Thermochemistry of hexafluoro-anions of M IV (M = Si, Ti, Mn, or Re) and lattice energy calculations for their salts

Blandamer, Michael J.; Burgess, John; Hamshere, Stephen J.; Peacock, R. D.; Rogers, J.; Jenkins, H. Donald Brooke

doi:10.1039/dt9810000726

Cited by 14 publications

(6 citation statements)

References 3 publications

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“… a Calculated distances include scalar relativistic corrections for second- and third-row metal complexes. b Observed values are averages over N (obs) from Table III of ref a. …”

Section: Resultsmentioning

confidence: 99%

“…The net charge on many Werner complexes leads to large environmental effects in solution and the solid state, and it is difficult to make direct thermochemical measurements on the isolated complexes themselves. However, there is a combined experimental/computational approach, originally developed by Jenkins and Pratt, which uses thermochemical considerations and total lattice potential energy calculations 8 to derive heterolytic bond energies E (M−X) .…”

Section: Introductionmentioning

confidence: 99%

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A Density Functional and Thermochemical Study of M−X Bond Lengths and Energies in [MX₆]^2- Complexes: LDA versus Becke88/Perdew86 Gradient-Corrected Functionals

Deeth

Jenkins

1997

J. Phys. Chem. A

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Local density approximation (LDA) and Becke88/Perdew86 gradient-corrected density functional theory calculations are used to estimate the heterolytic bond energy, E(M−X), corresponding to the process [MX6]g 2- → Mg 4+ + 6Xg -. The computed data, including scalar relativistic corrections for second- and third-row metals, are benchmarked against updated values for the bonds Zr−Cl, Mo−Cl, Pd−Cl, Sn−Cl, Hf−Cl, W−Cl, W−Br, Re−Cl, Re−Br, Os−Cl, Ir−Cl, Pt−Cl, Pt−Br, Ti−Cl, Ti−Br, and Ni−F derived from a combination of thermochemical and computational data on the antifluorite A2MX6 hexahalometallate(IV) salts. The LDA tends to overbind, and the bond energies are generally too large. The BP method systematically reduces these values by about 60 kJ mol-1, giving a significantly better comparison with experiment. However, LDA-optimized M−X bond lengths, both in vacuo and for a model ‘in crystal' {K8[PdCl6]}6+ cluster, are generally in better agreement with experiment.

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“… a Calculated distances include scalar relativistic corrections for second- and third-row metal complexes. b Observed values are averages over N (obs) from Table III of ref a. …”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Density Functional and Thermochemical Study of M−X Bond Lengths and Energies in [MX₆]^2- Complexes: LDA versus Becke88/Perdew86 Gradient-Corrected Functionals

Deeth

Jenkins

1997

J. Phys. Chem. A

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“…the enthalpy of the reaction SiF4 + 2F~-* 1• SiF62', has been reported as -33 kcal/mol from one experimental approach40 and ranging between -1 and -33 kcal/mol depending on the way the data was interpreted according to another study. 41 We computed the enthalpy of the analogous reaction involving carbon, CF4 + 2F-1 CF62", to be +127 kcal/mol. A comprehensive theoretical study of the fluoride affinities of a number of species, on the basis of SCF calculations, has been reported by O'Keeffe.…”

Section: Discussionmentioning

confidence: 99%

Ab initio studies of molecular structures and energetics. 4. Hexacoordinated NF6- and CF62- anions

Ewig¹,

Wazer²

1990

J. Am. Chem. Soc.

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“…One of the reactions for unimolecular processes is the conformational change of the tricyclic hydrophobic moiety of imipramine (three ring core). This may be excluded because the structure is rigid and it has not special substituent, which could undergo a conformational change except the branch bonded to 12N in Figure .…”

Section: Resultsmentioning

confidence: 99%

“…Δ G is related to the standard enthalpy change, Δ H , and the standard entropy change, Δ S , as Δ G = Δ H – T Δ S . The entropy change for the rotational motion of isomers is well approximated to be constant or very small meaning that the contribution of the entropy change to the free energy change is not dominant. Therefore, it can be assumed that the free energy change is approximated by the change of enthalpy, Δ H .…”

Section: Resultsmentioning

confidence: 99%

Ultrasonic Relaxation Measurements in Aqueous Solution and Molecular Orbital Calculation on Imipramine

Nishikawa

2013

J. Phys. Chem. B

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Ultrasonic absorption coefficients have been measured in aqueous solution of imipramine {3-(10,11-dihydro-5H-dibenzo[b,f]azepin-5-yl)-N,N-dimethylpropan-1-amine} in the frequency range of 0.8-220 MHz at 25 °C. The frequency dependences of the observed absorption was characterized by a Debye-type relaxational equation with two relaxation frequencies, although only one relaxation had been observed in aqueous solutions of the related molecule amitriptyline. Both of the relaxation frequencies in imipramine solutions were found to be independent of the solute concentration and the amplitudes of the relaxational absorptions increase linearly with increasing solute concentration. It was therefore concluded that these two relaxations are associated with unimolecular reactions, such as a structural change due to rotational motions of the bond in the specified group in the imipramine molecule. To analyze quantitatively the source of the relaxations, semiempirical molecular orbital methods have been applied to determine the standard enthalpy of formation of the imipramine molecule at various dihedral angles around the bonds in the alkylamine side chain. According to the results, only one rotational motion of carbon-carbon bond in the side chain was found to be appropriate and the three minima of the standard enthalpy of formation was obtained as a function of the rotational angle. At the three minimum positions, the values of the standard enthalpy of formation are almost the same. With the assumptions (a) that rotational motion is not accompanied by a volume change of the reaction and (b) that the standard free energy change is close to the difference in the values between the standard enthalpies of formation, the equilibrium constants for the rotational isomerization have been calculated to be near unity. Hence, the forward and backward rate constants of the isomerization reactions are nearly the same. If one assumes that there are two kinds of rotational motions in one bond of the molecule, one proceeds with a rate constant on the order of 10(8) s(-1), whereas the other with a rate constant on the order of 10(6) s(-1). The faster and slower processes are also distinguished by the height of the standard enthalpy of formation.

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Thermochemistry of hexafluoro-anions of M IV (M = Si, Ti, Mn, or Re) and lattice energy calculations for their salts

Cited by 14 publications

References 3 publications

A Density Functional and Thermochemical Study of M−X Bond Lengths and Energies in [MX₆]^2- Complexes: LDA versus Becke88/Perdew86 Gradient-Corrected Functionals

A Density Functional and Thermochemical Study of M−X Bond Lengths and Energies in [MX₆]^2- Complexes: LDA versus Becke88/Perdew86 Gradient-Corrected Functionals

Ab initio studies of molecular structures and energetics. 4. Hexacoordinated NF6- and CF62- anions

Ultrasonic Relaxation Measurements in Aqueous Solution and Molecular Orbital Calculation on Imipramine

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Thermochemistry of hexafluoro-anions of M IV (M = Si, Ti, Mn, or Re) and lattice energy calculations for their salts

Cited by 14 publications

References 3 publications

A Density Functional and Thermochemical Study of M−X Bond Lengths and Energies in [MX6]2- Complexes: LDA versus Becke88/Perdew86 Gradient-Corrected Functionals

A Density Functional and Thermochemical Study of M−X Bond Lengths and Energies in [MX6]2- Complexes: LDA versus Becke88/Perdew86 Gradient-Corrected Functionals

Ab initio studies of molecular structures and energetics. 4. Hexacoordinated NF6- and CF62- anions

Ultrasonic Relaxation Measurements in Aqueous Solution and Molecular Orbital Calculation on Imipramine

Contact Info

Product

Resources

About

A Density Functional and Thermochemical Study of M−X Bond Lengths and Energies in [MX₆]^2- Complexes: LDA versus Becke88/Perdew86 Gradient-Corrected Functionals

A Density Functional and Thermochemical Study of M−X Bond Lengths and Energies in [MX₆]^2- Complexes: LDA versus Becke88/Perdew86 Gradient-Corrected Functionals