On The Lower Lewis Basicity of Siloxanes Compared to Ethers
Bibliographic record
Abstract
Abstract 1,3‐Dimethyldisiloxane, O(SiH2Me)2, diethyl ether, OEt2, and their metal complexes (Li+,Ag+) have been used as model systems to uncover the reasons underlying the lower Lewis basicity of siloxanes compared to analogous ethers. Bonding in the metal complexes has been analyzed with quantum theory of atoms in molecules as well as natural bond orbital theory. The binding to Li+ by O(SiH2Me)2 and OEt2 is largely of monopole – dipole type whereas binding of Ag+ also shows small charge transfer components. The more ionic Si–O bonds in O(SiH2Me)2 compared to C–O bonds in OEt2 lead to more negative charge on the oxygen atom of O(SiH2Me)2 but the electrostatic attraction between metal cations and OEt2 is calculated to be slightly stronger by interacting quantum atoms energy decomposition analysis. The lower electrostatic attraction by O(SiH2Me)2 is due to repulsion between positively charged silicon atoms and the metal cations that compensate for the stronger attraction from the oxygen atom relative to OEt2. The total interaction of metal cations with O(SiH2Me)2 was calculated to be almost as strong as that with OEt2 and the lower stability of O(SiH2Me)2 complexes and the lower Lewis basicity of O(SiH2Me)2 is attributed to changes in the bonding and polarization of the ligands in the presence of metal cations. The polarization of O–Si bonds in O(SiH2Me)2 raises the energy of the molecule more than does the polarization O–C bonds in OEt2. Despite the lower stability of O(SiH2Me)2 metal complexes, solid state reaction enthalpies arising from a volume‐based thermodynamics approach suggest that they could be stabilized with a sufficiently large anion such as [Al(ORF)4]–.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".