Rapid Intermolecular C-H Activation of Aromatic Substrates at a Cationic, Electrophilic Molybdenum (VI) Nitrido Complex: Mechanistic Nuance in C-H Amination
Bibliographic record
Abstract
When the cationic, octahedral terminal nitrido complex of Mo(VI) supported by a diborate pentadentate ligand is generated in the absence of trapping nucleophiles, it rapidly activates the C(sp2)-H bonds of simple arenes to form the cationic imido complexes [[ArMo(V)]=NR]+ (R = H; PhX, X = H, o,m,p-F). Detailed Density Functional Theory computational work and extensive experimental studies support a mechanism with homolytic aromatic substitution character, wherein electrophilic attack of the arene system initiates N-C bond formation, but use of electrons from the Mo≡N triple bond completes the bond formation through an open-shell singlet transition state that formally reduces the metal center to Mo(V) and imbues the arene ring with significant radical character. This transition state is enthalpically 15 kcal mol-1 lower in energy than the classical “Wheland-type” transition state common to electrophilic aromatic substitution paths proposed in related systems. Subsequent intramolecular transfer of the arene hydrogen to the imido nitrogen atom leads to the cationic Mo(IV) anilido complex [[ArMoIV]-NHPh]+, which rapidily reacts with available [[ArMoVI]≡N]+ by a proton-coupled electron transfer step to generate the observed 1 : 1 mixture of imido products [[ArMo(V)]=NR]+ (R = H; PhX, X = H, o,m,p-F). This second phase of the mechanism is also supported computationally and by an experimental crossover experiment and is driven by significant coordination-induced bond weakening (CIBW) in the N-H bond of the [[ArMoIV]-NHPh]+ and the lack of CIBW in the imido N-H product. The novel mechanism of C-H addition to the electrophilic terminal nitrido opens new low energy pathways for the development of systems capable of catalytic nitrogen atom transfer to C-H bonds.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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) | 0.000 | 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 teacher head, 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".