The Infra-Red and Raman Spectra of Cyclopentane, Cyclopentane-<i>d</i>1, and Cyclopentane-<i>d</i>10

Miller, Foil A.; Inskeep, Richard G.

doi:10.1063/1.1747535

Cited by 95 publications

(17 citation statements)

References 26 publications

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“…Raman and infrared arguments are used to discuss the probable configurations' of Sa ("crown" structure, D4d), S2Ch ("gauche" structure, C2), and P4 (tetrahedral, T d ) (98). The spectra of deuterated cyclopentane (99) lead to the conclusion that the mole cule is not planar, but cannot distinguish between several possibilities, in cluding the model with pseudorotation proposed by Kilpatrick, Pitzer & Spitzer (100). It is generally accepted that the low energy rotational isomer of 1,2-dibromoethane has the trans C2h configuration; evidence now has been presented which suggests the high energy form possesses the "skew" C2 form (101).…”

Section: Structuresmentioning

confidence: 94%

Experimental Molecular Structure

Roth¹

1951

Annu. Rev. Phys. Chem.

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The principal sources of information about the structure of molecules in the free state are electron diffraction of gases, spectroscopy in the infrared, Raman and microwave regions, and x-ray diffraction of crystals. The past year has seen a continuation of the trends noted in the previous review by Beach (1). The general structural principles for most small molecules are reasonably well understood, and interest now is directed toward the under standing of variations of bond distances and angles in different molecules and the study of more complicated systems, such as larger molecules and the nature of intramolecular motions.The advances in experimental technique in electron and x-ray diffraction and the striking interpretations of pure rotational spectra in the microwave region are beginning to provide a body of information relating to interatomic parameters where the distances are reliable to 0.01 'A or better and the angles reliable to 30'. Some success is obtained in accounting for the observed inter atomic distances by modifying the sum of the covalent radii (14) with cor rections for ionic or multiple bond character (18), but it is apparent that there is a need for precise data from a largernumberof molecules. Accordingly, much of the work at the present time is concerned with improving experi mental techniques or with redetermining the structures of many molecules by the newer methods.Electron diffraction.-The need for the determination of a larger number of parameters has led many workers in the field of electron diffraction to search for increased sensitivity and objectivity. The early electron diffraction investigations were accomplished by the visual correlation technique, where calculated intensity patterns based on assumed models were compared with the visually observed diffraction pattern. As the complexity of the molecules studied increased and it became necessary to determine a larger number of parameters, it became increasingly difficult to arrive at a unique model. At the present time, many molecules are being reinvestigated and extensive work is being done to increase the accuracy and sensitivity of the experimen tal techniques.Recent papers by . the Karles (2, 3, 4) and Hastings & Bauer (5, 8) con tain detailed discussions of the effects of various experimental factors on the diffraction patterns: the proper design of a gas nozzle for introducing the sample into the electron beam, the effect of finite sampJe size and divergence of the beam, mUltiple scattering, the use of beam stops and rotating sectors, and the response characteristics of photographic emulsions.1 This review is a continuation of that of Beach (1) and covers approximately the year 19 50.

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Section: Structuresmentioning

confidence: 94%

Experimental Molecular Structure

Roth¹

1951

Annu. Rev. Phys. Chem.

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“…However, the concept of pseudorotation was not instantly accepted by the chemical community. Alternative analyses of spectroscopic data claimed that there was no need to invoke it to explain the existing data . Nevertheless, various groups worked on the development of mathematical procedures defining ring puckering and pseudorotation, as for example Hendrickson, or Pickett and Strauss .…”

Section: Description Of Puckered Ring Systemsmentioning

confidence: 99%

Dieter Cremer's contribution to the field of theoretical chemistry

Kraka

Cremer²

2019

Int J of Quantum Chemistry

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This legacy article reviews the contributions of Dieter Cremer (1944‐2017) to the field of theoretical chemistry, highlighting his major accomplishments in method development and applied quantum chemistry, which has led to many advances in the field. His work reflects an extraordinary breadth and deep understanding of theory, which is needed to solve complex chemical problems. His passion for science has inspired many colleagues in the past and will do so in the future.

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“…For example, the single out-of-plane vibration of cyclobutane is a low frequency, double minimum motion which contributes 3.8 cal/mole-°K to the room temperature entropy (13). Also, one of the two outof-plane vibrations of cyclopentane has been described as a pseudorotation (or alternate puckering of CH2 groups) and contributes an exceptional 5.8 cal/mole-°K to that structure (2, 7). Further, although normal mode frequencies of alkane rings larger than cyclohexane have not been reported (their entropies having been determined by third law methods), Dreiding models strongly suggest extensive freedom of motion in their structures.…”

Section: Rationalementioning

confidence: 99%