摘要:

AbstractThe Raman spectra of eight polycrystalline Me4N+salts have been measured and are discussed in relation to crystal structures. In most of the salts, several degenerate bands of the cation show splittings due to site symmetries lower thanTd. From the spectral shapes in the methyl deformation and stretching region and the intensity ratio of the two NC4skeletal deformation modes, the extent of cation distortion in each particular salt can be deduced. These distortions are strongest in the halides, whereas no significant crystal field effects are found in the SnCl62−and CdCl3−salts. Anion Raman bands and frequencies of lattice modes are also repor

ISSN:0377-0486    

DOI:10.1002/jrs.1250090502

出版商:John Wiley&Sons, Ltd.    

年代:1980

数据来源: WILEY

摘要:

AbstractLow frequency Raman scattering (20–400 cm−1) of aqueous solutions of uridine, cytidine, guanosine and adenosine are studied by the recently described construction of a quantityR(ν). Bands with intensity maximum at frequencies below 100 cm−1are assigned to specific protonized forms. An assignment of these bands to nucoleoside modes is preliminarily dis

ISSN:0377-0486    

DOI:10.1002/jrs.1250090503

出版商:John Wiley&Sons, Ltd.    

年代:1980

数据来源: WILEY

摘要:

AbstractRaman spectroscopy and microscopy have been used to study some catalysts: Mo supported on alumina. Different Mo species were found, depending upon the amount of molybdenum deposited on the carrier. At low coverages (4% wt MoO3) distorted molybdate tetrahedra were observed. Increasing the surface coverage resulted in the formation of a polymolybdate phase with octahedrally surrounded molybdenum. Additionally, ‘bulk MoO3’ appeared when amounts were above 16% wt MoO3. When the supports were washed during their preparation with aqueous NH4OH and HNO3solutions, preferential formation of polymolybdate phase was observed. In case of washing with alkaline solution ‘free MoO3’ was also detected. Finally using the Raman microprobe MOLE, a map giving the distribution of the different species at the surface of support was o

ISSN:0377-0486    

DOI:10.1002/jrs.1250090504

出版商:John Wiley&Sons, Ltd.    

年代:1980

数据来源: WILEY

摘要:

AbstractThe Raman spectra of the low temperature phase single crystal of KHSO4and of polycrystalline KDSO4have been investigated at 300 and 90 K. Infrared spectra of polycrystalline samples have been recorded for compaison in the 4000 to 30 cm−1range. An assignment of bands due to internal vibrations to their symmetry species (Raman) and in terms of approximate type of motion is given. a distinction between the bands corresponding to cyclic dimers and infinite chains is possible in the case of the OH group and most skeletal stretching vibrations. An interpretation of lattice bands using an oriented gas model is proposed. Hydrogen bonding in the KHSO4crystal is discusse

ISSN:0377-0486    

DOI:10.1002/jrs.1250090505

出版商:John Wiley&Sons, Ltd.    

年代:1980

数据来源: WILEY

摘要:

AbstractThe Raman spectra of bovine pancreatic α‐chymotrypsin and trypsin were determined from 7% aqueous solutions and lyophilized solids containing residual sulfate ion. A large amount of β‐pleated‐sheet structure is present in both molecules, as shown by the contour of the amide III region, but trypsin contains substantially more α‐helical conformation than does chymotrypsin. There is evidence of some change in structure of both molecules in solution as compared with the solids. The tyrosines are all or nearly all weakly hydrogen bonded in both enzymes, and the binding of sulfate ion is also weak in the lyophili

ISSN:0377-0486    

DOI:10.1002/jrs.1250090506

出版商:John Wiley&Sons, Ltd.    

年代:1980

数据来源: WILEY

摘要:

AbstractRaman and IR spectra of the crystalline solids Hg2(H2PO4)2, Hg3(PO4)2and Hg2SeO4are reported and assigned in terms of vibrational modes of the unit cell. Frequenciesv(HgO) andv(HgHg) are located in the ranges 210–280 and 180–190 cm−1, respectively. Inter‐ and intramolecular coupling of HgO modes, and of some ligand vibrations, result in splittings of from 5 to 40 cm−1, which can be related to the crystal and molec

ISSN:0377-0486    

DOI:10.1002/jrs.1250090507

出版商:John Wiley&Sons, Ltd.    

年代:1980

数据来源: WILEY

摘要:

AbstractResonance Raman spectra are reported for Ni(II), Cu(II), Pd(II) and Pt(II) tetraphenylporphine (TPP). Systematic examination of the resonance Raman frequencies of these and of previously reported TPP derivatives has revealed three bands which exhibit a linear correlation with porphyrin core size (Ct–N), near 1460 cm−1(polarized), 1540 cm−1(anomalously polarized) and 1570 cm−1(polarized). Parameters derived from the correlations indicate a reasonable similarity between these TPP modes and those of biological‐type metalloporphyrins which also correlate

ISSN:0377-0486    

DOI:10.1002/jrs.1250090508

出版商:John Wiley&Sons, Ltd.    

年代:1980

数据来源: WILEY

摘要:

AbstractThe IR and Raman spectra (4000–50 cm−1) of (chloromethyl)cyclopropane and epichlorohydrin have been recorded in all three physical states. It has been concluded from the spectroscopic data and from variable temperature studies that (chloromethyl)cyclopropane exists as an equilibrium mixture ofgauche(95%) andcis(5%) conformers in the liquid state, while only thegaucheform persists in the solid phase. The enthalpy difference between these two rotamers was found to be 1.40±0.10 kcal mol−1. Similarly, epichlorohydrin has also been shown to exist as an equilibrium mixture ofgauche‐1 (70%),gauche‐2 (21%) andcis(9%) conformers in the liquid state, with only thegauche‐1 form remaining in the solid phase. Enthalpy differences among these conformers were determined to be 1.2±0.2 kcal mol−1(gauche‐1 vs.cis) and 0.70±0.10 kcal mol−1(gauche‐1 vsgauche‐2). Apparently steric repulsions between the chlorine atom and β ring‐hydrogens destabilize thecisconformation in each molecule. For each molecule, a vibrational assign

ISSN:0377-0486    

DOI:10.1002/jrs.1250090509

出版商:John Wiley&Sons, Ltd.    

年代:1980

数据来源: WILEY

摘要:

AbstractSolid state infrared and Raman spectra of thymine, thymine monohydrate, three types of chloro(thyminato‐N1)ethylenediamineplatinum(II) complexes and three types of potassium thyminate (trihydrate, monohydrate, anhydrous compound) are reported and compared. The effects of hydrogen bonding, intermolecular coupling, crystal symmetry and tautomerism are discussed. For the anhydrous potassium thyminate a tautomeric structure, different from that found in the tri‐ and monohydrate, is postula

ISSN:0377-0486    

DOI:10.1002/jrs.1250090510

出版商:John Wiley&Sons, Ltd.    

年代:1980

数据来源: WILEY

摘要:

AbstractFor cyclopropyl isothiocyanate, the infrared (4000–200 cm−1) spectra in all three phases and the Raman spectra of the liquid and solid phases have been recorded. From Raman depolarization data and infrared gas phase band contours it has been concluded that cyclopropyl isothiocyanate exists in thecisconformation. No evidence for the existence of other conformations was found in the spectra. An assignment for 24 of the 27 fundamental vibrational modes has been proposed and this assignment has been shown to be in excellent agreement with vibrational assignments for other monosubstituted cyclopropanes and a number of isothiocyanate compou

ISSN:0377-0486    

DOI:10.1002/jrs.1250090511

出版商:John Wiley&Sons, Ltd.    

年代:1980

数据来源: WILEY