A QTAIM and Electron Delocalization Computational Study of<i>tert</i>-Butylmethylene, Trimethylsilylmethylene, and Trimethylgermylmethylene. A New Method for Unambiguously Characterizing the Bonding between Pairs of Atoms in Reaction Intermediates
Bibliographic record
Abstract
While studies on the experimental photolytic and thermolytic extrusion of nitrogen from tert-butyldiazomethane and tert-butyldiazirine and the decomposition of other precursors have shown a mixture of C-H and C-C insertion products depending on conditions, the analogous trimethylsilyldiazomethane undergoes solely Si-C insertion. Description of the singlet tert-butylmethylene intermediates potentially involved in the C-H and C-C insertion reactions and were addressed through computational means by Armstrong et al. (J. Am. Chem. Soc. 1995, 117, 3685-3689). In addition to re-examining singlet tert-butylmethylene at a higher level of theory [CCSD/6-311+G(d,p)], we have studied the silicon and germanium analogues trimethylsilylmethylene and trimethylgermylmethylene. A computational atoms-in-molecules and atomic-basin-delocalization-indices analysis established that the singlet carbenes, while exhibiting varying degrees of delocalization, are not bridged species based on the fact that none possess a pentacoordinate methyl group. In addition, from the results, we are able to make a prediction of solely a Ge-C insertion product for the extrusion of nitrogen from trimethylgermyldiazomethane. Most importantly, we demonstrated that a combination of quantum theory of atoms in molecules (QTAIM) molecular graphs, the evaluation of delocalization indices, and a visualization of the closeness of atomic basins [Formula: see text] a QTAIM-DI-VISAB analysis [Formula: see text] should be considered as the method of choice for unambiguously characterizing the bonding between pairs of atoms not only of carbenes but of other reaction intermediates such as carbocations, carbanions, and radicals.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".