Toward an experimental bond order

Jules, Joseph L.; Lombardi, John R.

doi:10.1016/j.theochem.2003.09.008

Cited by 27 publications

(26 citation statements)

References 80 publications

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“…The causes for these large deviations have not been clarified, 1 but in the literature, the thermochemical or spectroscopic properties of compounds containing fluorine often present differentiated behavior. 45,46 As expected, the optimization of the HLC parameters achieved smaller deviations with respect to experimental data, particularly for standard enthalpies of formation. The histograms of the deviations obtained for the G3(MP2)//B3-CEP and G3(MP2)//B3 enthalpies of formation are shown in Fig.…”

Section: A First-and Second-row Elementssupporting

confidence: 74%

Assessment of G3(MP2)//B3 theory including a pseudopotential for molecules containing first-, second-, and third-row representative elements

Rocha

Pereira

Morgon

et al. 2013

The Journal of Chemical Physics

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G3(MP2)∕∕B3 theory was modified to incorporate compact effective potential (CEP) pseudopotentials, providing a theoretical alternative referred to as G3(MP2)∕∕B3-CEP for calculations involving first-, second-, and third-row representative elements. The G3∕05 test set was used as a standard to evaluate the accuracy of the calculated properties. G3(MP2)∕∕B3-CEP theory was applied to the study of 247 standard enthalpies of formation, 104 ionization energies, 63 electron affinities, 10 proton affinities, and 22 atomization energies, comprising 446 experimental energies. The mean absolute deviations compared with the experimental data for all thermochemical results presented an accuracy of 1.4 kcal mol(-1) for G3(MP2)∕∕B3 and 1.6 kcal mol(-1) for G3(MP2)∕∕B3-CEP. Approximately 75% and 70% of the calculated properties are found with accuracy between ±2 kcal mol(-1) for G3(MP2)∕∕B3 and G3(MP2)∕∕B3-CEP, respectively. Considering a confidence interval of 95%, the results may oscillate between ±4.2 kcal mol(-1) and ±4.6 kcal mol(-1), respectively. The overall statistical behavior indicates that the calculations using pseudopotential present similar behavior with the all-electron theory. Of equal importance to the accuracy is the CPU time, which was reduced by between 10% and 40%.

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Section: A First-and Second-row Elementssupporting

confidence: 74%

Assessment of G3(MP2)//B3 theory including a pseudopotential for molecules containing first-, second-, and third-row representative elements

Rocha

Pereira

Morgon

et al. 2013

The Journal of Chemical Physics

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“…Proposals to generalize Eq. (8) by including more than two elements in the same fitting have recently appeared in the literature [38,39].…”

Section: 71mentioning

confidence: 99%

“…It is a threedimensional vector with components and magnitude defined in Eqs (38) and (39), respectively:…”

Section: Atomic Dipolar Polarization [M(w)]mentioning

confidence: 99%

An Introduction to the Quantum Theory of Atoms in Molecules

Matta

Boyd

2007

The Quantum Theory of Atoms in Molecules

483

599

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“…Besides accuracy, an important aspect of a theory's “serviceability”20 is the connection with chemists' way of thinking. The locality of one‐electron orbitals, purposefully preserved in the VB theories, facilitates interpretation of the results in chemical terms such as bond length ,21–24 bond order ,25–37 and bond stretching force constant 38–45. Most of these properties reflect “local bond strength,”39, 46 which is commonly associated with a bond in a chemical species, a single point on a potential energy surface, PES.…”

Section: Relevant Chemical Notions and Modelsmentioning

confidence: 99%

Electronic reorganization: Origin of sigma trans promotion effect

2006

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Binding of two ligands trans to each other by some transition metal complexes may be cooperative [Khoroshun et al., Mol Phys 2002, 100, 523]. Several interesting consequent effects include (i) inverse relationship between bond strength and binding affinity; (ii) smaller coordination barriers to formation of weaker bonds; (iii) enhancement of Lewis acidity with increased number of ligands. We describe a simple model, trans promotion effect (TPE), which considers electronic reorganization between two Lewis structures, and predicts the above-mentioned effects. The applied result of present study is the unified perspective on several facts of heme chemistry. Particularly, we reiterate an important but often overlooked notion, developed previously within the spin pairing model [Drago and Corden, Acc Chem Res 1980, 13, 353], that, in hemoproteins, the proximal histidine and the distal ligand such as O 2 or CO cooperate in promoting electronic reorganization. As a result, depopulation of d z 2 orbital upon ligand binding contributes to the phenomenon of hemoglobin cooperativity. The presented density functional (B3LYP) calculations on realistic models, the processes of carbon monoxide binding by Fe(II) porphyrins and dinitrogen binding by triamido/triamidoamine Mo(III) complexes, particularly the evaluation of the coordination barriers due to spin-state change by location of the minima on seams of crossing, support the TPE model predictions. From a broader theoretical perspective, the present study would hopefully stimulate the development of much needed frameworks and tools for facile comparisons of wave functions and their properties between different geometries, species, and electronic states. Advancement of practical wave function comparisons may yield fresh qualitative perspectives on chemical reactivity, and promote better understanding of related concepts such as electronic reorganization.

show abstract

Toward an experimental bond order

Cited by 27 publications

References 80 publications

Assessment of G3(MP2)//B3 theory including a pseudopotential for molecules containing first-, second-, and third-row representative elements

Assessment of G3(MP2)//B3 theory including a pseudopotential for molecules containing first-, second-, and third-row representative elements

An Introduction to the Quantum Theory of Atoms in Molecules

Electronic reorganization: Origin of sigma trans promotion effect

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