain both carbonyl and thiocarbonyl functional groups and are of interest for their biological activity, metal coordination ability and involvement in hydrogen‐bond formation. Two novel 1‐benzoylthiourea derivatives, namely 1‐benzoyl‐3‐(3,4‐dimethoxyphenyl)thiourea, C₁₆H₁₆N₂O₃S, (I), and 1‐benzoyl‐3‐(2‐hydroxypropyl)thiourea, C₁₁H₁₄N₂O₂S, (II), have been synthesized and characterized. Compound (I) crystallizes in the space group P , while (II) crystallizes in the space group P 2₁/c . In both structures, intramolecular N—H…O hydrogen bonding is present. The resulting six‐membered pseudo‐rings are quasi‐aromatic and, in each case, interact with phenyl rings via stacking‐type interactions. C—H…O, C—H…S and C—H…π interactions are also present. In (I), there is one molecule in the asymmetric unit. Pairs of molecules are connected via two intermolecular N—H…S hydrogen bonds, forming centrosymmetric dimers. In (II), there are two symmetry‐independent molecules that differ mainly in the relative orientations of the phenyl rings with respect to the thiourea cores. Additional strong hydrogen‐bond donor and acceptor –OH groups participate in the formation of intermolecular N—H…O and O—H…S hydrogen bonds that join molecules into chains extending in the [001] direction.     

Über Chalkogenolate. 123. Untersuchungen über N-Cyanomonothiocarbimidsäure. 3. O,S-Dimethylester der N-Cyanomonothiocarbimidsäure. Thiolyse und Hydrolyse des Esters

On Chalcogenolates. 123. Studies on N-Cyanomonothiocarbimic Acid. 3. O, S-Dimethyl Ester of N-Cyanomonothiocarbimic Acid. Thiolysis and Hydrolysis of this Ester (H₃CO)(H₃CS)C?N? CN has been prepared by reaction of K₂[SOC?N? CN] · H₂O with H₃CI. The thiolysis of this ester gives (H₃CO)(H₃CS)C?N? CS? NH₂. The acid hydrolysis forms (H₃CO)(H₃CS)C?N? CO? NH₂ via [(H₃CO)(H₃CS)C?N? C?NH]Cl. All compounds have been characterized by diverse methods.     

A Combined Experimental and Theoretical Electron Density Study of Intra‐ and Intermolecular Interactions in Thiourea S,S‐Dioxide

The thiourea S,S‐dioxide molecule is recognized as a zwitterion with a high dipole moment and an unusually long C? S bond. The molecule has a most interesting set of intermolecular interactions in the crystalline state—a relatively strong O???H? N hydrogen bond and very weak intermolecular C???S and N???O interactions. The molecule has C_s symmetry, and each oxygen atom is hydrogen‐bonded to two hydrogen atoms with O???H? N distances of 2.837 and 2.826 Å and angles of 176.61 and 158.38°. The electron density distribution is obtained both from Xray diffraction data at 110 K and from a periodic density functional theory (DFT) calculation. Bond characterization is made in terms of the analysis of topological properties. The covalent characters of the C? N, N? H, C? S, and S? O bonds are apparent, and the agreement on the topological properties between experiment and theory is adequate. The features of the Laplacian distributions, bond paths, and atomic domains are comparable. In a systematic approach, DFT calculations are performed based on a monomer, a dimer, a heptamer, and a crystal to see the effect on the electron density distribution due to the intermolecular interactions. The dipole moment of the molecule is enhanced in the solid state. The typical values of ρ_b and H_b of the hydrogen bonds and weak intermolecular C???S and N???O interactions are given. All the interactions are verified by the location of the bond critical point and its associated topological properties. The isovalue surface of Laplacian charge density and the detailed atomic graph around each atomic site reveal the shape of the valence‐shell charge concentration and provide a reasonable interpretation of the bonding of each atom.     

Über Chalkogenolate. 122. Untersuchungen über N-Cyanomonothiocarbimidsäure 2. Kalium-S-methyl-N-cyanomonothiocarbimat und S-Methyl-N-cyanomonothiocarbimidsäure

On Chalcogenolates. 122. Studies on N-Cyanomonothiocarbimic Acid. 2. Potassium S-Methyl N-Cyanomonothiocarbimate and S-Methyl N-Cyanomonothiocarbimic Acid The reaction of K₂[SOC?N? CN] · H₂O with H₃CI gives K[O(H₃CS)C?N? CN]. The potassium salt reacts with acid to form (HO)(H₃CS)C?N? CN and with H₃CO? CO? Cl to yield (H₃CO? CO? O)(H₃CS)C?N? CN. The compounds have been characterized by means of spectroscopic methods.     

Palladium(II) complexes with 1-allyl-3-(2-pyridyl)thiourea: Synthesis and spectroscopic characterization

New Pd(II) complexes with 1-allyl-3-(2-pyridyl)thiourea (APTU) of the formulas [Pd(C₉H₁₁N₃S)Cl₂] (I) and [Pd(C₉H₁₁N₃S)₂]Cl₂ (II) were obtained and examined by UV-Vis, IR, and 1H NMR spectroscopy. The conditions for the complexation reactions were optimized. The instability constants and molar absorption coefficients of these complexes were calculated. Comparison of the characteristic bands in the UV-Vis and IR spectra of the complexes and free APTU revealed that the ligand in both complexes is coordinated to the metal atom in the thione form in the bidentate chelating mode through the S atom of the thiourea group and the pyridine N atom. In the UV-Vis spectra of the complexes, the charge transfer bands (π → π* Py) and n → π* (C=N_Py), (C=S) experience hypsochromic shifts by 450–470 cm⁻¹ caused by the coordination of APTU to the metal ion, which gives rise to ligand-metal charge-transfer bands (C=N_Py → Pd, n → π* (C=S)) and (SPd). The protons in the 6-, 4-, and 3-positions of the pyridine ring and the thiourea NH proton in the chelate ring are most sensitive to the complexation.     

Diacetatobis­(tri­methyl­ene­thio­urea)­zinc(II) monohydrate

In the title compound, [Zn(CH₃COO)₂(C₄H₈N₂S)₂]·H₂O, the Zn atom is tetrahedrally coordinated in the ZnO₂S₂ form. N—H?O and O—H?O intramolecular and intermolecular hydrogen bonds are formed by the four N atoms and the water mol­ecule. N—H?O intermolecular hydrogen bonds and C—H?S and C—H?O intermolecular interactions interconnect columns formed by the mol­ecules into layers. Adjacent layers are then linked by other N—H?O and O—H?O intermolecular hydrogen bonds to form a three‐dimensional framework throughout the structure. The orientations of the acetate planes are such that the Zn atom lies within them.     

Adsorption of small molecules on helical gold nanorods: A relativistic density functional study

We study the adsorption of a variety of small molecules on helical gold nanorods using relativistic density functional theory. We focus on Au₄₀ which consists of a central linear strand of five gold atoms with seven helical strands of five gold atoms on a coaxial tube. All molecules preferentially adsorb at a single low‐coordinated gold atom on the coaxial tube at an end of Au₄₀. In most cases, there is significant charge transfer (CT) between Au₄₀ and the adsorbate, for CO and NO₂, there is CT from the Au₄₀ to adsorbate while for all other molecules there is CT from the adsorbate to Au₄₀. Thus, Au₄₀‐adsorbate can be described as a donor–accepter complex and we use charge decomposition analysis to better understand the adsorption process. We determine the adsorption energy order to be C₅H₅N >NO₂ > CO > NH₃ > CH₂?CH₂ > CH₂?CH? CHO > NO > HC?CH > H₂S > SO₂ > HCN > CH₃OH > H₂C?O > O₂ > H₂O > CH₄ > N₂. We find that the Au? C, Au? N, Au? S, and Au? O bonds are surprisingly strong, with clear implications for reactivity enhancement of the adsorbate. The Au? H bond is relatively weak but, for interactions via an H atom that is bonded to a carbon atom (e.g., CH₄), we find that there is large charge polarization of the Au? H? C moiety and partial activation of the inert C? H bond. Although the Au? S and Au? O bonds are generally weaker than the Au? C and Au? N bonds, we find that adsorption of H₂S or H₂O causes greater distortion of Au₄₀ in the binding region. However, the degree of distortion is small and the helical structure is retained, demonstrating the stability of the helical Au₄₀ nanorod under perturbations. © 2014 Wiley Periodicals, Inc.     

Über Chalkogenolate. 114. Kristallstruktur von Kalium-N-cyanodithiocarbimat-Monohydrat K2[S2CN ? CN] · H2O

On Chalcogenolates. 114. Crystal Structure of Potassium N-Cyanodithiocarbimate Monohydrate K₂[S₂C?N ? CN] · H₂O The crystal structure of the title compound has been determined and refined to R = 0.0287. K₂[S₂C?N ? CN] · H₂O crystallizes in the orthorhombic space group Pnma with a = 10.336(1) Å, b = 7.862(1) Å, c = 9.882(1) Å Z = 4. The structure is built up from layers of cations and anions. The potassium ion is coordinated by O, N, S atoms. The coordination polyhedron is a quadratic antiprism. ¹³C and ¹⁵N NMR data are reported and discussed.     

Intrinsic Acid–Base Properties of a Hexa‐2′‐deoxynucleoside Pentaphosphate,d(ApGpGpCpCpT): Neighboring Effects and Isomeric Equilibria

The intrinsic acid‐base properties of the hexa‐2′‐deoxynucleoside pentaphosphate, d(ApGpGpCpCpT) [=(A1?G2?G3?C4?C5?T6)=(HNPP)^5?] have been determined by ¹H NMR shift experiments. The pK_a values of the individual sites of the adenosine (A), guanosine (G), cytidine (C), and thymidine (T) residues were measured in water under single‐strand conditions (i.e., 10 % D₂O, 47 °C, I=0.1 M , NaClO₄). These results quantify the release of H⁺ from the two (N7)H⁺ (G?G), the two (N3)H⁺ (C?C), and the (N1)H⁺ (A) units, as well as from the two (N1)H (G?G) and the (N3)H (T) sites. Based on measurements with 2′‐deoxynucleosides at 25 °C and 47 °C, they were transferred to pK_a values valid in water at 25 °C and I=0.1 M . Intramolecular stacks between the nucleobases A1 and G2 as well as most likely also between G2 and G3 are formed. For HNPP three pK_a clusters occur, that is those encompassing the pK_a values of 2.44, 2.97, and 3.71 of G2(N7)H⁺, G3(N7)H⁺, and A1(N1)H⁺, respectively, with overlapping buffer regions. The tautomer populations were estimated, giving for the release of a single proton from five‐fold protonated H₅(HNPP)^±, the tautomers (G2)N7, (G3)N7, and (A1)N1 with formation degrees of about 74, 22, and 4 %, respectively. Tautomer distributions reveal pathways for proton‐donating as well as for proton‐accepting reactions both being expected to be fast and to occur practically at no “cost”. The eight pK_a values for H₅(HNPP)^± are compared with data for nucleosides and nucleotides, revealing that the nucleoside residues are in part affected very differently by their neighbors. In addition, the intrinsic acidity constants for the RNA derivative r(A1?G2?G3? C4?C5?U6), where U=uridine, were calculated. Finally, the effect of metal ions on the pK_a values of nucleobase sites is briefly discussed because in this way deprotonation reactions can easily be shifted to the physiological pH range.     

Kinetics and mechanism of the oxidation of 4‐methyl‐3‐thiosemicarbazide by acidic bromate

The oxidation of 4‐methyl‐3‐thiosemicarbazide (MTSC) by bromate and bromine was studied in acidic medium. The stoichiometry of the reaction is extremely complex, and is dependent on the ratio of the initial concentrations of the oxidant to reductant. In excess MTSC and after prolonged standing, the stoichiometry was determined to be H₃CN(H)CSN(H)NH₂ + 3BrO₃^? → 2CO₂ + NH₄⁺ + SO₄^2? + N₂ + 3Br^? + H⁺ (A). An interim stoichiometry is also obtained in which one of the CO₂ molecules is replaced by HCOOH with an overall stoichiometry of 3H₃CN(H)CSN(H)NH₂ + 8BrO₃^? → CO₂ + NH₄⁺ + SO₄^2? + HCOOH + N₂ + 3Br^? + 3H⁺ (B). Stoichiometry A and B are not very different, and so mixtures of the two were obtained. Compared to other oxidations of thiourea‐based compounds, this reaction is moderately fast and is first order in both bromate and substrate. It is autocatalytic in HOBr. The reaction is characterized by an autocatalytic sigmoidal decay in the consumption of MTSC, while in excess bromate conditions the reaction shows an induction period before autocatalytic formation of bromine. In both cases, oxybromine chemistry, which involves the initial formation of the reactive species HOBr and Br₂, is dominant. The reactions of MTSC with both HOBr and Br₂ are fast, and so the overall rate of oxidation is dependent upon the rates of formation of these reactive species from bromate. Our proposed mechanism involves the initial cleavage of the C? N bond on the azo‐side of the molecule to release nitrogen and an activated sulfur species that quickly and rapidly rearranges to give a series of thiourea acids. These thiourea acids are then oxidized to the sulfonic acid before cleavage of the C? S bond to give SO₄^2?, CO₂, and NH₄⁺. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 237–247, 2002     

1‐(Diaminomethylene)thiourea: a tautomer of 2‐imino‐4‐thiobiuret

Crystals of the title compound, C₂H₆N₄S, are built up from nonplanar 1‐(diaminomethylene)thiourea molecules. Pairs of molecules related by inversion are linked by N—H...N hydrogen bonds to form dimeric units, and weak N—H...S interactions link these dimeric units into a three‐dimensional framework.     

A 1:1 molecular complex of bis(4‐aminophenyl) disulfide and 4‐aminothiophenol

The centrosymmetric crystal structure of the title complex, C₁₂H₁₂N₂S₂·C₆H₇NS, is built up of dimers of the constituent mol­ecules and stabilized by a herring‐bone geometry between the phenyl rings. The structure reveals an N—H?N—H?N—H?S co‐operative hydrogen‐bonded chain, and C—H?S and N—H?π hydrogen bonds. The S—H group forms an uncommon S—H?π interaction.