Spectral Studies of Palladium(II)-Allyl Thiourea System

Abstract

Palladium(II) forms 1:1 and 1:4 complexes with allyl thiourea. The molar composition of the complexes was determined by molar-ratio and continuous variation methods and confirmed by means of elemental analysis of the compounds isolated from solution.

Conformity to Beer's law was observed for up to 12 μg ml^?1 of 4 palladium in strongly acidic medium (molar absorptivity 2.28×10⁴ 1 mol^?1 cm^?1 at 292 nm);the Sandell's sensitivity of the reaction for palladium is 0.0047 μg cm^?2 per 0.001 absorbance unit.

The tolerance of the system to platinum metals and other common cations is satisfactory.

A statistical evaluation of the analytical procedure of palladium determination has been undertaken.

The infrared spectra of allyl thiourea and of its 1:1 and 1:4 palladium complexes have been measured in the 2.5–50μ region. The absorption bands have been assigned. The spectra reveal that allyl thiourea forms sulphur-to-metal bonds only, rather than nitrogen-to-metal bonds in the complexes studied.     

Surface chemistry and colloids: International Review of Science,Physical Chemistry Series Two,Vol. 7, edited by M. Kerker,consultant editor A. D. Buckingham,Butterworths, London and Boston, 1975, pp. 269, price £13.45

Infrared and Raman spectra of pentachlorophenol and pentachlorothiophenol have been measured and the fundamental frequencies assigned. The two-fold barrier to rotation of the —OH group in the former compound is found to be 2190 cm^?1 (26.4 kJ mol^?1)     

Effect of stabilizers in the thermal treatment of PVC—X. An i.r. spectroscopic study of PVC with basic cadmium stearate

Infrared spectra (1900-1470 cm^?1) were studied for PVC films stabilized with basic Cd stearate and its mixture with stearic acid, after thermal degradation at 180° in air. Infrared spectroscopy makes it possible to follow the formation of Cd chloride-stearate on the basis of an absorption band at 1560–1565 cm^?1. The spectral data are compared with a potentiometric determination of HCl released from the mixture.     

The infrared vibration—rotation spectrum of trans and cis nitrous acid

Infrared spectra of the trans and the cis isomers of nitrous acid, both HONO and DONO, have been observed in the gas phase using a Fourier transform interferometer with a resolution of about 0.05 cm^?1 from 4000 to 500 cm^?1. Rotational analyses are reported on eleven of the fundamentals and some overtones.     

IR-photodissociation of size selected molecular clusters and their structures

Infrared photodissociation spectra of (CH₃NH₂) _n clusters were measured fromn=2 ton=6 near the monomer absorption of the C-N stretching mode at 1044 cm^?1 using a cw-CO₂ laser. The clusters were size-selected by scattering from a helium beam. The spectrum of cold dimers shows a red (1038 cm^?1) and a blue (1048 cm^?1) shifted peak which is attributed to the non-equivalent position of the C-N in the open dimer structure. The larger clusters exhibit only one peak between 1045.4 cm^?1 and 1046.0 cm^?1 caused by the equivalent position of the C-N in the cyclic structures of the larger clusters. Structure calculations confirm these results. Secondly, the mixed complexes C₂H₄-CH₃COCH₃ and C₂H₄-(CH₃COCH₃)₂ were investigated. The dimer spectrum, measured around the monomer frequency of the out-of-plane bending mode of C₂H₄ at 949 cm^?1, shows two peaks at 946.2 cm^?1 and 961.3 cm^?1. This splitting is attributed to two different isomers that are found in configuration calculations. A similar behaviour is found for the trimer.     

Spectral Investigation on Ruthenium(III)-allyl Thiourea System

Abstract

Ruthenium(III) forms a 1:2 complex with allyl thiourea. Conformity to Beer's law was observed for up to 12 pg/ml of ruthenium, in acidic medium.

The molar absorptivity of the complex is 1.66E+04 1 mol^?1 cm^?1, at 270 nm; the Sandell's sensitivity of the reaction for ruthenium is 0.0061 μg cm^?2 per 0.001 absorbance unit.

The tolerance to diverse ions is quite satisfactory.

The infrared spectra of allyl thiourea and of its ruthenium complex, recorded in the 2.5 - 50 μ region, reveal that only sulphur-to-ruthenium bonds are present in the complex.

A comparison with the main, most recent, spectrophotometric reagents for ruthenium is reported. The present method has the advantages of simplicity and reasonable sensitivity.     

Effect of stabilizers in the thermal treatment of PVC—VI. An I.R. spectroscopic study of the stabilization of PVC with Ba and Cd stearates

Infrared spectra (1800-1400 or 2200-1400 cm^?1) were studied for PVC films stabilized with Ba, Cd stearate and with their equimolar mixture, and previously subjected to thermal degradation at 180° in air, or in a few cases in nitrogen. At least two types of oxygen-containing products were formed during the degradation. The use of partly deuterated stearates showed that esterification of the PVC chain cannot be regarded as the predominant mechanism of stabilization. On the other hand, the presence of atmospheric oxygen leading to the formation of carbonyl groups on the chain seems to play an essential role in the degradation. Infrared spectroscopy makes it possible to follow the consumption of barium or cadmium stearates during thermal stress on the basis of a band assigned to the antisymmetrical stretching vibration of COO^? (1510 or 1550 cm^?1).     

Infrared spectra of FHF− in alkali halides

The bifluoride ion, FHF^?, has been substitutionally isolated within single crystal samples of several different alkali halides. Infrared spectra of these crystals have been studied for sample temperatures down to 8K when half-bandwidths of less than 1 cm^?1 have been observed. (Note that at room temperature ν₃ is observed to have a half-bandwidth of about 40 cm^?1). The frequency shifts and half-bandwidth changes caused by cooling are considered together with the frequency shifts caused by pressures up to 10 k bar.The low temperature spectra clearly indicate that FHF^? is a linear symmetrical ion when substitutionally isolated within alkali halides of either the NaCl or CsCl structure.     

Coaxial conducting polymer nanotubes: polypyrrole nanotubes coated with polyaniline or poly(<Emphasis Type="Italic">p</Emphasis>-phenylenediamine) and products of their carbonisation

Polypyrrole nanotubes were prepared by the oxidation of pyrrole with iron(III) chloride in a reaction mixture containing methyl orange. They were subsequently coated with polyaniline or poly(p-phenylenediamine) in situ during the oxidation of respective monomers in their presence. A part of the coaxial nanotubes was deprotonated using ammonia solution. The conductivity of polypyrrole nanotubes of 60 S cm^?1, was reduced after the coating, and again after the deprotonation, but maintained at a level above 10^?4 S cm^?1. Infrared and Raman spectra reflect the presence of the polymer overlayer deposited on the polypyrrole template. Thermogravimetric analysis was used as a tool for the analytical carbonisation of samples in an inert nitrogen atmosphere. The conversion of conducting polymers to nitrogen-containing carbon nanotubes was confirmed using Raman spectra.     

Structural and conformational changes during thermally‐induced crystallization of poly(trimethylene terephthalate) by infrared spectroscopy

Conformational changes occurring during thermally‐induced crystallization of poly(trimethylene terephthalate) (PTT) by annealing have been studied using density measurement, differential scanning calorimetry (DSC), and mid‐infrared spectroscopy (MIR). Infrared spectra of amorphous and semicrystalline PTT were obtained, and digital subtraction of the amorphous contribution from the semicrystalline PTT spectra provided characteristic MIR spectra of amorphous and crystalline PTT. The normalized absorbance of 1577, 1173, and 976 cm^?1 were plotted against the crystallinity showing that these bands can be used unambiguously to represent the trans conformation while the band at 1358 cm^?1 can be used to represent gauche conformation of methylene segment. The presence of a weak band at 1358 cm^?1 in the amorphous spectrum suggested that a small amount of gauche conformation is present in the amorphous phase. Infrared spectroscopy has been used for the first time as a means to estimate the trans and gauche conformations of methylene segments in PTT as a function of T_a. The amount of gauche conformation was plotted against the crystalline fraction and the extrapolation of this plot to zero crystalline fraction provided a value of 0.07, suggested that the pure amorphous phase consist of ～ 7% gauche conformation. It was found that the amorphous and crystalline gauche conformation increases at the expense of amorphous trans conformation during thermally induced crystallization of PTT. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1497–1504, 2008     

Spectroscopic investigations and structural confirmation studies on thiourea

The Fourier transform infrared and Raman spectra of thiourea have been studied in the region 4000–400 and 4000–10 cm^?1, respectively. A complete vibrational analysis on the molecular structure of thiourea has been made on the basis of C_2υ point group symmetry. The validity of the vibrational assignments on the structure of thiourea is supported by evaluating the molecular constants and the potential energy distribution.     

Vibrational analysis of tertiary alkyl bromides

Infrared spectra have been obtained for 2-bromo-2-methylpentane and 3-bromo-3-methylpentane. Both compounds exist in T_HHH and T_CHH conformations. Normal coordinate calculations were made for these two compounds and for 2-bromo-2-methylbutane, using the 44-parameter modified valence force field that was used for tertiary chlorides. Fifteen force constants were adjusted to fit 169 frequencies below 1500 cm^?1 of six molecules (two each for the three named compounds) with an average error of 5.6 cm^?1. Vibrational assignments are presented.     

A study of the electronic spectra of 9-fluorenone

The absorption and MCD spectra of 9-fluorenone are measured. The CD spectra of the β-cyclodextrin complex with 9-fluorenone are also measured. The assignment for the first (≈26.0 × 10³ cm^?1) and fourth (≈48.0 × ³ cm^?1) absorption band has been determined from the sign of the CD spectra by reference to the observed MCD spectra.     

Fourier transform Infrared characterization of melanin free ink from selected cephalopods for identification of active functional groups responsible for antioxidant activity

The present investigation aims to explore the active functional groups that are responsible for the antioxidant property in MFI from three cephalopods such as Sepia pharaonis (CMFI), Sepioteuthis lessioniana (SMFI) and Amphioctopus aegina (OMFI) using Fourier Transform Infrared (FTIR) spectroscopy. Highest DPPH scavenging activity of 28.29 ± 0.41% and metal chelating activity of 47.62 ± 0.48% were shown by MFI from A. aegina (OMFI) at a concentration of 0.045 mg/ml and 0.04 mg/ml, respectively. Though the invitro antioxidant values of MFI were low, when added with sardine fish mince, it retarded the lipid oxidation during the entire storage period and it was very clear with the lower TBARS values compared to the control. FTIR analysis of CMFI, SMFI and OMFI revealed the presence of characteristic strong band at 3361.92 cm^?1, 3364.54 cm^?1 and 3373.96 cm^?1 and at 1642.20 cm^?1, 1636.21 cm^?1and 1635.53 cm^?1,respectively. The O–H and N–H stretching vibrations and alkenyl c = c stretch corresponding to the two vibrations in all the three spectra can be accountable for its antioxidant activities leading to its wide new applications as a natural antioxidant from marine resources.     

Spectres de vibration de composes organiques des elements de la colonne IVB : V. Derives cycliques oxygenes du silicium et de l'etain: Oxa-1 sila-2 cyclopentanes,oxa-1 stanna-2 cyclopentanes et cyclopentenes

Infrared and Raman spectra of two 1-oxa-2-stannacyclopentanes, three 1-oxa-2-stannacyclopentenes and three 1-oxa-2-silacyclopentanes have been examined in the 3600—100 cm^?1 region. Assignments of the main bands observed are discussed.     

Infrared spectra recorded on dry powder spread over KBr pellets. A comparison of the spectrum of thiourea with those recorded in KBr pellets and as Nujol mulls

Infrared spectra in the 4000-250 cm⁻¹ region may be satisfactorily recorded on a dry powder spread over KBr pellets. The substance is finely and smoothly ground under Nujol and the spectrum on the Nujol mull between two KBr pellets is first recorded. Nujol is then carefully washed with light petroleum ether and a second spectrum is recorded on the fine powder adhering to the KBr pellets in the spectral regions obscured by the Nujol bands. The whole thiourea spectra recorded in KBr pellets, as Nujol mulls and as dry powder on KBr pellets are compared.     

Infrared absorption spectra of cyanide complexes of group VIII metals with nitrogen- and sulphur-containing ligands

Research into the IR absorption spectra of the products of interaction between nitrosyl pentacyanide complexes of some Group VIII metals and thiourea and thiocyanate has been carried out in the region 400–4000 cm^?1.An assumption has been made concerning the formation of intermediates of the association type. The changes in the spectra during the formation of intermediates indicate a weakening of ligand bonds with a metal-complexing agent.The data obtained for the series of cyanide complexes of Group VIII metals with heterogeneous ligands allow us to suggest a strengthening of the M-S bond between thiourea and metals in the order Os > Ni > Co ? FeThe M-NCS bond between the thiocyanate group and metals of the iron family is practically equivalent.Osmium coordinates the SCN^? group through the sulphur atom.     

Ultraviolet absorption spectra of chloramines and chlorine in carbon tetrachloride

In order to quantify mixtures of chloramines and chlorine in carbon tetrachloride, the ultraviolet spectra of monochloramine, dichloramine, trichloramine and chlorine were measured between 250 and 410 nm. Monochloramine and chlorine absorb at 259 nm (?=484.61 mol^?1 cm^?1 ) and 331 nm (?=95.7 l mol^?1 cm^?1), respectively, while dichloramine and trichloramine exhibit two peaks. For dichloramine, the maximum absorptions are observed at 255 nm (?=126.1 l mol^?1 cm^?1) and 301 nm (?=307.8 l mol^?1 cm^?1) and for trichloramine, at 262 nm (?=635.4 l mol^?1 cm^?1) and 344 nm (?=315.0 l mol^?1 cm^?1).     

Differentiation of Rhizoma Curcumas Longae and Radix Curcumae by a Multistep Infrared Macro-Fingerprint Method

A multistep infrared macro-fingerprint method was applied to identify two Chinese herbal drugs, Rhizoma Curcumas Longae (RCL) and Radix Curcumae (RC). Fourier transform infrared (FT-IR) spectra of the two were similar to each other and consistent with the 11 peaks of the spectrum of starch. RCL had a characteristic absorption peak at approximately 1514 cm^?1 that correlated to the strong peak near 1509 cm^?1 of curcumin. Between 900 cm^?1–1700 cm^?1 of the second derivative infrared (SD-IR) spectra, with higher resolution, RCL, and curcumin had 10 common peaks. In the FT-IR and SD-IR spectra of the ethanol extract, the spectra of the RCL extract and curcumin were similar, but RC was different. According to the fingerprint characteristics of the infrared spectra for RC and its extracts, the strongest peak at 1055 cm^?1; the C-O absorption peaks at 1124 cm^?1, 1106 cm^?1, and 996 cm^?1; and the strong methylene peaks at 2925 cm^?1 and 2853 cm^?1 suggest that RC contains more saccharides. In the range of 1350 cm^?1–1700 cm^?1, RCL and RC had similar two-dimensional infrared (2D-IR) correlation spectra. Both of them had three autopeaks, but the autopeaks were located at 1458 cm^?1, 1560 cm^?1, and 1641 cm^?1 for RCL and 1458 cm^?1, 1560 cm^?1, and 1669 cm^?1 for RC, suggested that the aromatic components of the two were not identical. The average correlation for the 18 RCL and 18 RC samples were 0.9906 and 0.9878, respectively, and this method achieves a good classification of the sample type.     

Infrared Cavity Ringdown Spectroscopy of Jet‐Cooled Polycyclic Aromatic Hydrocarbons

Infrared absorption spectra of the CH stretching region were observed for naphthalene, anthracene, phenanthrene, pyrene, and perylene using a heated, supersonic, slit‐jet source and cavity ringdown spectroscopy. Band positions and intensities recorded with 0.2‐cm^?1 resolution were compared with previous gas‐phase and argon matrix isolation experiments, as well as theoretical calculations. The largest matrix shift in the absorption maximum (‐7.4 cm^?1) was observed for anthracene, with all others shifted by 3.0 cm^?1 or less. Spectral features in the supersonic jet spectrum were generally narrower than those observed in the Ar matrix, with the largest matrix broadening found for the perylene (80 % increase). Low number densities observed for the larger polycyclic aromatic hydrocarbons (PAHs) suggest that the lower vapor pressure of PAHs with catacondensed four‐membered rings and with five‐membered rings other than perylene will not be detectable using our current configuration.