Synthesis and Characterization of Palladium Complexes Supported by an NPN-Phosphido Ancillary Ligand
Bibliographic record
Abstract
The Pd II coordination chemistry of the phosphido ligand [(2-Me 2 NC 6 H 4 ) 2 P] − (NPN) is reported, along with the results of studies documenting the utility of such complexes as catalyst precursors for the Heck arylation of olefins. Examples of κ 1 -, κ 2 -, and κ 3 -NPN coordination to Pd are described. The secondary phosphine (NPN)H ( 1 ) was reacted with 0.5 equiv of [(C 3 H 5 )PdCl] 2 to afford the dimeric species [(κ 2 - NP N)PdCl] 2 ( 2 ) in 96% yield. Similarly, the reaction of 1 with 0.33 equiv of [Pd(OAc) 2 ] 3 led to the formation of dimeric [(κ 2 - NP N)PdOAc] 2 ( 3 ) in 98% yield. Complexes 2 and 3 were both crystallographically characterized to reveal dipalladium species that feature bridging phosphido groups, as well as terminal chloride and acetate ligands, respectively. Treatment of 3 with Me 3 SiOTf resulted in the formation of the analogous triflate complex [(κ 2 - NP N)PdOTf] 2 ( 4; 78% yield). Treatment of 2 with (C 3 H 5 )MgCl afforded the thermally sensitive, phosphido-bridged complex [(κ 1 -N P N)Pd(η 3 -C 3 H 5 )] 2 ( 5 ) in 87% yield. The solid-state structure of 5 was confirmed by X-ray crystallography. Precoordination of BPh 3 to the NPN phosphido group was attempted in order to discourage the formation of phosphido-bridged (NPN)Pd species. Thus, the reaction of 1 with 1 equiv each of KCH 2 Ph and BPh 3 led to the formation of [N(P·BPh 3 )N]K ( 6 ), which was isolated in 88% yield. The related complex [N(P·BH 3 )N]H ( 7 ) was prepared by treatment of 1 with BH 3 ·THF, and crystallographic characterization confirmed the preferential coordination of the NPN ligand phosphorus to BH 3 . The reaction of 6 with 0.5 equiv of [Pd(C 3 H 5 )Cl] 2 led to the formation of [κ 3 - N ( P ·BPh 3 ) N ]Pd(η 1 -C 3 H 5 ), which was isolated in 45% yield. Complexes 2 – 4 were established as precatalysts for the Heck coupling of ethyl acrylate and haloarenes.
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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 | 0.001 |
| 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 | 0.001 | 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".