Group vibrations and the vibrational analysis of molecules containing methylene groups. Part I. The basic equations and the application of the method to methylene dichloride and cyclopropane

1968 ◽  
Vol 46 (12) ◽  
pp. 2129-2134 ◽  
Author(s):  
J. M. Freeman ◽  
T. Henshall
Keyword(s):  
Vibrational Analysis ◽  
Ring System ◽  
Form Part ◽  
Methylene Groups ◽  
Basic Equations ◽  
Bending Modes ◽  
Deformation Modes ◽  
Methylene Group ◽  
Molecular Framework ◽  
Secular Determinant

The vibrations of the methylene group first considered by King have been reexamined; and the group factorization procedure previously applied to molecules containing methyl groups has now been extended to molecules containing methylene groups. The vibrational analysis of such molecules can be simplified by factoring from the secular determinant those frequencies that are characteristic of the symmetric and antisymmetric CH2 stretching, and the [Formula: see text] angle bending modes. Corrections are then applied to the G and F matrices to account for the interactions with the molecular framework of the CH2 'rocking', and [Formula: see text] angle deformation modes, where the atoms X may form part of a ring system.

Group vibrations and the vibrational analysis of molecules containing methylene groups. Part II. Ethylene oxide, d4-ethylene oxide, and ethylene sulfide

1968 ◽  
Vol 46 (12) ◽  
pp. 2135-2139 ◽  
Author(s):  
J. M. Freeman ◽  
T. Henshall
Keyword(s):  
Ethylene Oxide ◽  
Vibrational Analysis ◽  
Vibrational Assignments ◽  
Group Frequency ◽  
Methylene Groups

Vibrational analyses, based on the group frequency factorization procedure of King and Crawford, are reported for ethylene oxide, d4-ethylene oxide, and ethylene sulfide in an attempt to decide between two possible vibrational assignments for these molecules.The results, whilst not providing an unequivocal decision between the assignments, nevertheless do suggest that the higher frequencies in the A2 and B2 species may be preferentially assigned to the methylene rocking modes.

Assesment of Vibrational Coupling at Solid-SAM Junctions

2011 ◽  
Author(s):  
Christopher B. Saltonstall ◽  
John C. Duda ◽  
Patrick E. Hopkins ◽  
Pamela M. Norris
Keyword(s):  
Thermal Conductance ◽  
Chemical Properties ◽  
Self Assembled Monolayers ◽  
Vibrational Coupling ◽  
Thermal Boundary Conductance ◽  
Hartree Fock ◽  
Assembled Monolayers ◽  
Methylene Groups ◽  
Methylene Group ◽  
And Chemical Properties

Self-assembled monolayers (SAMs) have recently garnered much interest due to their unique electrical and chemical properties. The limited literature detailing SAM thermal properties has suggested that thermal boundary conductance (TBC) at solid-SAM junctions is not only low, but also insensitive to changes in SAM length as the number of methylene groups (-CH2-) along alkanedithiol chains is varied from 8 to 10. The present study investigates the vibrational spectra of alkanedithiol SAMs as a function of the number of methylene groups forming the molecule backbone via Hartree-Fock methods and the subsequent effects on TBC calculated using a diffuse scattering model. In particular, the vibrational overlap between the alkanedithiol and Au is studied. It is found that despite the addition of 9 new vibrational modes per added methylene group, only one of those modes is elastically accessible to Au. It is believed that this “vibrational inaccessibility” is the cause of the insensitivity of thermal conductance to molecule length.

scholarly journals Raman spectroscopy of the minerals boléite，cumengéite， diaboléte and phosgenite — implications for the analysis of cosmetics of antiquity

2003 ◽  
Vol 67 (1) ◽  
pp. 103-111 ◽  
Author(s):  
R. L. Frost ◽  
P. A. Williams ◽  
W. Martens
Keyword(s):  
Molecular Structure ◽  
Raman Spectroscopy ◽  
Molecular Structures ◽  
Carbonate Mineral ◽  
Mineral Formation ◽  
Secondary Mineral ◽  
Secondary Mineral Formation ◽  
Bending Modes ◽  
Wavenumber Region ◽  
Deformation Modes

AbstractThe application of Raman spectroscopy to the study of the mixed cationic Pb-Cu and Pb-Cu-Ag minerals: boleite, cumengeite and diaboleite has enabled their molecular structures to be compared. Each of these three minerals shows different hydroxyl-stretching vibrational patterns, but some similarity exists in the Raman spectra of the hydroxyl-deformation modes. The low-wavenumber region is characterized by the bands assigned to the cation-chloride stretching and bending modes. Phosgenite is also a mixed chloride-carbonate mineral and a comparison is made with the molecular structure of the aforementioned minerals. Raman spectroscopy lends itself to the study of these types of minerals in complex mineral systems of secondary mineral formation.

Mechanistic studies of the reactions of 2-methylpropene with deuterium over supported metal catalysts

1989 ◽  
Vol 424 (1866) ◽  
pp. 39-56 ◽  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Metal Catalysts ◽  
Supported Metal Catalysts ◽  
Mechanistic Studies ◽  
Dissociative Mechanism ◽  
Methyl Group ◽  
Methylene Groups ◽  
Methylene Group ◽  
Supported Metal

Deuterium NMR spectroscopy, gas chromatography and mass spectrometry have been used to examine the products from the reaction of 2-methylpropene with deuterium over supported metal catalysts. The detailed information, so obtained, about the number, location and grouping of deuterium atoms in both the exchanged alkenes and the 2-methylpropanes formed by addition provided evidence about possible mechanisms. With palladium, exchange was faster than addition and the deuterium atoms were randomly distributed in the alkene, probably through a π-allyl dissociative mechanism. With platinum and rhodium, exchange occurred preferentially in the methylene groups of the alkene and the results indicated a dissociative mechanism involving adsorbed vinyl intermediates together with some intramolecular double-bond movement through a π-allyl type of species. Relatively little exchange occurred with iridium. The activities of the metals for production of alkane at 235 K were Rh > Ir > Pd > Pt but the spread was only a factor of about 20. With all metals except palladium further exchange occurred during the addition process, but this was mainly concentrated in one methyl group. This behaviour was explained in terms of mechanisms that permitted additional exchange of the methylene group of the alkene to take place during the addition process.

An abinitio study of the A2A′—X2A″ vibronic transition in the free radical HNF

1983 ◽  
Vol 61 (11) ◽  
pp. 2500-2505 ◽  
Author(s):  
Miljenko Perić ◽  
Sigrid D. Peyerimhoff ◽  
Robert J. Buenker
Keyword(s):  
Free Radical ◽  
Potential Energy ◽  
Small Molecules ◽  
Large Angle ◽  
Vibrational Analysis ◽  
Electronic States ◽  
Measured Data ◽  
Vibronic Transition ◽  
Bending Modes ◽  
Linear Geometry

Potential energy curves for the two lowest electronic states X2A″ and A2A′(2Π in linear geometry) of HNF are calculated employing configuration interaction. A vibrational analysis of the A2A′—X2A″ transition is undertaken; stretching and bending modes are treated separately but vibronic coupling and large-angle bending is taken into consideration explicitly. The various vibronic levels including their K-type structure are compared with measured data wherever available and the results indicate that the prediction of vibronic spectra in small molecules on the basis of purely abinitio data is now within reach.

scholarly journals Group vibrations and the vibrational analysis of molecules containing the CD3 group

1968 ◽  
Vol 46 (12) ◽  
pp. 2175-2178 ◽  
Author(s):  
J. M. Freeman ◽  
T. Henshall
Keyword(s):  
Dimethyl Sulfide ◽  
Vibrational Analysis ◽  
Characteristic Group ◽  
Dimethyl Selenide ◽  
Vibrational Problem ◽  
Secular Determinant

The procedure introduced by King and Crawford for the simplification of the molecular vibrational problem by factorization from the secular determinant of characteristic group frequencies, and applied by them to the CD3 group, has been reexamined and programmed in English-Electric KDF-9 Algol. A few small corrections have been made to their results, and equations are given for the calculation of CD3 group frequencies in molecules bearing such groups.The group factorization procedure has also been applied to the calculation of the skeletal frequencies of ααα-d3-dimethyl sulfide and d6-dimethyl selenide.

Methylsteroids. VII. Factors Affecting the Hydrolysis of 7α- and 11β-Acetoxylanostanes

1961 ◽  
Vol 14 (1) ◽  
pp. 48
Author(s):  
CS Barnes ◽  
BD Beilby
Keyword(s):  
Carbonyl Group ◽  
Carbonyl Groups ◽  
Factors Affecting ◽  
Steric Crowding ◽  
Methylene Groups ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Methylene Group

Doubly bonded methylene groups have been introduced into 7α- and 11β-acetoxylanostanes and the rate of hydrolysis compared with compounds having a hydroxy or carbonyl group at the same position as the methylene group. It was found that methylene groups facilitate hydrolysis of the hindered acetoxy groups in the same way, but not to the same extent, as carbonyl groups. It is concluded that the facilitation in each case results from a conformational disturbance, but that there is some other factor involved in carbonyl facilitation. It was not possible to demonstrate a similar effect resulting from steric crowding of substituents.

PERIODATE–PERMANGANATE OXIDATIONS: II. DETERMINATION OF TERMINAL METHYLENE GROUPS

1955 ◽  
Vol 33 (11) ◽  
pp. 1710-1713 ◽  
Author(s):  
R. U. Lemieux ◽  
E. Von Rudloff
Keyword(s):  
Quantitative Yield ◽  
Permanganate Oxidation ◽  
Initial Stage ◽  
Methylene Groups ◽  
Methylene Group

The periodate–permanganate oxidation of a terminal methylene group can be made to produce formaldehyde in high although not quantitative yield. Since the yields compare favorably with those obtained by ozonolysis, the reagent can serve as the basis for a convenient micromethod for the estimation of terminal methylene groups. The less than theoretical yields of formaldehyde are believed mainly due to the conversion of the olefin in part to α-hydroxyaldehyde in the initial stage of the reaction.

Diethyl 7,12-dihydro-8-iodo-6,13-dioxo-cis-7H,11H-2,4-dioxa-5a,6a,12a,13a-tetraazabenz[f]cycloocta[cd]azulene-13b,13c-dicarboxylate

2006 ◽  
Vol 62 (7) ◽  
pp. o2738-o2740
Author(s):  
Yun-Feng Chen ◽  
Yu-Zhou Wang ◽  
Hui-Zhen Guo ◽  
Yi-Tao Li
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Membered Ring ◽  
The Other ◽  
Π Interactions ◽  
Compound C ◽  
Methylene Groups ◽  
Methylene Group

The title compound, C21H23IN4O8, is a glycoluril derivative with five fused rings. An iodobenzene ring is fused to a seven-membered ring which binds two of the N atoms from separate rings of the glycoluril system. The other N atoms are linked via methylene groups to form an eight-membered ring with two ether O atoms separated by an additional methylene group. The crystal structure is stabilized by inversion-related C—H...π interactions together with C—H...O non-classical hydrogen bonds.

13C Nuclear Magnetic Resonance Studies. 47. 13C Spectra of some exo-Methylenecycloalkanes and -norbornanes

1975 ◽  
Vol 53 (4) ◽  
pp. 589-595 ◽  
Author(s):  
S. H. Grover ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Carbonyl Group ◽  
Ring System ◽  
Magnetic Resonance Studies ◽  
13C Nuclear Magnetic Resonance ◽  
Methylene Group ◽  
Shielding Effects ◽  
Nuclear Magnetic

The shielding effects of the exo-methylene group on neighboring carbons in several cycloalkanes, methylcyclohexanes, and in the norbornane ring system have been characterized by 13C n. m. r. examination of 28 compounds. The results are compared with those for the carbonyl group and the utility of these data for structural elucidations is discussed. The more distinctive trends exhibited by the methyl carbons in these systems are compared with those for cyclohexanes, cyclohexanones, norbornanes, and norcamphors.

Sign in / Sign up

Export Citation Format

Share Document