Ambient Temperature Carbene-Mediated Depolymerization: Stoichiometric and Catalytic Reactions of <i>N</i>-Heterocyclic- and Cyclic(Alkyl)Amino Carbenes with Poly(<i>N</i>-Methylaminoborane) [MeNH–BH<sub>2</sub>]<sub><i>n</i></sub>
Bibliographic record
Abstract
The reactions of the N -heterocyclic carbenes (NHCs) IDipp and I t Bu and the cyclic(alkyl)amino carbene (CAAC) CAAC Me with polyaminoborane [MeNH–BH 2 ] n were investigated. Stoichiometric quantities of each carbene were found to cause rapid and complete depolymerization, with the major B–N-containing product identified as the NHC-aminoborane adduct, IDipp–BH 2 NMeH ( 1 ), cyclic borazane [MeNH–BH 2 ] 3, or borazine [MeNBH] 3 with IDipp, I t Bu, and CAAC Me, respectively. With substoichiometric quantities of IDipp and I t Bu (down to 10 and 2.5 mol %, respectively), complete loss of high molar mass material was also detected, indicating that the depolymerization is catalytic. The main products of the reaction with substoichiometric IDipp were IDipp–BH 2 NMeH ( 1 ) and [MeNH–BH 2 ] 3 and with substoichiometric I t Bu, [MeNH–BH 2 ] 3, and [MeNBH] 3 with product ratios dependent on the quantity of NHC used. Under analogous conditions with CAAC Me, high molar mass material persisted alongside the formation of [MeNBH] 3 . Further reactivity studies with cyclic borazane [MeNH–BH 2 ] 3 and MeNH 2 ·BH 3 provided insights into depolymerization pathways. IDipp showed no reactivity toward [MeNH–BH 2 ] 3, whereas with 3 equiv of I t Bu and CAAC Me, the dehydrogenation product [MeNBH] 3, was formed. With MeNH 2 ·BH 3, 2 equiv of carbene were used as the first acts to accept dihydrogen; the major products with IDipp, I t Bu, and CAAC Me were IDipp–BH 2 NMeH ( 1 ), [MeNBH] 3, and (CAAC Me H)HB═NMeH ( 2 ), respectively. The double E–H (E = B, N) bond activation product (CAAC Me H)HB═NMe(HCAAC Me ) ( 3 ) was isolated from the reaction between 3 equiv of CAAC Me and MeNH 2 ·BH 3 . A unified mechanism for donor-mediated depolymerization of [MeHN–BH 2 ] n is proposed.
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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) | 0.001 | 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".