Molecular mechanics parameters for organosilicon compounds calculated from <i>ab initio</i> computations

Grigoras, S.; Lane, Thomas H.

doi:10.1002/jcc.540090105

Cited by 62 publications

(25 citation statements)

References 22 publications

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“…The average bond angle at the oxygen varies between 130 0 and 180 °C. This wide bond angle, as well as the balance of the electrostatic and dispersion interactions, provide another important difference between organosiloxanes and other organic compounds: the chain conformation of siloxanes consists of sequential bonds in alternating cis-trans conformation [2], while the most stable conformation of hydrocarbons, for example, is trans-trans. Such molecular differences are expected to have an impact on the physical and chemical properties of the corresponding substances.…”

Section: Physico-chemical Properties May Be Broadly Classified Into Tmentioning

confidence: 99%

Eco-Relevant Properties of Selected Organosilicon Materials

Mazzoni¹,

Roy²,

Grigoras³

1997

The Handbook of Environmental Chemistry

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Section: Physico-chemical Properties May Be Broadly Classified Into Tmentioning

confidence: 99%

Eco-Relevant Properties of Selected Organosilicon Materials

Mazzoni¹,

Roy²,

Grigoras³

1997

The Handbook of Environmental Chemistry

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“…8,47 It has since been correctly pointed out that in disiloxane the barrier to conversion from conformation I to II is lower by rotation of the H 3 Si-groups, than inversion of the Si-O-Si angle. 7 However, considering the very low experimental and theoretical barriers, we would expect significant populations of linear or near-linear conformations at room temperature.…”

Section: Energetic Barrier To Linearizationmentioning

confidence: 99%

An evaluation of correlation-consistent basis sets in calculating the structure and energetics of (H3Si)2O, H3SiOH, and H3SiO−

Nicholas¹,

Feyereisen²

1995

The Journal of Chemical Physics

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Ab initio studies on the interstellar molecules C3H2 and C3H and the mechanism for the neutral-neutral reaction C(3 P)+C2H2We studied the structure of disiloxane ͑H 3 Si-O-SiH 3 ͒, silanol ͑H 3 Si-OH͒, and the silanol anion ͑H 3 Si-O Ϫ ͒ with ab initio molecular orbital theory and the correlation consistent polarized basis sets of Dunning and co-workers. We present results for the correlation consistent polarized valence double zeta ͑cc-pVDZ͒, triple zeta ͑cc-pVTZ͒, and quadruple zeta ͓cc-pVQZ͑-g͔͒ basis sets. Optimized geometries and energies are given at both the restricted Hartree-Fock ͑RHF͒ level and with the inclusion of electron correlation by second order Mo "ller-Plesset perturbation theory ͑MP2͒. The correlation consistent basis sets provide a systematic expansion of the orbital basis set, with each set of additional functions adding a similar contribution to the correlation energy. We find that the calculated molecular properties show exponential convergence with increasing basis set size. These calculations answer long-standing questions regarding the structure and barrier to linearization of disiloxane. Results at the highest level of theory ͓MP2/cc-pVQZ͑-g͔͒ for disiloxane gave a Si-O-Si bond angle of 147.0°, a Si-O bond length of 1.641 Å, and a barrier to linearization of 0.4 kcal/mol. All of these values are in excellent agreement with experimental results. Similar calculations for silanol gave a Si-O bond length of 1.655 Å, an O-H bond of 0.955 Å, and a Si-O-H angle of 117.9°. The MP2/cc-pVQZ͑-g͒ deprotonation energy ͑⌬E 0 ͒ for silanol, calculated as the energy difference between silanol and its anion, is Ϫ366.6 kcal/mol. The effects of electron correlation at the MP4 level are studied in all three molecules using the cc-pVDZ and cc-pVTZ basis sets.

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“…There are two possible C, conformations of disiloxane, the doubly staggered (I) and the doubly eclipsed (11), shown in Figure 1. On the basis of electron diffraction data, Almenningen et al' concluded that disiloxane has the C2, symmetry of conformation I. Disiloxane crystals exhibit a distorted C, structure similar to 1.…”

Section: Experimental Lhltamentioning

confidence: 99%

An ab initio investigation of disiloxane using extended basis sets and electron correlation

Nicholas¹,

Winans²,

Harrison³

et al. 1992

J. Phys. Chem.

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The ab initio structure of disiloxane (H3Si-0-SiH3) is studied with a series of basis sets of increasing quality, including extended basis sets and explicit electron correlation at the singlereference single and doubleexcitation codiguration interaction (SDCI) level. The calculated molecular geometry and barrier to linearization of the Si-0-Si bond angle are compared to experimental and previous theoretical values. Results show that the rigorous expansion of the basii set leads to a good agreement with experimental data at the restricted Hartree-Fock (RHF) level. The potential energy curves and force constants for variation of the Si-0-Si angle and the Si-H and Si-0 bond lengths are calculated and discussed in relationship to molecular modeling of zeolites and clays. We also investigate coupling between the Si-0 bond and Si-0-Si bond angle. We discuss the effects of temperature on the comparison between theoretical and experimental results.

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Molecular mechanics parameters for organosilicon compounds calculated from ab initio computations

Cited by 62 publications

References 22 publications

Eco-Relevant Properties of Selected Organosilicon Materials

Eco-Relevant Properties of Selected Organosilicon Materials

An evaluation of correlation-consistent basis sets in calculating the structure and energetics of (H3Si)2O, H3SiOH, and H3SiO−

An ab initio investigation of disiloxane using extended basis sets and electron correlation

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