Modelling extended systems containing siloxane building blocks

Bakk, István; Bóna, Áron; Nyulászi, László; Szieberth, Dénes

doi:10.1016/j.theochem.2006.05.028

Cited by 8 publications

(11 citation statements)

References 37 publications

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“…We focus on the CCSD(T)/cc-pVTZ full geometry optimization. This level has been emphasized as the lowest [24] 149.3 1.637 0.43 B3P86/6-311ϩG(3df) [26] 149.4 1.633 0.27 B-LYP/6-311G(3df) [26] 149.2 1.654 0.33 B-P86/6-311ϩG(3df) [26] 144.5 1.653 0.49 B3LYP/6-311ϩG** [27] 180.0 1.643 0.00 M05-2X/aug-cc-pV(Tϩd)Z [28] computational level for which a compromise between the desired accuracy and computational feasibility has been reached [6], yet no such calculations have been reported.…”

Section: Previous Theoretical Calculationsmentioning

confidence: 99%

Structure and properties of disiloxane: An ab initio and post‐Hartree–Fock study

Derzi

Gregušová

Runge

et al. 2008

Int J of Quantum Chemistry

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As a prototype of the SiOOOSi bonding region for silica modeling, especially the highly flexible SiOOOSi angle deformation, we studied the structure of disiloxane (H 3 SiOOOSiH 3 ), with ab initio calculations on the SCF, MBPT (2), CCSD, and CCSD(T) levels of theory. The convergence of the results is studied for a series of basis sets of increasing quality. Large basis sets including f functions are necessary to obtain reliable results for the structure and the barrier to linearization of the molecule. The following structure and energy parameters are the results of CCSD(T)-fc/cc-pVTZ calculations: SiOO distance is 1.645Å, the SiOOOSi angle 145.3°, and the barrier to linearization 0.48 kcal/mol.

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Section: Previous Theoretical Calculationsmentioning

confidence: 99%

Structure and properties of disiloxane: An ab initio and post‐Hartree–Fock study

Derzi

Gregušová

Runge

et al. 2008

Int J of Quantum Chemistry

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“…The chemistry of siloxanes has received considerable attention during the last decades from both experimental − and theoretical − viewpoints owing to their widespread applicability in material science, , catalysis, − and so forth. Siloxanes display peculiar structures consisting of wide Si–O–Si angles (∼150°), far larger than the tetrahedral C–O–C angle in analogue ethers, whereas Si–O bond distances (1.62–1.64 Å) are significantly shorter than the lengths obtained by summing their covalent radii (1.77 Å).…”

Section: Introductionmentioning

confidence: 99%

“…Siloxanes display peculiar structures consisting of wide Si–O–Si angles (∼150°), far larger than the tetrahedral C–O–C angle in analogue ethers, whereas Si–O bond distances (1.62–1.64 Å) are significantly shorter than the lengths obtained by summing their covalent radii (1.77 Å). Back-bonding p(O) → d(Si) interactions, , initially set as the cause for these anomalous features, were superseded by hyperconjugative effects, ,,− as ab initio studies revealed negligible contribution of the d-orbitals in the bonding of hypervalent p-block elements, − despite contrasting opinions . Still, the significance of d-orbitals in anionic species such as R 3 SiO (−) and R 2 SiO (2−) was highlighted, , while studies , based on electron localization function calculations suggested an essentially ionic description of the Si–O bond.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Insights into the Structural Differences between Organic and Inorganic Amines/Ethers

2020

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The contrasting geometrical features between organic and inorganic counterparts of amines and oxanes are explained in terms of an offset between attractive (donor–acceptor) and repulsive (donor–donor) interactions. Natural bond orbital (NBO) calculations carried out at the density functional theory level of theory reveal that hyperconjugative effects in the organic amines and ethers are overcome by repulsive interactions occurring between the lone pair on the nitrogen/oxygen atom and the adjacent σ(C–R) bond orbitals. Although displaying lower energies than in the corresponding organic derivatives, the LP(X) → σ*(E–R) (X = N, O; E = Si, Ge, Sn) interactions in heavier counterparts overcome the LP(X)···σ(E–R) repulsions, impacting thus their structural behavior. In addition, NBO deletion optimizations emphasize that among hyperconjugations, back-bonding effects of the LP(X) → d(E) type dictate to a lesser extent the anomalous structures of the inorganic amines and oxanes.

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“…The concept of vicinal hyperconjugative interactions is well documented for sylil groups and siloxanic derivatives, − but much less is known about their heavier analogues. The development of computational chemistry enabled a better awareness of these issues, − but the most important contribution regarding the clarification of the hyperconjugative phenomena within disiloxanic derivatives belongs to Weinhold and West, , whose work led to new perspectives in the field …”

Section: Introductionmentioning

confidence: 99%

Bridging a Knowledge Gap from Siloxanes to Germoxanes and Stannoxanes. A Theoretical Natural Bond Orbital Study

2017

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Explaining the nature of the E-O chemical bond (E = Si, Ge, Sn) has been a great challenge for theoretical chemists during the last decades. Among the large number of models used for this purpose, the one based on hyperconjugative interactions sheds more light on the nature of chemical bonding in siloxanes. Starting from this concept, this study aimed to evaluate the impact of siloxane type hyperconjugative effects on the structural features of germoxanic and stannoxanic species and in addition to assess if p-d-like back-bonding interactions can also play important roles in determining the particular structures of these heavier analogues of ethers. Natural bond orbital deletion (NBO DEL) optimizations, carried out at the DFT level of theory, revealed that hyperconjugative effects dictate to a large extent the structural behavior of these species. Furthermore, this study points out that p-d back-bonding interactions also influence the equilibrium geometry of these species, although acting as a secondary electronic effect within the E-O-E moieties (E = Si, Ge, Sn).

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Modelling extended systems containing siloxane building blocks

Cited by 8 publications

References 37 publications

Structure and properties of disiloxane: An ab initio and post‐Hartree–Fock study

Structure and properties of disiloxane: An ab initio and post‐Hartree–Fock study

Theoretical Insights into the Structural Differences between Organic and Inorganic Amines/Ethers

Bridging a Knowledge Gap from Siloxanes to Germoxanes and Stannoxanes. A Theoretical Natural Bond Orbital Study

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