Addition of Primary and Secondary Phosphines to Dinuclear Tantalum Hydrides: Synthesis of Phosphides and Phosphinidenes via P−H Bond Activation
Bibliographic record
Abstract
The dinuclear complex ( RPh [NPN]Ta) 2 (μ-H) 4 (where RPh [NPN] = [RP(CH 2 SiMe 2 NPh) 2 ] and R = Ph, Cy) shows remarkable reactivity with molecular nitrogen, producing the side-on end-on bound dinitrogen complex ( RPh [NPN]Ta) 2 (μ-η 1:η 2 -N 2 )(μ-H) 2 . This tantalum tetrahydride also promotes other small molecule activation. Addition of secondary phosphines HPR‘ 2 (R‘ = Ph, Cy) to ( RPh [NPN]Ta) 2 (μ-H) 4 accesses trihydride phosphide systems ( RPh [NPN]Ta) 2 (μ-H) 3 (μ-PR‘ 2 ). Addition of primary phosphines H 2 PR‘ ‘ (R‘ ‘ = Cy, Ad) gives bridging phosphinidene tantalum complexes ( RPh [NPN]Ta) 2 (μ-H) 2 (μ-PR‘ ‘). Molecular structures as determined by X-ray crystallography for the complexes ( PhPh [NPN]Ta) 2 (μ-H) 3 (μ-PCy 2 ) and ( CyPh [NPN]Ta) 2 (μ-H) 2 (μ-PAd) are presented. Isotopic labeling studies offer mechanistic insights into the reactivity of this tetrahydride system. Reaction of Cy 2 PH with ( CyPh [NPN]Ta) 2 (μ-D) 4, for instance, gives solely the monohydride dideuteride complex ( CyPh [NPN]Ta) 2 (μ-H)(μ-D) 2 (μ-PCy 2 ). This labeling study indicates that D 2 loss forms the reactive species, ( CyPh [NPN]Ta) 2 (μ-D) 2, which promotes small molecule activation. Addition of CyPH 2 to ( CyPh [NPN]Ta) 2 (μ-D) 4 gives a series of isotopomers, with an average composition of 0.67 H and 1.33 D, supporting a 1,2-H 2 elimination step to form the tantalum phosphinidenes. These results are tied into the general reactivity of ( RPh [NPN]Ta) 2 (μ-H) 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) | 0.002 | 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".