Hydrogenolysis of Tantalum Hydrocarbyl Complexes: Intermediates on the Road to a Dinuclear Tantalum Tetrahydride Derivative
Bibliographic record
Abstract
The synthesis, characterization, and reactivity with H 2 of a series of tantalum hydrocarbyl complexes are reported. The reaction of [NPN*]TaMe 3 ( 4, where NPN* = PhP(2-( N -mesityl)-5-Me-C 6 H 3 ) 2 ) with dihydrogen (H 2, 4 atm) results in the formation of the dinuclear tetrahydride ([NPN*]Ta) 2 (μ-H) 4 ( 5 ), without the observation of intermediates. The preparations of two alkyne benzyl complexes of the formula [NPN*]Ta(alkyne)(CH 2 Ph) (where alkyne = BTA = bis(trimethylsilyl)acetylene ( 6 ), 3-hexyne ( 7 )) are reported starting from the respective chloroalkyne complexes [NPN*]Ta(alkyne)Cl, by addition of benzylpotassium. Hydrogenation of these two alkyne benzyl complexes ultimately results in the formation of the same dinuclear tetrahydride 5; however, using lower pressures of H 2 and shorter reaction times results in the isolation of an intermediate in each case. Hydrogenation of 6 generates the alkene hydride complex [NPN*]Ta( trans -1,2-C 2 H 2 (SiMe 3 ) 2 )H ( 8 ); addition of H 2 to 7 gives [NPN*]Ta(1-hexene)H ( 9 ), in which the 3-hexyne moiety has been partially hydrogenated and isomerized to the 1-hexene regioisomer. Both of these alkene hydride complexes can be converted to the dinuclear tetrahydride complex 5 by addition of H 2 . A mechanism is proposed for the formation of the intermediates that involves hydrogenolysis of the alkyne moiety prior to the benzyl ligand; the formation of the trans -alkene units is suggested to be a result of a zwitterionic alkylidene intermediate that allows free rotation of a C–C single bond.
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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".