Adjacent DIM isoelectronic molecules and chemical similarity among triatomics

Cavanaugh, Rick; Marsa, R. L.; Robertson, J.H.; Hefferlin, Ray

doi:10.1016/0022-2860(96)09255-1

Cited by 9 publications

(7 citation statements)

References 12 publications

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“…Subsequently, triatomic molecules with s and p atoms were subjected to multiple-regression smoothing and forecasts, using powers of the three axes described in the previous section, just to see what general trends might emerge. The following properties were treated: H a ; IP; log p K 1000 ; and logQ(1000) [48]. When the fitted data are compared with the tabulated data (when such exist) the agreements are surprisingly good for f(R) < 19, e.g., an average difference of 21 kJ mol - Fig.…”

Section: Least-squares and Multiple-regression Resultsmentioning

confidence: 99%

“…(11). Just as the next step for diatomics was printing main-group molecular configurations and terms, or data, on 8 x 8 chessboards, so the next step (after item 5.3.e) for triatomics entailed plotting H a [47]; IP; S o 298.15 [48]; S o (internal) 1000 ; Q(1000) and the bond angle in 8 x 8x 8 cubes, as shown by one example in Fig. (12).…”

Section: Distributions Of Data In Fixed-period Volumesmentioning

confidence: 99%

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Kronecker-Product Periodic Systems of Small Gas-Phase Molecules and the Search for Order in Atomic Ensembles of Any Phase

Hefferlin¹

2008

CCHTS

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The periodic law, manifested in the chart of the elements, is so fundamental in chemistry and related areas of physics that the question arises "Might periodicity among molecules also be embodied in a periodic system?" This review paper details how a particular periodic system of gas-phase diatomic molecules, allowing for the forecasting of thousands of new data, was developed. It can include ionized and even quarked-nuclei molecules and it coincides with locality (averaging) and the additivity found in some data; it has interesting vector properties, and it may be related in challenging ways to partial order. The review then explains how periodic systems for triatomic and four-atomic species are evolving along a similar path. The systems rest largely upon exhaustive comparisons of tabulated data, relate to some extent to the octet rule, and include reducible representations of the dynamic group SO(4) in higher spaces. Finally, the paper shows how periodicity can be quantified in data for larger molecules. Data for properties of homologous or substituted molecules, in any phase, are quantified with a vector index, and the index for one set can be transformed into that for another set.

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Section: Least-squares and Multiple-regression Resultsmentioning

confidence: 99%

Section: Distributions Of Data In Fixed-period Volumesmentioning

confidence: 99%

Kronecker-Product Periodic Systems of Small Gas-Phase Molecules and the Search for Order in Atomic Ensembles of Any Phase

Hefferlin¹

2008

CCHTS

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“…Other atlases of globally predicted data for vibration frequencies and ionization potentials of diatomic molecules are in preparation. These efforts have already yielded an interesting phenomenon of possible theoretical interest: certain series of triatomic molecules have, for at least one property and for certain regions of chemical data space, chemical similarity at least as pronounced as do isoelectronic series in many regions of the space. , …”

Section: Discussionmentioning

confidence: 99%

“…The colleagues (Dr. H. Kuhlman and undergraduate students at SAU) who participated in various aspects of this work are too numerous to mention here. Their names are given on pages 185, 186, and 293 of ref and in the bylines and acknowledgments of refs , , , and 15. The reviewers and publisher contributed invaluable comments.…”

Section: Acknowledgmentsmentioning

confidence: 99%

An Atlas of Forecasted Molecular Data. 1. Internuclear Separations of Main-Group and Transition-Metal Neutral Gas-Phase Diatomic Molecules in the Ground State

Hefferlin

Davis

Ileto

2003

J. Chem. Inf. Comput. Sci.

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Needed spectroscopic data on diatomic molecules can often be found in the superb critical tables of Huber and Herzberg or in the literature published since 1979. Unfortunately, these sources apply to only a fraction of the diatomic species that can exist and so investigators have had to rely on interpolation, additivity, or ad hoc rules to estimate needed values, all of which require other information that is often lacking. This Atlas presents 1001 additional internuclear separations for use until critical tables are available to fill the needs more precisely. The Atlas was produced by mining the data from Huber and Herzberg for trends with least-squares analysis and with neural network software. There are 162 molecules about whose data Huber and Herzberg had no qualifications and whose data were employed for this work; 248 copies of data with low and high magnitudes were added to reduce the effects of frequency. Internuclear separations for 1001 species not found in Huber and Herzberg are presented, and least-squares predictions supplement some of them. The results, i.e., the Atlas, are presented as Table A, Supporting Information. The average error, based on the average of the absolute differences between the predicted values and tabulated values for the molecules having Huber and Herzberg data, is 0.074 A; if each error is expressed as a percent of the forecast to which it pertains, the average of these errors is 2.94%. There are 25 "questionable" data from Huber and Herzberg, not used in the preparation of the Atlas, for which predictions are included in the Atlas. Of these, 14 agree with the predicted internuclear separations to within twice the stated errors. Additional atlases for other properties of diatomic molecules are in preparation.

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“…4 Internal entropies at an arbitrarily chosen 1000 K [indicated by S 1000 (internal)] also came from those tables and the use of a conversion formula. 1 When results for both entropies are described, the generic symbol S is used. The use of difference sources (in this case, different editions of JANAF) reflects the fact that the work was done in several stages.…”

Section: Data and Associated Errorsmentioning

confidence: 99%

Molecular Similarity for Small Species: Refining the Isoelectronic Index

Hefferlin

Matus

2001

J. Chem. Inf. Comput. Sci.

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This paper tests a chemical-similarity model against properties of gas-phase neutral triatomic and four-atom molecules. The model is a variant of the Diatomics-in-Molecules (DIM) picture, which considers a molecule to be the superposition of all diatomic molecules that could be formed from adjacent atoms in the molecule. The variant is that adjacent atoms are counted as a diatomic molecule only if they are bonded. The tests consist of investigating whether molecules with the same number of electrons, computed by the adjacent-DIM model, have data more similar than do molecules selected at random. The tests vindicate the model for the heat of atomization and for the equilibrium constant for formation, they agree with the model with lesser confidence for the entropy and the partition function, and they show that the model fails for the ionization potential. The model applies with most confidence to molecules with the more electronegative atoms from rows 2 or 3 (those of greatest interest in organic chemistry) and with lesser confidence otherwise. For these properties and these molecules, the model passes graphical and statistical tests at least as well as does the traditional isoelectronic model. Thus, this work refines what may be called the isoelectronic index.

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Adjacent DIM isoelectronic molecules and chemical similarity among triatomics

Cited by 9 publications

References 12 publications

Kronecker-Product Periodic Systems of Small Gas-Phase Molecules and the Search for Order in Atomic Ensembles of Any Phase

Kronecker-Product Periodic Systems of Small Gas-Phase Molecules and the Search for Order in Atomic Ensembles of Any Phase

An Atlas of Forecasted Molecular Data. 1. Internuclear Separations of Main-Group and Transition-Metal Neutral Gas-Phase Diatomic Molecules in the Ground State

Molecular Similarity for Small Species: Refining the Isoelectronic Index

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