On the in-plane vibration frequencies of the vinylidene, d1-, and d2-vinylidene halides. I. Force fields and normal modes. II. Characteristic group vibrations

1969 ◽  
Vol 47 (6) ◽  
pp. 935-948 ◽  
Author(s):  
J. M. Freeman ◽  
T. Henshall
Keyword(s):  
Force Fields ◽  
Normal Modes ◽  
Vibrational Analysis ◽  
Approximation Methods ◽  
Vibration Frequencies ◽  
Normal Coordinate ◽  
Valence Force Field ◽  
Plane Group ◽  
Characteristic Group ◽  
Available Information

An investigation has been undertaken of the characteristic in-plane group vibrations of the vinylidene and d2-vinylidene groups from the viewpoints both of approximation methods of the vibrational analysis of, and aids to assignments in, molecules containing such groups.The need in these studies for reliable force fields for the vinylidene halides has caused us to undertake a normal coordinate analysis of the in-plane vibrations of these molecules using a modified valence force field, and including all the available information from the hydrogen and deuterium isotopically substituted species.

Vibrational Spectra and Normal Coordinate Calculations of Chlorophosphazene Compounds. III. Polydichlorophosphazene

1982 ◽  
Vol 36 (3) ◽  
pp. 277-281 ◽  
Author(s):  
M. M. Coleman ◽  
J. Zarian ◽  
P. C. Painter
Keyword(s):  
Force Field ◽  
Vibrational Spectra ◽  
Reasonable Agreement ◽  
Normal Modes ◽  
Normal Coordinate ◽  
Valence Force ◽  
Valence Force Field

Vibrational spectra and normal coordinate calculations of polydichlorophosphazene (PDP) are presented. The valence force field derived previously from the two conformers of octachlorocyclotetraphosphazene was directly transferred to a distorted “cis-plan” helical model of PDP without refinement. A reasonable agreement between the observed and calculated frequencies was obtained and the assignment of the normal modes of PDP is discussed.

Frequencies and Normal Modes of Benz(a)anthracene. A MINDO/3-FORCES Treatment

2001 ◽  
Vol 56 (6-7) ◽  
pp. 493-498
Author(s):  
Rehab M. Kubba ◽  
Muthana Shanshal
Keyword(s):  
Normal Modes ◽  
Normal Coordinate Analysis ◽  
Quantum Mechanical ◽  
Ir Absorption ◽  
Quantum Mechanical Calculations ◽  
Vibration Frequencies ◽  
Normal Coordinate ◽  
First Time

Abstract Quantum mechanical calculations, based on the MINDO/3-FORCES method, of the vibration fre­quencies and IR absorption intensities of benz(a)anthracene are reported and compared with calculated vibration frequencies of that molecule. For the first time a complete normal coordinate analysis for the molecule is reported. Interesting correlations between vibration motions of the same type but different symmetries are reported.

Vibrational analysis and force field for some secondary iodides

1977 ◽  
Vol 55 (2) ◽  
pp. 310-317 ◽  
Author(s):  
G. Crowder ◽  
Zahra Najafi
Keyword(s):  
Force Field ◽  
Infrared Spectra ◽  
Vibrational Analysis ◽  
Zero Order ◽  
Average Error ◽  
Average Difference ◽  
Normal Coordinate ◽  
Valence Force ◽  
Valence Force Field ◽  
Wave Numbers

Normal coordinate calculations were made for 2-iodopropane and the three conformers of 2-iodobutane. A forty-seven parameter modified valence force field was used that fit eighty-four frequencies of those four molecules in the 250–1500 cm−1 region with an average error of 4.8 cm−1, or 0.6%. Infrared spectra were obtained for 2-iodopentane and 3-iodopentane, and zero-order normal coordinate calculations were made for three conformers of 2-iodopentane and for five conformers of 3-iodopentane. The SHH, SHH′, and SCH conformers of 2-iodopentane are present, along with one or two unidentified ones, and 3-iodopentane exists as a mixture of the SHH, SHH′, SCH, and SCH′ conformers. The force constants that were determined for the four conformers of 2-iodopropane and 2-iodobutane were transferred to the two secondary iodo-pentanes with good success. The average difference between observed and calculated wave-numbers for 164 frequencies of seven conformations of these two compounds was 5.8 cm−1.

Vibrational Spectra and Normal Coordinate Calculations of Chlorophosphazene Compounds. II. Octachlorocyclotetraphosphazene

1982 ◽  
Vol 36 (3) ◽  
pp. 272-277 ◽  
Author(s):  
J. Zarian ◽  
P. C. Painter ◽  
M. M. Coleman
Keyword(s):  
Force Field ◽  
Vibrational Spectra ◽  
Normal Modes ◽  
Normal Coordinate ◽  
Valence Force ◽  
Valence Force Field ◽  
Good Agreement

Vibrational spectra and normal coordinate calculations of octachlorocyclotetraphosphazene (OCTP) are presented. A common valence force field for the two conformers (T and K forms) of OCTP has been developed. A good agreement between the observed and calculated frequencies of OCTP was obtained and the assignments of the normal modes are discussed.

Force Field and Mean Amplitudes of Vibration of (NH2)2CX Compounds ( X = O, S, Se)

1982 ◽  
Vol 37 (11) ◽  
pp. 1289-1291
Author(s):  
Marcelo Campos ◽  
Guillermo Díaz
Keyword(s):  
Force Field ◽  
Matrix Method ◽  
Force Fields ◽  
Normal Coordinate Analysis ◽  
Vibrational Assignment ◽  
Normal Coordinate ◽  
Mean Amplitudes Of Vibration ◽  
Valence Force ◽  
Valence Force Field

Normal coordinate analysis of urea, thiourea and selenourea was performed on the basis of the general valence force field; Wilson’s FG matrix method has been used. The final force fields were obtained through an iterative selfconsistent method. The vibrational assignment for these molecules is discussed. Calculated mean amplitudes of vibration for the urea series and their deuterated derivatives are reported.

Vibrational analysis of alkyl bromides. II. Secondary bromides

1977 ◽  
Vol 55 (19) ◽  
pp. 3413-3419 ◽  
Author(s):  
G. A. Crowder ◽  
Maurice Iwunze
Keyword(s):  
Force Field ◽  
Raman Spectra ◽  
Vibrational Analysis ◽  
Average Error ◽  
Infrared And Raman Spectra ◽  
Normal Coordinate ◽  
Valence Force ◽  
Vibrational Assignments ◽  
Valence Force Field ◽  
Alkyl Bromides

Infrared and Raman spectra were obtained for 2-bromopentane, 3-bromopentane, 2-bromohexane, and 3-bromohexane. Vibrational assignments were made for several conformers of each compound with the aid of normal coordinate calculations. A 48 parameter modified valence force field was obtained that fit 221 frequencies of three conformers of 2-bromopentane, 4 conformers of 3-bromopentane, and 1 conformer of 2-bromobutane with an average error of 4.1 cm−1. This force field was transferred to the bromohexanes, with good results.

Vibrational Spectra and Normal Coordinate Calculations of Chlorophosphazene Compounds. I. Hexachlorocyclotriphosphazene

1982 ◽  
Vol 36 (3) ◽  
pp. 265-271 ◽  
Author(s):  
P. C. Painter ◽  
J. Zarian ◽  
M. M. Coleman
Keyword(s):  
Force Field ◽  
Vibrational Spectra ◽  
Normal Modes ◽  
Normal Coordinate ◽  
Valence Force ◽  
Valence Force Field

Vibrational spectra and normal coordinate calculations of hexachlorocyclotriphosphazene (HCTP) are presented. Attempts to obtain a common valence force field for HCTP and the two conformers of octachlorocyclotetraphosphazene which were not successful, are discussed. The force field obtained for HCTP is, by necessity, relatively simple. Nevertheless, we have been able to make assignments of the normal modes and resolve some apparent discrepancies in the literature.

Infrared spectrum, potential constants, and structure of thio-thionyl fluoride

1965 ◽  
Vol 18 (5) ◽  
pp. 627 ◽  
Author(s):  
RD Brown ◽  
GP Pez ◽  
MF O'Dwyer
Keyword(s):  
Electronic Structure ◽  
Infrared Spectrum ◽  
Thermodynamic Functions ◽  
Vibrational Analysis ◽  
Force Constants ◽  
Normal Coordinate ◽  
Infrared Data

An investigation of the infrared spectrum of gaseous thio-thionyl fluoride (SSF2) results in the following assignment of fundamentals: A': v1 760.5�0.2cm-1, v2 718.5�0.2 cm-1, v3 411.2�0.4cm-1, v4 364.1�0.3 cm-1. A": v5 692.3�0.8cm-1, v6 337.6�0.4 cm-1. A normal coordinate vibrational analysis has been performed and a set of ten force constants evaluated. Some conclusions are given regarding the electronic structure of SSF2. Thermodynamic functions based on the usual assumptions have been calculated for SSF2. A set of potential constants has been evaluated for disulphur monoxide, SSO, using the available infrared data.

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